ibus -iBUS Evaluation Report Rapid Manufacturing of ...h2020ibus.eu/.../09/D4-1-iBUS...customised-designs-Rev-2.0-Final.pdf · In a co-design system, the solution space, ... the elicitation

iBUS “an integrated business model for customer driven custom product supply chains”

Grant Agreement: 646167

Deliverable 4.1

Evaluation Report Rapid Manufacturing of

customised designs

"This publication has been produced with the assistance of the European Union. The contents of this publication are the sole

responsibility of the authors and can in no way be taken to reflect the views of the European Union”

https://ec.europa.eu/programmes/horizon2020/

P u b l i c 2 of 53 | P a g e

DOCUMENT SUMMARY

Deliverable Title Evaluation Report Rapid Manufacturing of Customised Designs

Due Date Month 8 (30/04/2016)

Version Final

Deliverable Type REPORT

Deliverable Lead UPB

Related Work package WP 4

Author(s) Ulrich Jahnke, Thomas Reiher, Suny Martínez

Reviewer(s) John Mulcahy

Contributor(s) All partners

Communication level PU Public

PP Restricted to other programme participants

(including the Commission Services)

RE Restricted to a group specified by the consortium


CO Confidential, only for members of the consortium


Grant Agreement Number 646167

Programme H2020-NMP -2014-2015

Start date of Project 01/09/2015

Duration 48 months

Project coordinator UNIVERSITY OF LIMERICK

DOCUMENT HISTORY

Issue Date Version Changes Made / Reason for this Issue

01/12/2015 V0.1 Initial Version

25/04/2016 V0.2 Draft Version

29/04/2016 V1.0 Finalised Version

23/05/2016 V1.1 Reviewed version by AIJU

21/07/2016 V1.2 Additional Update including Rapid Tooling

15/09/2016 V2.0 Finalised Updated Version


TABLE OF CONTENTS

TABLE OF CONTENTS ........................................................................................................................................... 3

ABSTRACT ............................................................................................................................................................ 4

1. INTRODUCTION ........................................................................................................................................ 5

1.1 iBUS Rationale .................................................................................................................................. 5

1.2 iBUS Approach .................................................................................................................................. 5

1.3 GOALS OF WP4 MAKE ...................................................................................................................... 6

2. Requirements for rapid manufacturing of customised designs ..................................................... 7

3. Description of techniques ...................................................................................................................... 9

3.1 Conventional manufacturing techniques relevant for iBUS project .................................... 10

3.2 Additive Manufacturing ................................................................................................................ 18

3.3 Rapid Tooling techniques ............................................................................................................ 34

3.4 Rapid manufacturing tools .......................................................................................................... 39

4. Review Portfolio of Rapid Manufacturing of customised designs ............................................... 43

4.1 Information collection .................................................................................................................. 43

4.2 Review portfolio of Conventional Manufacturing techniques .............................................. 49

4.3 Review portfolio of Additive Manufacturing techniques ....................................................... 49

4.4 Review portfolio of Rapid Tooling techniques ........................................................................ 50

4.5 Decision support table assessing manufacturing techniques .............................................. 51

5. References ............................................................................................................................................... 52


ABSTRACT

The “Evaluation Report Rapid Manufacturing of customised designs” is the reference document

for further tasks and decisions to be made in the iBUS project by the consortium. To achieve the

goals of WP4 in an efficient and effective way this report will contain information about

techniques for manufacturing of customised designs that are available in the iBUS project. The

present document is structured in different sections describing suitable techniques in general and

showing detailed information and feelings about techniques used by iBUS consortium. This

information has been collected by questionnaires answered by iBUS consortium members. The

guideline how to deal with the questionnaire explaining the main aim and the criteria to be

assessed are described as well to achieve a common understanding.


1. INTRODUCTION

iBUS “integrated business model for customer driven custom product supply chain” is a European Union’s Horizon 2020 research and innovation programme funded under grant agreement No 646167. The call, NMP-35-2014 is an innovation action whose aim is to support new Business models with new supply chains for sustainable customer-driven small series production. The new iBUS model will enable consumers to become designers and "customisers"; retailers to become virtual business brokers; manufacturers to produce in a distributed and small scale manner; and suppliers to be more flexible and demand-driven

1.1 iBUS Rationale

Ever since the industrial revolution, society has been able to produce most needed objects for work or play in cost effective ways. However, affordability came with mass production of standardised products. When production costs rose in developed economies, production moved offshore to lower cost economies. This shift in production had unintended impacts on supply availability, quality and the environment. Furthermore, the processes involved in the engineering of mass produced standardised products focused on reducing production costs while the conceptual design processes often limited the creativity and involvement of the customer. There is now a need for new supply chain models, which are cost effective, but also respect European key values for innovation, quality, safety and sustainability. These models need to engage disruptive technologies, to meet economic and sustainability objectives, but also to attract a new generation of young Europeans to careers in manufacturing, revitalizing traditional manufacturing sectors such as toys and furniture.

Today, consumers are rapidly becoming accustomed to personalized choice and customised products. Through the internet and social media, our outlets for self-expression are becoming limitless and instantaneous. Consumers, not only want to customise or personalise their purchase, they want it ‘on-demand’. Today, we can create what we design through new technologies such as additive manufacturing systems including 3D printing. We can think of the object, model it virtually and print it, with remarkable outcomes in short time spans. Exploiting these new technologies as customers and businesses will only be limited by our access to the technologies and our ability to dream.

1.2 iBUS Approach

The overall iBUS goal is to develop and demonstrate, by 2019, an innovative integrated business model, for the sustainable supply and manufacture, within the EU, of traditional toys and nursery furniture.

The successful development of iBUS project is expected to deliver the following goals:

return delocalised manufacturing of traditional toys and furniture to Europe by a minimum of 5% or the total manufacturing capacity within 5 years.

reduce the environmental footprint by at least 20% by establishing a local production, by planning the production according to the demand requirements and by using Additive Manufacturing technologies where appropriate.

create a novel supply network involving at least 100 organisations at the end of the project and 1000 within 5 years after the project

create new embedded services supporting the customer-driven supply chain and the reduction in the environmental footprint


1.3 GOALS OF WP4 MAKE

WP4 will transform the design information coming from the customer into a form that allows the supplier to make the customise design in one-step manufacturing process with minimal administrative burden. This WP will enable the iBUS platform to efficiently and effectively utilise its portfolio of manufacturing suppliers and associated competences with a special emphasis on wood and plastic product families.

Therefore, this Deliverable intends to collect all information on manufacturing capabilities of iBUS partners to clarify availabilities for manufacturing of product samples during project runtime as well as for exploitation and commercial use of iBUS platform. This information are basis for the planning and development of software, data formats, processes, sample parts and invoicing / cost prediction system.


2. Requirements for rapid manufacturing of customised designs

Main aim of the rapid manufacturing of customised design by the iBUS Platform is to bring mass customisation (MC) into the market. Mass customisation refers to a business strategy that aims to provide customers with individualised products at near mass production efficiency [PILL04]. Piller 2004 developed twelve prepositions for why mass customisation is not widely spread today. Some of these refer to management or to market capabilities and will be discussed in other workpackages. Regarding the actual manufacturing of customised designs two main hurdles have to be overcome. Beside the enabling technologies for mass customization as well the customer needs have to be elicited in a simple and direct way and communicated to the production facilities.

From the firm’s perspective, the costs of mass customization include two factors: (i) the cost of providing high flexibility in manufacturing, and (ii) the cost of eliciting customer preferences. Till today, mass customization research and practice is closely connected to the first factor, i.e., the potential offered by new manufacturing technologies to reduce the trade-off between variety and productivity (Ahlström and Westbrook, 1999; Fogliatto, Da Silveira, and Royer, 2003; Kotha, 1995; Pine, 1993a; Thoben, 2003; Victor and Boynton, 1998). But if a firm cannot transfer the customers’ preferences cheaply into a fitting product design, the best available manufacturing technology is of no meaning (Reichwald, Piller, and Moeslein, 2000). In a co-design system, the solution space, i.e., the product architectures and the range of possible variety, is fixed during a preliminary design process (autonomously by the firm). But a second step takes place in close interaction between the customer and the manufacturer, the elicitation process of mass customization (Zipkin, 2001). The costs arising from customization broadly comprise interaction and information costs. They are accounted for by the investigation and specification of the customers’ demands, the configuration of individual products, the transfer of the specifications to manufacturing, an increased complexity in production planning and control, the coordination with the suppliers involved in the individual prefabrication and the direct distribution of the goods. [PILL04]

Mass customization is only possible if flexible manufacturing processes are supported by adequate systems for customer co-design. These systems are known as configurators, choice boards, design systems, toolkits, or co-design-platforms. They are responsible for guiding the user through the configuration process. Different variants are represented, visualized, assessed, and priced with an accompanying learning-by-doing process for the user [von Hippel, 2001 in Piller 2004]. Such a system will be developed by the iBUS consortium with launch of iBUS platform in “WP3 Customised Product Design Virtual Environment”. This system will have the need to give a possibility for the customer to express its needs and wishes. Following [PILL15] the customer has to be supported in finding his product. Otherwise the “paradox of choice” leads to a reduced value for customer if he has too many choices and is not led in decision process. Furthermore, the dataset of cosutomized product has to be transferred into production orders for different techniques. This step is highly important as a cost and time efficient manufacturing of customised designs is only feasible if the customer needs can be transferred to a physical product with minimal administrative burden. Therefore, a preferably direct manufacturing technology is needed. For example, the design and manufacturing of a special, customised mould for injection moulding is expected not to be feasible due to high costs and time consumption.

Figure 1 shows the process of rapid manufacturing of customized designs. In the first step the customer needs are combined with design information coming from a design database. Thereby the customised design data is created which will then be manufactured. For the manufacturing three main paths are considerable, depending on the batch size. Customized design may either be produced in batch size one, a low batch size or even a combination with uncustomised high batch elements.


The main requirement for an economically successful rapid manufacturing of customised designs is to enable fast design changes. This is only possible if the following requirements are fulfilled:

- Switch of design: the switch between two different designs manufactured has to be made pretty fast and easy. For example, the change of a big and heavy mould for an injection moulding machine and the subsequent determination of shot size and heating/cooling time for high quality results may be very time consuming.

- Preparation of next shot: a cost efficient production needs to be able to produce a lot of elements in a short time. Therefore, the unproductive machine time between two produced parts is important. For example, injection moulding can be very fast in production of high batch production while for FLM labour work is needed between each build job what may hamper a fast production.

- Flexible material change: if there is a high number of different customised designs with e.g. different colours shall be produced, it might be required to change the material very often. This might be faster for FLM or milling than for injection moulding.

- Automated generation of machine code: the code for machine control should be created automatically as use of labour time would take a long time and would be very cost ineffective.

iBUS

Platform

(Co-Design)

Customer needs

Design information

Database

rawdesign

Customised

Design DataManufacturing

decision

Automatic

production

start

Customised

product

one

Highbrid

Manufacturing

preparation

Combination

of elements

low high

LQ-mould

manufacturing

Manufacturing

preparation

HQ-mould

manufacturing

High batch

elements

Automatic production start

Production

Low batch,

customised elements

Production

Machine code

generation

Design and

Material change

Figure 1: Rapid manufacturing of customized design process


3. Description of techniques

DIN 8580 suggests a separation of manufacturing technologies into six different main groups:

1. Moulding 2. Forming 3. Separating 4. Joining 5. Coating 6. Altering material properties

This subdivision is useful for conventional manufacturing but does not separate AM clearly from the others. For a better differentiation this is often grouped to only three areas:

a) Subtractive technologies b) Shaping technologies c) Additive technologies

Subtractive technologies achieve the desired geometry by removing defined areas of a part’s material. A shaping technology models a given volume to the desired geometry by retaining the volume constancy while AM merges volume elements in a layer wise production. [Gebh13] [Burn93]. Therefore, the following figure shows a classification of manufacturing techniques based on these three areas. As additive manufacturing is one technique often mentioned as a driver for mass customisation and therefore focused in the iBUS project this approach is more feasible.

Figure 2: Classification of manufacturing techniques

Manufacturing

Shaping

Cold Forming

Hot Forming

Sustractive

Milling

Turning

Drilling

Additive

VAT Photopolymeraisation

Binder Jetting

Material Extrusion

Powder Bed Fusion

Sheet Lamination


3.1 Conventional manufacturing techniques relevant for iBUS project

3.1.1 Subtractive manufacturing techniques

Also known as machining, plays an important role for manufacturing of metal products as well as wood, plastic, ceramic and composites ones.

It comprises various processes that cut a block of raw material into the desired final shape and size by a controlled material-removal process. This controlled material removal is normally carried out by computer numerical control (CNC).

Depending on their characteristics, the machining processes are classified into three principal categories: turning, drilling and milling.

3.1.1.1 Turning

This is a material removal process, which produce rotational typically axi-symmetric parts that can have many features (holes, threads, tapers, various diameter steps, and even contoured machined surfaces).

The turning process requires a turning machine (called lathe) as well as the workpiece, fixtures, and the cutting tool used to shape the object.

The workpiece is a piece of raw or pre-shaped material that is secured to the fixture, which itself is attached to the turning machine, and allowed to rotate at high speeds. The cutter tool is typically a single-point cutting tool although some operations make use of multi-point tools. The cutting tool is moved forward the rotating workpiece to create the desired shape.

A lathe, the oldest and most common type of turning machine, holds and rotates metal or wood while a cutting tool shapes the material. The tool may be moved parallel to or across the direction of rotation to form parts that have a cylindrical or conical shape or to cut threads. With special attachments, a lathe may also be used to produce flat surfaces, as a milling machine does, or it may drill or bore holes in the workpiece.

3.1.1.2 Milling

Milling is the most common technique used for machining. It can create a variety of features on a part by cutting away the unwanted material by rotating the cutting tool in order to bring cutting edges to bear against the workpiece. Milling machines are the principal machine tool used in milling.

It is normally employed to manufacture objects which do not have axial symmetry as well as to include many features such as holes, slots, pockets, and even three dimensional surface contours. This technique is also commonly used in the fabrication of tooling for other processes.

In a milling machine, a workpiece is fed against a circular device with a series of cutting edges on its circumference. The workpiece is held on a table that controls the feed against the cutter. The table conventionally had three possible movements: longitudinal, horizontal, and vertical. Modern milling machines, such as routers, use robotic arms and can be up to 9 - axis.


Milling machines are the most versatile of all machine tools. Flat or contoured surfaces may be machined with excellent finish and accuracy. Angles, slots, gear teeth, and recess cuts can be made by using various cutters.

3.1.1.3 Drilling

Hole-making operations, generally known as drilling operations, group together a collection of machining techniques, whose purpose is to cut a hole into a workpiece.

The material is eliminated by moving a rotating cutter with cutting edges into the workpiece. Hole-making can be performed on a variety of machines, including general drill presses, mills, lathes, machining equipment such as CNC milling machines or CNC turning machines as well as specialized equipment.

3.1.2 Forming

Forming processes englobe those manufacturing processes in which forces are applied to the part to generate intended stresses with the intention of modifying its geometry by causing plastic deformation. These stresses could be: compression, tension, shear or combined. [PHEM96]

The applied force stresses the metal beyond its yield strength, causing the material to plastically deform, but not to fail. During this process no material is removed but deformed.

Formative manufacturing or forming manufacturing techniques has been broadly classified into 2 groups: cold forming and hot forming. [CHAH06]

Cold Forming

With these techniques the part is shaped by applying pressure without applying heat. This process is mainly used with metal parts. Examples: pressing, stamping, forging. [DAKOS93]

Forming

Cold forming

Pressing

Stamping

Forging

Hot forming

Injection moulding

Blow moulding

Thermoforming

Extrusion


Hot forming

It is the most used process for manufacturing plastic products. The process consists of different techniques that convert the material into desired shape by applying pressure and heat to the material. Each of these methods has advantages as well as disadvantages, and its suitability will depend on the specific applications. [DAKOS93]

The more representative methods are:

- Injection moulding

- Blow moulding

- Thermoforming

- Extrusion.

3.1.2.1 Injection Molding

The main method used for processing plastic as it is a fast process and can be used to produce large numbers of identical items going from high precision engineering components to disposable consumer goods.

This technique works as follows: the plastic is placed into a hopper, which then feeds the plastic into a heated injection unit. Afterwards it is pushed through a long chamber with a reciprocating screw. At this point the plastic material softens until it achieves a fluid state. [YEMA11]

A nozzle is located at the end of the chamber. The plastic material in fluid stat is forced to pass through the nozzle into the mould. A system of clamps hold the halves of the mould shut. When the plastic is cooled and solidified, the halves open and the finished product is ejected from it using hydraulic pins. This technique leaves some marks on the surface: a “sprue” where the plastic enters the mould as well as smooth circular marks left by the ejector pins.

There are some variations to this technique available in the market: injection moulding and injection moulding (gas assisted) are the main references.

Thermoplastics are the most material common used for this technique. On the other hand, thermosetting materials are not processed with injection moulding due to the fact that once they soften, if they cool down they would harden to an infusible state. If they are processed with injection moulding, it is mandatory that they are moved as quickly as possible through the heating chamber so as not to set.

Example of typical materials used: Acrylonitrile-Butadiene-Styrene (ABS), Nylon (PA), Polycarbonate (PC), Polypropylene (PP) and Polystyrene (GPPS) [AESS15] [CHAH00].

One of its biggest advantages is the extremely good surface finish (1 - 32 μin) which eliminates most of the

post-processing needed with other techniques. The tooling cost, due to equipment specially the moulds, is high (around 400.000$ of aggregate cost) and therefore the production volume needs to be high (between 1000 and 1 million) too in order to be economically viable Due to its nature lead times could go from long (weeks) to very long (months).


Advantages [YEMA11]

- Able of complex shapes and fine details (± 0.002 in).

- Excellent surface finish (1 - 32 μin).

- Good dimensional accuracy.

- High production rate (1000 – 1.000.000)

- High automatized (low labour cost).

- Recyclable scrap.

Disadvantages [YEMA11]:

- Only thin walled parts.

- High aggregate (tooling + equipment) cost (around 400.000$).

- Long lead time possible (from weeks to months).

3.1.2.2 Blow Moulding

This technique is used for the production in large quantities of articles which are hollow, usually with openings of smaller diameter compared to the body, such as bottles or containers of superior visual and dimensional quality compared to other techniques (mainly extrusion blow moulding). Small products may include bottles for water, liquid soap, shampoo, motor oil, and milk, while larger containers include plastic drums, tubs, and storage tanks. [YEMA11]

The raw material, normally a thermoplastic in the form of small pellets or granules, is first melted and formed into a hollow tube, called the parison. There are various sub techniques depending on how the parison is made:

- Extrusion blow moulding:

This is the most common type of blow moulding and is used to manufacture large quantities of relatively simple parts.

An extruder uses a rotating screw to force the molten plastic through a die head that forms the parison around a blow pin. The parison is extruded vertically between the two open mould halves, so it is possible for them to close on the parison and blow pin. Pressurized air flows through the blow pin to inflate the parison until the final shaped is achieved.

- Injection blow moulding:

This is the least commonly used method because of the lower production rate, but is capable of forming more complicated parts with higher accuracy. Injection blow moulding is often preferred for small, complex bottles (medical applications).

The molten plastic is injected around a core inside a parison mould to form the hollow parison. When the parison mould opens, both the parison and core are transferred to the blow mold and securely clamped. The core then opens and allows pressurized air to inflate the parison.

- Stretch blow molding:


It is typically used to create parts that must withstand some internal pressure or be very durable, such as bottles.

The parison is formed in the same exact way as injection blow moulding. Nevertheless, once it is moved into the blow mould, it is heated and stretched downward by the core before being inflated. This stretching provides greater strength to the material.

The parison is then clamped between two mould halves and inflated by pressurized air until it fills the mould and conforms to the inner shape of the mould cavity. Typical pressures are far less than for injection moulding (from 25 to 150psi). Afterwards it is left to cold down until it reaches a safe temperature to be manipulated. Finally, the mould halves are separated and the part is ejected using a hydraulic system.

Blow moulded parts can be formed from a variety of thermoplastic materials, including the following: Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polyethylene Terephtalate (PET), Polypropylene (PP), Polyvinyl Chloride (PVC) [AESS15] [CHAH00].

As with injection moulding, the tooling and equipment costs are high (aggregate cost 150.000$) and therefore the production volume needs to be high too (generally between 1000 and 1000000) in order to be economically viable. The post-processing needed due to its low surface quality (250 - 500 μin) leads usually to additional cost.

Advantages [YEMA11]:

- Able of complex shapes with uniform wall thickness.

- High production rate (1000 and 1000000).

- Highly automatized (low labour cost)

- Few scrap generated.


- Limited to hollow, thin walled parts with low degree of asymmetry

- Poor control of wall thickness.

- Poor surface finish (250 - 500 μin).

- Limited material options

- High cost aggregate cost (tooling + equipment) 150.000$.

3.1.2.3 Thermoforming

Thermoforming uses a plastic sheet as workpiece, which is transformed into the shape with the mild by applying air or through mechanical assistance. It has a wide range of applications depending on the width of the sheet: Thin-gauge sheets are mostly used for rigid or disposable packaging, mainly food, while thick sheets are typically used for cosmetic permanent surfaces on automobiles, shower enclosures, and electronic equipment. [YEMA11]

During this technique the thermoplastic sheet is heated by an oven using either convection or radiant heat until reaches its softening point and then the sheet is held horizontally over a single-sided mild where the shaping stage takes place.


Different methods can be used to force the thermoplastic sheet to conform to the mould:

- Vacuum forming (0 psi):

A vacuum is formed between the mould cavity and the thermoplastic sheet to forces the sheet to conform to the mould and form the part shape.

- Pressure forming (hundreds of psi)

In addition to utilizing a vacuum underneath the sheet, air pressure is applied on the back side of the sheet to help force it onto the mould allowing the forming of thicker sheets and enabling the creation of finer details such as textures, undercuts, and sharp corners.

- Mechanical forming:

The thermoplastic sheet is mechanically forced into or around the mould by direct contact. Typically, a core plug will push the sheet into the mould cavity and force it into the desired shape. Afterwards it is held in place while it cools and solidifies into the desired shape. Excess material is then trimmed away, which can be reground, mixed with unused plastic, and reformed into new thermoplastic sheets, and the formed part is released.

One of the major advantages of this method is that it has superior surface finish as it does not produce marks on the object [AESS15]. Other big advantage is that neither high heat nor pressure is required so moulds can be made from cheap materials such as MDF or cast aluminium.

Due to its characteristics and requirements the tooling cost is relatively low what enables small batch size or even one offs. Commonly it is used for batch sizes between 1 and 100.000. It can be used together with mechanizing to speed up process.

A vast variety of sheet thermoplastic materials are compatible with this technique. A brief list of them would be: Acrylic (PMMA), Acrylonitrile Butadiene Styrene (ABS), Cellulose Acetate, Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), Polyvinyl Chloride (PVC) [AESS15] [CHAH00].


- Can produce very large parts (0.04 in² - 300 ft²).

- High production rate (1 – 100.000).

- Good Surface finish (16 - 120 μin). - High tolerances (± 0.008 in). - Low cost (compared with other plastic manufacturing techniques).


- Shape complexity is limited.

- Limited wall’s width (0.002 - 0.25 in).

- Non-recyclable scrap.

- Trimming is mandatory.


3.1.2.4 Extrusion

The process of extrusion is usually used to make products with a constant cross section: such as films, profiles, continuous sheeting, tubes, profile shapes, rods, coat wire, filaments, cords, and cables.

As with injection moulding, dry plastic material is placed into a hopper and fed into a long heating chamber. At the end of the chamber, however, the material is forced out of a small opening or a die in the shape of the desired finished product. As the plastic exits the die, it is placed on a conveyor belt where it is cooled down. Blowers can be used as well as immersing in water to aid in this process of cooling down.

This technique is compatible with a wide range and variety of plastics, nearly anyone in the market. It is especially used with high density polythene; polystyrene and polyvinyl chloride as well as with synthetic fibres [AESS15] [CHAH00].

One of the major advantages is that this technique produces no marks on the finished products. On the other hand, it can have expansion – contraction issues as it is complex to predict the final dimensions.

Due to the die required for the profile the aggregate cost can vary around a moderate quantity (between 50.000 and 250.000). Therefore, production volume is high but is restricted to a minimum order size.


- High automatized (low labour cost).

- Good surface finish (30 - 100 μin).

- Few scrap generated.

- High production volumes (500 – 2000kg/h).

- Moderate cost per meter / pound.

- Wide range of compatible materials.

- Compatible with compound materials.


Product limitations: Only uniform cross-sectional shapes.

3.1.3 Customization capability of conventional manufacturing techniques

Thinking about customization capabilities of conventional manufacturing techniques forming and subtractive techniques offers completely different potentials. While forming techniqes require tooling more effort is needed for small batch or even single piece production. Therefore, in the following section the main focus lays on subtractive machining. As an application of forming techniques for customized production is generally possible but depending on tools or moulds this will be described and discussed in section 3.4 and 4.4 “rapid tooling techniques”.

Parts that are fabricated completely through milling often include components that are used in limited quantities, for instance for prototypes such as custom designed fasteners or brackets. Another application of milling is the fabrication of tooling for other processes. This can be done to add features that were too costly to form during the primary process or to improve the tolerance or surface finish of existing holes. Milling is


also commonly used as a secondary process to add or refine features on parts that were manufactured using a different process.

Due to the high tolerances and surface finishes that milling can offer, it is ideal for adding precision features to a part whose basic shape has already been formed. It has a variable batch size, which can go from limited, mainly prototyping, to big batch size (up to 1.000.000 units). The compatible materials are mainly metals such as: alloy steel, carbon steel, cast iron, stainless steel, aluminium, copper, magnesium, zinc, lead, nickel, tin and titanium. Plastics and other materials are processible as well: elastomer, thermoplastics, thermosets as well as ceramics, composites and wood are also compatible with this technique.

The general advantages and disadvantages of choosing machining for a manufacturing process are:

Advantages:

- Wide range of compatible materials.

- Very good tolerances

- Reduced lead times

Disadvantages:

- Limited shape depending on complexity and technique.

- Several operations needed depending on the complexity

- High investment in equipment

- Notable tool wear

- Scrap generated

In this section we will focus on the mechanizing techniques applied to plastic materials.

In the case of plastics, machining tends to lend itself better to rigid materials, such as fibre reinforced thermosetting plastics materials, glass reinforced nylons, acrylic or PEEK have good relative stiffness. Less rigid plastic tends to deform and bend away when the cutter attempts to cut the component, making the achievement of fine dimensional tolerances difficult.

Advantages of Machining Plastics - No mould needed.

- Reduced lead times.

- Lower economically viable batch size.

- Prototyping compatible.

- Thicker wall section.

- Bigger size compared to moulding.

- Low forces required for mechanising.

- Dry mechanising.

- Swarfs can be recycled.

Disadvantages of Machining Plastics Materials - Machining ability limited by materials

- Cost of the block plastic material

- High scrap.


- Difficulties to handle the swarf.

- High costs of CNC machine time.

- Robust jigs and fixtures required for volume production

- Plastics have low heat conductivity.

- Dust collection system needed for some materials.

- Programming time by experienced operator

3.2 Additive Manufacturing

The term Additive Manufacturing is defined by different organizations for standardization like ASTM (F2792) or the German Engineering Association VDI (Guideline 3405) but in a very similar way. For example, according to ASTM and ISO standards (ISO/ASTM 52900:2015), AM is the process of joining materials to make parts or objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing and formative manufacturing methodologies. Besides the term Additive Manufacturing “3D Printing” is increasingly used for the different production technologies. This designation is however viewed critically in the scientific literature as 3D Printing describes explicitly a single powder-binder method. Furthermore, different names are used to describe the processes depending on the time of use in the product development.

resource production

resource development

production

development / elaboration

concept / planning / idea

VD

I 222

1st

ruct

uri

ng

of

AM

-te

chn

olo

gie

s

Figure 3: Processes depending on the time of use in the product development

The industrial product development covers the period from the initial product idea to the presentation of the product on the market. It includes the development of the product, the development and production of production resources, and the manufacturing of the product. The aim of all producers is to keep this period without revenue as short as possible and therefore to optimize the sub-processes.

Additive manufactured components are particularly suitable to accelerate and improve the process of product development due to their production without time-consuming and costly tools. This effect increases if the optimum additive manufacturing technologies are used in each phase of the product development. For this it is advantageous to make the correlation between the additive applications and the phases of product development according to VDI 2221 (Figure 3).

Rapid Prototyping has to be assigned to the product development and Rapid Manufacturing to the manufacturing (means of production and product) (Figure 3, centre). In detail the ideation, planning and


conception is aided by the Concept Modelling and the development and elaboration by the Functional Prototyping. The manufacturing of the products Direct Manufacturing is used. Tools and moulds are realised by rapid tooling (in the prototype phase by Prototype Tooling and in the production phase by Direct Tooling) (Figure 3, below).

Additive Manufacturing Technologies

In addition to the definition of the term Additive Manufacturing also seven subcategories have been determined by ASTM International Committee F42 in January 2012, in which the additive manufacturing processes can be classified. These are

- Material extrusion—an additive manufacturing process in which material is selectively dispensed through a nozzle or orifice,

- Material jetting—an additive manufacturing process in which droplets of build material are selectively deposited,

- Binder jetting—an additive manufacturing process in which a liquid bonding agent is selectively

deposited to join powder materials,

- Sheet lamination—an additive manufacturing process in which sheets of material are bonded to form

an object,

- Vat photo polymerization—an additive manufacturing process in which liquid photopolymer in a vat

is selectively cured by light-activated polymerization - Powder bed fusion—an additive manufacturing process in which thermal energy selectively fuses

regions of a powder bed and

- Directed energy deposition—an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as the material is being deposited.

All of these additive manufacturing technologies have the layered structure in common by definition. Beyond this, however, they combine other common characteristics. The generation of the geometry results with all AM methods directly from 3D CAD data and all machines now on the market can be controlled by the same (STL) file. Additive Manufacturing thus ensures the direct conversion from the virtual (3D CAD data) to the physical component. Further, the additive manufacturing process is characterized by tool less production of products as well as by the generation of the mechanical-technological properties (material properties) during the construction process. A final further characteristic of all AM-technologies is the production of parts in any orientation. This eliminates the clamping problem of many conventional methods. The properties of some commercially established methods are described below.


Stereolithography (SL)

1 coater 6 liquid resin (polymer bath) 2 laser 7 support structure 3 solidification zone (polymerisation) 8 build tray 4 X-Y scanner 9 build platform with retractable table 5 generated part

Building process layer-by-layer additive technique in which synthetic photopolymer resins (pre-polymers with photo-activators) selectively cure, or solidify, when exposed to a laser beam

Source material liquid or paste: UV-activated synthetic resin with or without filler

Binding mechanism chemical (covalent bonding)

Material processing method vector-oriented

Activation energy UV radiation from lasers and lamps

Post-processing cleaning; cross-linking/curing in the UV oven

This system uses a vat of curable photopolymer resin. The liquid polymer is polymerized by exposing it to a single laser (UV laser in SLA technology) or optics. This system draws a cross section layer by layer. After each layer, the object is pulled up which creates space for the uncured resin at the bottom of the container and can then form the next layer of the object. The process is repeated until a model has been created. Another method consists of pulling it downward into the tank with the next layer being cured on the top [SRSU2015].

Blades or recoating blades can be pass over between layers to provide a smooth resin base and to ensure that there are no defects in the resin for the construction of the next layer.

One important point is that, as the process uses liquid to form objects, there is no structural support from the material during the build phase, unlike powder based methods. If necessary support structures should to be added.


Stereolithography requires post processing on a regular basis: Once excess resin is drained from the vat, parts must be removed. In order not to contaminate the unused resin, the operator must be cautious and must take appropriate safety precautions. The general method for removing resin consist of an alcohol rinse followed by a water rinse. A final post cure process is usually employed to enhance the quality of the object [GUYA15].

The main strong points for this technology is its accuracy and the excellent surface finish. On the other hand, depending on the material, models can be brittle. Typical layer thickness for the process are between 0.025 – 0.5mm.

The Vat polymerisation process uses plastics and polymers, specifically UV-curable photopolymer resins.

Advantages [GAFB87]:

- High level of accuracy. - Good surface finish. - Relatively quick process. - Typically large build areas (example 1500 x 750 x 550mm).

Disadvantages [GAFB87]:

- Material relatively expensive. - Requires post processing for removing the resin. - Limited material use of photo-resins. - Support structures and post curing are often necessary. - Brittle models.


Laser sintering (LS)

Laser sintering (LS) is also referred to as selective laser sintering (SLS®).

1 coater with powder delivery system 6 generated part 2 powder storage tank 7 support structure 3 CO2 laser 8 overflow tank 4 X-Y scanner 9 retractable table 5 solidification zone

Building process layer-by-layer additive technique in which powdered material is selectively melted, or sintered, when exposed to a laser beam

Source material powder: particle-reinforced polymers, polymer compounds, metal alloys, ceramics with fillers or binders

Binding mechanism physical (thermal)


Activation energy heating by lasers and lamps

Post-processing controlled cooling, compressed air cleaning post-processing to improve surface finish:

vibratory finishing (barrel finishing)

abrasive blasting

coating

Laser sintering is a 3D printing technique whose basic concept is similar to SLA: an object is created by melting through a moving laser beam successive layers of powder together in order to form successive cross-sections of a three-dimensional part. Parts are created on top of a platform that adjusts in height equal to the thickness


of the layer being built. Additional powder for the next layer is deposited by a roller on top of each solidified layer [SRSU2015].

The process most notably advantages are the creation of complex and interlocking forms, as well as its surface quality additionally to the fact that special support structures are not required as the excess powder material in each layer provides adequate model support to the part being built. In contrast, as drawback should be highlighted, that the design cannot be solid and should contain holes to evacuate the unutilized powder [GUYA15].

The build platform is commonly located is within a temperature controlled chamber, where the temperature is usually a few degrees below the powder’s melting point, making it easier to fuse layers together when exposed to the laser.

This method requires post processing to remove excess powder and further cleaning. Overall process time is increased as models require a cool down period to ensure a high tolerance.

This technique is compatible with any powder-based materials, commonly metals and polymers, although the exact material compatibility depends on the technique employed. This wide range of materials includes nylon, glass-filled nylon, rubber-like materials [EAAS12].

Typical layer thickness varies from 0.08 - 0.15 mm.¡ with an average printing speed of 2 litres /hr.


- Relatively inexpensive - Suitable for visual models and prototypes. - Powder acts as an integrated support structure. - Wide range of material available.


- Relatively slow speed. - Structural properties depend on powder grain size and process. - Surface finish depends on powder grain size and process.

- Size limitations. - High power usage.


Laser beam melting (LBM)

Also referred to as laser forming, selective laser melting (SLM®), LaserCUSING® and direct metal laser sintering (DMLS®). A similar process to LS for fabricating metal parts by fully melting the material (welding).

1 X-Y scanner 5 build tray 2 solidification zone 6 build platform with retractable table 3 generated part 7 coater with powder delivery system 4 support structure

Building process layer-by-layer additive technique which utilises lasers to selectively melt powdered materials which then fuse during solidification

Source material powder: usually metal alloys



Activation energy heating by laser

Post-processing post-processing to improve surface finish:

vibratory finishing (barrel finishing)

abrasive blasting

coating


Electron beam melting (EBM®)

A similar process to laser sintering (Section 5.2.2) and laser beam melting (Section 5.2.3) for fabricating metal parts by fully melting the material.

1 coater 6 solidification zone 2 powder storage tank 7 generated part 3 electron beam generator 8 support structure 4 focussing coil 9 build tray 5 deflection coil 10 build platform with retractable table

Building process layer-by-layer additive technique which utilises an electron beam to selectively melt powdered materials which then fuse during solidification

Source material powder: usually metal alloys



Activation energy kinetic energy of electrons

Post-processing Post-processing to improve surface finish


Fused layer modelling/manufacturing – FLM

Also referred to as fused deposition modelling (FDM®) and filament deposition.

1 heated nozzles 5 build tray 2 linear application 6 build platform with retractable table 3 generated part 7 material stock: coiled filament 4 support structure

Building process layer-by-layer additive technique in which a thermoplastic material is softened and selectively deposited through a heated nozzle or print head; the material solidifies immediately after extrusion; each successive layer may be milled or not, depending on the technology

Source material filament: one or two different polymers (part material and support structure) with or without filler



Activation energy heating of the nozzle/print head to soften/melt the source material

Post-processing Removal of support structure mechanically or using lyes; cleaning; coating

Fused deposition modelling (FDM) is a common material extrusion process and is a trade mark of the company Stratasys, the generic name is fused filament fabrication (FFF). It is considered to be the entrance level technology for amateur customers as it is the most affordable 3d printing system compared to others. There are a huge number of printers available on the market [SRSU2015].

This process works as follows: The material is melted and extruded through a nozzle in order to print a cross section of an object, one layer at a time. The bed lowers for each new layer and this process repeats until the object is completed. The material extruded under constant pressure and in a continuous stream. This pressure


must be kept steady and at a constant speed to enable accurate results. Material layers can be bonded by temperature control, mechanical actuators or through the use of chemical agents [GUYA15].

Some 3D printers have two or more print heads to print in multiple colours or support material.

The process has many factors that influence the final model quality which, if are controlled successfully, led to a great end product. Layer thickness determines the quality of the 3D print and it depends directly on the diameter of the nozzle. Gravity and surface tension of the material must be accounted when high tolerance is required. Typical layer thickness varies from 0.178 mm – 0.356 mm.

Among all the materials used in the material extrusion technology, the most known are: ABS, PLA, AB, HIPS, PVA, Nylon, PET, PETT, Polycarbonate (PC), TPE.


- Relatively inexpensive process. - Materials with good structural properties are easily accessible. - Multimaterial compatible.


- Final surface quality depends mainly on the nozzle diameter. - Final quality depends on many factors. - Relatively slow. - Support structures are mandatory. - Shrink-age must be taken into account. - Accuracy and speed are low when compared to other processes. - Constant pressure of material is required in order to increase quality of finish


Multi-jet modelling (MJM)

1 material feed from heated storage container 4 part 2 heated print heads 5 support structure 3 linear application of melted material 6 build platform with retractable table

Building process layer-by-layer additive technique in which thermoplastic materials are melted and linearly deposited through heated nozzles: material hardens on impact

Source material waxes (low-viscosity polymers)


Material processing method grid-oriented

Activation energy heating of the print heads to melt/ liquefy the source material

Post-processing mechanical removal of support structures


Poly-jet modelling (PJM)

1 print heads 5 support structure 2 UV beam 6 build tray 3 solidification zone (polymerisation) 7 build platform with retractable table 4 generated part

Building process layer-by-layer additive technique in which liquid photopolymer resins (polymers with photo-activators) are deposited line-by-line and immediately harden on exposure to UV radiation; multi-material applications can be achieved by blending materials during the build process

Source material liquid/paste-like: support and modelling material (different polymer blends to govern the material characteristics)

Binding mechanism chemical (UV cross-linkage)


Activation energy heating of the print heads to melt the source material UV radiation for post-curing

Post-processing cleaning with water jets to remove support structure


3D printing (3DP)

1 coater 5 generated part 2 powder storage tank 6 support structure 3 dot-by-dot binder application 7 overflow container 4 print heads 8 build platform with retractable table

Building process layer-by-layer additive technique in which a binder is deposited dot-by-dot onto a powder bed, or co-polymerisation of powdered material

Source material Powder: powder mixes (inorganic powder (gyp-sum), polymers, metal, ceramics, etc.) liquid: binder

Binding mechanism physical (thermal) and/or chemical (cross-linkage)

Material processing method vector- or grid-oriented

Activation energy none

Post-processing controlled cooling, compressed air cleaning impregnation with liquid hot wax or infiltration with epoxy resin or adhesive; necessary to increase mechanical resistance; sintering (ceramics)


Layer laminated manufacturing (LLM)

Layer laminated manufacturing (LLM) is also referred to as laminated object manufacturing (LOM™).

1 laser 6 laminator roll 2 cutting point 7 film strip 3 residue take-up roll 8 raw material 4 generated part 9 build tray 5 X-Y scanner 10 build platform with retractable table

Building process layer-by-layer additive technique in which contoured layers of material are cut out using a laser, knife or water jet, then bonded, or fused by ultrasound

Source material prefabricated sheets of paper, plastic, metal or ceramic

Binding mechanism thermal or thermochemical


Activation energy application of heat to melt the hot glue to bond the layers or use of suitable fusing process to bond the layers

Post-processing removal of waste non-part area finishing (painting or coating) if necessary, sintering


Digital light processing (DLP)

A similar process to stereolithography which uses a lamp and mask.

1 build platform with retractable table 6 vat filled with photopolymer 2 build tray 7 glass plate 3 support structure 8 tilted mirror 4 generated part 9 UV lamp 5 burning point

Building process layer-by-layer additive technique in which liquid photopolymer resins (polymers with photoactivators) are selectively cured when exposed to a light mask (controlled by micro-mirrors or deflected laser beams)

Source material liquid or paste: UV-activated synthetic resins (oli-gomers/monomers) without or with fillers

Binding mechanism chemical (cross-linkage)


Activation energy UV radiation; wavelength matched to synthetic resin (targeted radiation source to process the material)

Post-processing chemical cleaning


Thermal transfer sintering (TTS)

1 coater for powder application 5 generated part 2 material delivery system 6 powder bed 3 solidification zone 7 overflow container 4 heated print head 8 vertically movable build platform

Building process layer-by-layer additive technique in which powdered material is selectively melted, or sintered, when exposed to thermal radiation (thermal transfer print head)

Source material powder: non-reinforced polymers, polymer compounds



Activation energy thermal radiation of thermal transfer print head

Post-processing compressed air cleaning


3.3 Rapid Tooling techniques

Rapid tooling in general names techniques to manufacture moulds and mould inlays for casting and thereby tooling is an indirect manufacturing technology. It is mainly used to produce new casting parts very fast without time consuming conventional manufacturing of the mould and furthermore enables more complex geometries for free. The need for casting parts instead of direct additive manufactured parts might be the use of a material that is not capable of being produced by AM or the need of comparable chemical and structural properties. For example, FDM-parts might be critical for children safety if the different layers are not connected safe enough and a delamination could occur resulting in a broken toy.

Also, in the development of new toys or childcare products is extremely important to validate the functionality of the design and product safety. This requires making a small series of each product (usually consists of several pieces) with the final plastic material to be used in industrial manufacturing, thus, it will ensure almost completely fulfilling the final safety and other specifications of mechanical resistance, thermal, chemical, processing, performance, design, etc. As these articles or initial prototypes are usually obtained by injection molding, the manufacturing of a prototype mold (usually a steel or aluminum one cavity mould) is necessary. The use of AM technologies and other rapid tooling techniques for producing the mould and a short run of parts can reduce both cost and time compared to conventional manufacturing techniques.

Since 1998 AIJU has developed funded research projects (national and European) and services for companies regarding the development of new materials formulations for AM and 3D printing technologies, prototype moulds, improvements in processes, etc. An important application of 3D printing in AIJU is product customization and manufacturing unique final parts and prototype moulds with the aim of achieving small print runs with the final material.

One of the projects developed with an injection moulding company was the manufacturing of a part of the mould of a packaging by SLM technology (selective laser melting), with steel material. An already machined steel block of part of the mould was placed into the SLM machine and the rest of the insert was fabricated on the placed block with conformal cooling channels, designed according to the geometry of the part, a circular and tall container. The purpose was to reduce the cycle time as this was a product with large production runs. The use of SLM inserts enabled uniform distribution of temperatures in the mould, not possible when straight channels are manufactured. In this case conformal cooling was worthy as the product has deep regions which


linear cooling channels cannot archive reasonable hot transfer, as stated by S. Marques et al.1 There are many other studies that developed similar solutions for injection moulding2.

Another two projects developed for a thermoforming company was the manufacturing of an insert by 3D printing Objet Polyjet technology with acrylic resins for thermoforming also packaging products (Digital ABS 3D printing material is strong enough to hold up to short injection molding runs of about 10 to 100 parts3). The polymeric insert was designed to be coupled to the mould carrier plates of the thermoforming machine for manufacturing parts with deep geometries and different materials.

Finally, a current project is being developed with a manufacturer of childcare products to obtain pacifiers. Prototypes are most useful when they’re made of the same plastic as the final production part4. Different inserts of injection moulds are being manufactured by 3D printing Objet Polyjet technology with the objective of having prototypes of pacifiers to test according the safety standards before starting the production stage. If the products meet the standards production moulds will be manufactured. AIJU and Stratasys company work closely for giving a correct service to injection moulders for the appropriated design and manufacturing ot that type of inserts.

Figure 4: Rapid Tooling between Rapid Prototyping and Rapid Manufacutring

With regard to a mass customization of casting parts it is feasible to think of products that are made by casting but now get a customization like the face of a doll. The additive manufacturing of mould inlays for the face or head could be a possibility to customize the casting part without high extra costs of a milled mould. A casting production in combination with rapid tooling furthermore enables low cost semi-batch production of

1 S. Marques, A. Fagali de Souza, J. Miranda, I. Yadroitsau. Design of conformal cooling for plastic injection moulding by heat transfer simulation. Polímeros vol.25 no.6 São Carlos Nov./Dec. 2015 http://dx.doi.org/10.1590/0104-1428.2047 2 A. Armillota, R. Baraggi, S. Fassoli. SLM tooling for die casting with conformal cooling channels. International Journal of Advanced Manufacturing Technology 71(1-4) · March 2014 DOI: 10.1007/s00170-013-5523-7 3 http://www.stratasys.com/solutions/additive-manufacturing/injection-molding#sthash.nVG0cryE.dpuf. 4 http://www.stratasys.com/solutions/additive-manufacturing/injection-molding#sthash.nVG0cryE.dpuf

https://www.researchgate.net/journal/0268-3768_International_Journal_of_Advanced_Manufacturing_Technology


customized parts. Hence theses techniques builds the bridge between small batch manufacturing by AM and high batch manufacturing of casting.

Figure 5: Classification of Rapid Tooling

Rapid Tooling (RT) is a natural extension of Additive Manufacturing and Rapid Prototyping in detail. It originated from the need to assess RP models in terms of their performance. To enable performance validation, such models (prototypes) must be produced using the same material and production process as will be used in full-scale production. Furthermore, to facilitate a full range of performance tests, the number of prototypes required may be relatively large. Current RP technologies are neither capable of prototyping in a wide range of commercially available materials nor well suited to producing large numbers of models. This has led to the adoption of multi-step procedures involving various tooling options; such procedures are termed RT. Thus, RT processes complement the RP options by being able to provide higher quantities of models in a wider variety of materials. The importance of RT, however, goes far beyond component performance testing. It is an essential aspect of the more general issue of rapid product development. Traditional methods of producing prototypes are usually skill dependent, expensive and time consuming. This results in a limited number of design iterations and the possibility of incurring further costs at the production stage. On the other hand, it is well known that low-volume products, as well as rapidly changing high-volume products, require quicker and cheaper development procedures to be able to compete on the market. Looking for improvement in this eld, manufacturers and tool makers are exploring different RP techniques. It seems that a major shift from normal prototype tooling practice to RT is underway. Provided that the tools produced by RT are sufficiently durable, there is also scope for them to be employed in the production process. Since the number of RT techniques is increasing, there is a tendency to classify them into groups. Soft tooling is compared with hard tooling, indirect tooling with direct tooling, prototype tooling with production tooling, and so on. The definitions of these groups are not clear, also the borders are not well defined and overlap between their domains is apparent. Despite this, one can suggest a classification of RT techniques based on practical aspects rather than on strict definitions (Fig. 3). The following discussion refers to this classification, concentrating on producing patterns for the foundry industry, using patterns for soft and hard tooling, and manufacturing tools directly on RP machines.


Table 1: Rapid Tooling techniques

Rapid Tooling Method

Lead Time (Days)

Accuracy Types and Quantities of Parts Made

Comment

FDM 1-2 x/y: +/- 0,1mm min. layer thickness: 0,2mm

10-50 Stair stepping effect to be considered as postprocessing is difficult.

Quantity depending on delamination effects

Accuracy based on information by Stratasys for machine type Fortus 400mc

Polyjet 1-2 x/y: 600dpi z: 900dpi

20-80 Very fast, small, agile Good surface Directly usable for molding Accuracy based on

information by Polyjet for machine type Objet30pro

Metal Laser Melting

2-3 x/y: +/- 0,08mm z: 0.02mm

More than spray metal, comparable to conventional moulds

Accuracy based on information by SLM for machine type SLM280HL

Plastics Laser Sintering

3-4 not specified min layer thickness: 0,6mm

Accuracy based on information by EOSP396

Voxeljet 2-3 +/- 0,4% min. +/- layer thickness st. layer-thickness: 0,15mm x/y: 600dpi resolution [VOX16o]

Metals parts 1 Sand casting, very complex forms, agile process

Accuracy based on

information by Voxeljet

Moulding/Ureth ane Casting

3-7 +/-0.002" Polyurethane 15 to 60 Polyurea 10 to 60 Epoxy 10 to 30

Room Temperature Vulcanization (RTV) rubber moulds are the fastest, most


Investment Wax Patterns 50 to 300+ Low Melt Metal Alloy 20 to 75 Polyurethane Foam 0 to 200+ o Silicone Rubber 20 to 80+

accurate, and least xpensive way to create up to a dozen or so duplicates of a prototype partTypically a mould can be shot 1-3 times per day. A single mould can sometimes produce up to 10 pieces at once depending on the part complexity and size

Composite Tooling (Epoxy Tooling)

14-42 +/-0.005" to +/-0.015".

o ABS 50 - 3000 o Acetal 100 - 1000 o Nylon 250 - 3000 o Nylon (Glass filled)50 - 200 o PBT 100 - 500 o PC/ABS blends 100 - 1000 o Polycarbonate 100 - 1000 o Polyethylene 500 - 5000 o Polypropylene 500 - 5000 o Polystyrene 500 - 5000 o Investment Cast. Wax 1000 -10000

The moulding process will have a cycle time of 5 to 15 minutes.

Direct AIM (ACES Injection Moulding)

7-14 0.005" to 0.015"

o aluminium-filled epoxy, 10-100 o ceramics 10-100 o low-melting metals 10-100

Life of the tool is a function of the thermoplastic material and part complexity. Some moulds can create as few as 10 parts, while other can exceed 100. The moulds can have a dynamic failure, but typically gradually degrade with each shot

3D Keltool 14-28 0.005" to 0.015".

100,000 to 10,000,000 shots depending on material

The Keltool part (mould) is limited to 6 inches in all directions. Therefore, any parts produced would be limited to about 4 inches in all directions

Spray Metal Tooling

10-21 Not Reported

o aluminium-filled epoxy, 10-100 o Polyurethane 300 to 20,000 o Polyurea 300 to 20,000 o Epoxy 100 to 600 o Investment Wax Patterns 500 to 10,000 o Low Melt Metal Alloys 100 to 1,500 o Polyurethane Foam 2,000 to 20,000 o Silicone Rubber 10,000+ o Injection Moulding 10 to 1,000 o Rim Moulding 1,000 to 15,000 o Blow Moulding 300 to 500 o Vacuum Forming 5,000 to 100,000

This process applies a zinc/aluminium alloy with an arc spray to a pattern or model. The pattern or model can be a stereo lithography part or a model made from wood or metal. The alloy is sprayed over the pattern to a shell thickness from .060- inches to 0.125-inches as required


3.4 Rapid manufacturing tools

In the following a sample of various machines from the above-described traditional and additive methods are presented. These tools have all in common that they are designed as desktop solutions. So they are optimal suitable for Rapid Manufacturing studios (e. g. 3D print shops).

CARVEY 3D desktop CNC mill

Carvey is a 3D carving machine that allows to make quality objects out of a variety of materials including wood, metal and plastic. By using Carvey and the Carvey Easel design software, it is possible to realise own ideas in three steps. First, the user has to design the product using the Carvey software, next the material has to be chosen and then the product will be carved. Easel is a web-based tool with which parts can be designed in 2D and viewed in 3D.

DIWIRE wire bender

Pensa Labs has developed the DIWire Bender, a desktop CNC wire bender. A new archetype for desktop manufacturing and rapid prototyping, the DIWire transforms drawn curves into bent wire. The DIWire can bend various metals and plastics, allowing for the output to be used as the final product. Additionally, the build volume is limited only by the length of the wire. By being transportable, accessible and affordable, the DIWire fills the market gap

between time-consuming hand-bending and large scale, mass production CNC wire bending, which is too expensive for custom, short-run productions. This changes the dynamics of STEM education, as well as local, mass customized, prototype and just-in-time manufacturing for industries ranging from aerospace, automotive, medical, to consumer products.

GLOWFORGE laser cutter

The Glowforge laser cutter is a desktop solution for cutting and engraving, which is still in development. With it, different materials like natural hardwoods, acrylic, leather or paper can be cutted or engraved. The Glowforge laser cutter comes with a material capability of 30cm x 50cm. The machine’s software runs on a web browser, which means an Internet connection will be necessary to use it.

HANDIBOT portable CNC mill

The Handibot portable cnc mill is a new kind of portable, digitally-controlled power tool for cutting, drilling, carving, and many other machining operations. Instead of taking material to a stationary machine, you bring the Handibot to your material. You can put your Handibot tool to work on a table, the floor, the ceiling, the wall, wherever you need to precisely cut, drill, or carve. Armed with a software application developed just for the kind of job you need to do, a Handibot tool is ready to go to work on your job, task, or project with a squeeze of the “Start” button.


HP MULTIJET FUSION durable powder 3D printer

MJF printers will be capable of having a scalable, and potentially massive, build envelope that can range from 4.25 inches up to 40 inches wide thanks to the easily stackable inkjet arrays. However, HP has not been clear about how tall the 3D printed objects can get, but it would probably be restricted depending on part curing time and the ability to produce support material. MJF 3D printers will be able to control the texture of the part, the level of density or strength, friction, and even be able to give parts electrical and thermal properties.

MAKERARM multipurpose robotic arm

Makerarm is a complete personal fabrication system packed into a single robotic arm that mounts on a desktop. It features interchangeable heads for various applications such as 3D printing, plotting, milling, laser engraving, electronics assembly and more. The robotic arm works with a UI that automatically detects which head is attached, and displays only options and information relevant to that particular functionality. Because it is not confined to a box, it has one of the largest work areas among desktop 3D printers, with a reach of 40 x 80 x 25 cm. It can print with both resin and filament, and with its auto-leveling function, can print and build on any flat surface consistently and reliably.

MCOR ARKE colour paper 3D printer

The desktop 3D printing market has been dominated by FFF (or FDM) filament based 3D printers, with SLA/DLP resin-based printers beginning to catch on, and the first signs of SLS powder-based printers coming to market. The Mcor ARKe uses a technology known as LOM (Laminated Object Manufacturing), where layers of paper are cut into shape, stacked, and glued together. Inside the ARKe, a spool of paper is pulled through the machine to a full colour inkjet head which can print the layers image onto the paper. Next a cutting wheel outlines the desired shape and makes any additional cuts needed. After a layer is complete, it is pressed into the layers below, and a glue binder is applied to prep for the next layer. This method of cutting and gluing also allows for extra material to be added to act as support material that can be easily removed after the print is complete. Because of the paper’s wicking properties, Mcor prints can be post processed with baths to increase the strength or flexibility of the final part.

MINICUT 2D hot wire foam cutter

MiniCut2d uses a hot wire to melt blocks or sheets of foam, turning them into functional objects. It’s a computer controlled machine that works with its own software. The motion of the cutting wire is represented by a single continuous line through the rectangle of the material. With MiniCut2d, users have only to set up the heat of the wire to have a 1mm groove, save it for future usage, and launch the cut. The wire will heat and move and the material will meld on its path.


ORBIT1 desktop electroplating machine

Orbit1 is an electroplater that allows to plate just about everything. Using Orbit1, it is possible to coat 3d printed products in metal or even gold, in three steps. First, clean and polish your object, next spray the conductive paint, then click start. Orbit1 will metallize the design. Applicable to jewellery design, industrial design, rapid prototyping, mechanical parts, specialty electrical parts, moulding/casting kits, and more the Orbit1 is an optimal solution for many different tasks.

POCKET NC portable 5 axis cnc

The Pocket NC is a 5 axis desktop CNC mill. Today, most people are familiar with the concept of Desktop 3D printing which is an additive manufacturing process. The part is built up from the base by adding a layer of material at a time. Milling is a subtractive process where material is removed from a solid piece of stock using a sharp tool to reveal the part inside. While conventional milling machines typically can move in 3 linear axes at a time, the Pocket NC works with 5 axis so that it is possible to machine on multiple faces of the part without having to refixture it.

ROLAND ARM-10 DLP printer

The newly developed desktop ARM-10 3D printer brings together Roland DG’s 3D modelling technologies. It features a proprietary projector lens and Roland’s imageCure resin, creating 3D models using UV light. This acrylic resin becomes semi-transparent when cured. Post-processes, such as support removal, polishing, and adding colour are simple to carry out. With 3D printing, parts which previously required multi-axis milling, such as complex objects with undercuts, can be built quickly and easily. By using a suspended build system, resin consumption is kept to a minimum, making model production efficient and affordable.

ROLAND SRM-20 cnc mill

The SRM-20 is Roland’s latest generation desktop milling machine for the office, studio and educational environment. The SRM-20 incorporates innovative features, including a new spindle, collet, circuit boards and control software. The result is a leap forward in milling precision, speed and ease of use. The SRM-20 can mill a variety of non-proprietary materials typically used for prototyping, including chemical wood, acrylic and modelling wax. Optional collets are also available to extend the mill’s capability with a wide range of end mill shapes and sizes, ideal for creating beautiful finishes and intricate details.

ROLAND VERSASTUDIO BN colour vinyl printer

With the VersaSTUDIO BN-20 it is possible to launch a stream of new businesses from one’s own desktop. The compact professional inkjet can produce durable graphics for outdoor applications, and its Print&Cut capabilities allows to produce labels and decals. Metallic


silver ink is can be used for creating striking effects, and white ink for transparent or coloured media applications.

SILHOUETTE CURIO CNC embossing and cutting

The Silhouette Curio hobby machine is a CNC embossing and cutting machine. It. simply has to be connected to PC or Mac with the included USB cable. It includes the software, Silhouette Studio, to design the project. Afterwards the project-file has to be sent to Curio to emboss or cut various materials.

VERSA UV LEF-20 colour projection on objects

With the LEF-20, small-lot printing on demand is easy to achieve. It is possible to print directly on products and their prototypes, souvenirs, novelty goods, industrial parts, and even consumer electronics items. The LEF-20 features an ink configuration that includes high-quality full-colour printing, plus white and clear inks for premium special effects. Because the integrated UV-LED lamp instantly cure ink during printing, the LEF-20 can print directly onto materials such as PET, ABS, polycarbonate and TPU, as well as soft materials such as leathers and fabrics.

ZORTRAX INVENTURE desktop plastic 3D printer

The Zortrax Inventure is a FFF 3D printer. Its special feature is the Dissolvable Support System (DSS). Users can print objects with soluble supports, offering more possibilities for complicated models with moving parts. The finished print won’t require manual processing; the support material is simply dissolved by immersing the model in water for several hours. The Inventure also features a stable printing temperature within a closed heated chamber.


4. Review Portfolio of Rapid Manufacturing of customised designs

This chapter on the information given by the iBUS consortium. Project partners have been asked about their experiences and availabilities regarding techniques described in the previous chapter. Therefore, the collection and interpretation of information is focused and presented in the following.

4.1 Information collection

For collection of the available techniques in iBUS consortium a questionnaire was used. The questionnaire has been set up as table to be filled by iBUS partners in order to achieve a holistic overview of the techniques and machines available during the iBUS project. iBUS partner provide their information for different categories represented by columns in the table. The meaning, purpose and range of expected answers/units of the different columns are further described in detail in the following sections. The iBUS consortium is asked to enter precise values in “hard fact”-columns and to enter their feelings about the specific issue in “soft fact”-columns.

Column “Available” (hard fact) Please choose one of the options if you are willing to make this technique/machine available for iBUS for production of: - Validation samples during project runtime

- Customized commercial products via iBUS platform

- Both

- None

Important for trials and exploitation. Column “Design change time” (hard fact) Please enter the (estimated) time needed in concrete values or range for: - Start production of a new design (incl. time for tool/mould manufacturing, set-up time)

- Switch to already existing design (tool change)

- Minor changes in design (imagine put different inserts in mould: series doll body + customized heads)

Important to assess feasibility for production of small batch customized designs and to determine economically reasonable batch size & design change frequency. Column “Capable for (mass) customization” (soft fact) Please choose one of the following options about your personal feeling on if this technique/machine is capable for (mass) customization. - Yes

- Already used

- No

Holistic question to summarize all other questions but with a gut feeling. Column “Machine class information” (hard fact) Please enter the class of machine or one representative if a couple of similar machines exist. For AM-machines please add as much information as possible such as exact machine type. This could be part size / weight / etc. producible. For defining product classes for sample part selection in project.


Column “Used period of time (months)” (hard fact) Please enter duration of machine (class) usage in company. Important to assess your knowledge and experience about this process to decide on the complexity / manufacturing challenge possible for parts. Columns “Product Capability” (soft fact) Please choose one of the following options indicating the lowest possible part quality: - End product [high quality]

- Mould [high quality]

- Prototype [low quality]

It is important to determine what the iBUS consortium is able to produce regarding product quality and important for part selection. Column “Requirements” (soft fact) Please choose if this technique / machine is not independent on other techniques. For example, are moulds, semi-finished products (raw material block for milling or turning in the right size) or post processing needed? - Raw material

- Mould

- Semi-finished products

- Post processing

Please choose one or more requirements.

Important to clarify dependencies inside the production chain. Columns “Economical” (hard fact) “Hourly rate [€]”, “Productivity rate [h]”, “investment costs [tendency]” Please indicate the mean - hourly rate for the machine incl. labour

- maximum usable hours per year

- investment costs per machine

Important to determine the costs of a production on this machine. Column “Material” & “Cost per kg” & “Main application” (hard fact) Please indicate the name of possible materials (classes) and the corresponding mean costs per kg. Furthermore, please add the standard application for this material due to specific properties (fire retardant, toxic, etc.) Further information related with the material used to get to know what can be produced for which costs in iBUS for sample parts or commercial products. Column “Pros / Cons / Further comments” (soft fact) Please give some expert knowledge in the free space about the machine, pros and cons and further comments. Needed to take your concerns and advice into account while planning manufacturing and open gaps in iBUS manufacturing capabilities.

The overall questionnaire is shown in a condensed and short version in the following table


Technique

Start production [new]

Capable for

(mass) customis

ation

Product capability

[high quality /

prototypes]

Requirements [raw material / semi-finished

products]

Costs [Hourly rate

[€] / Investment

costs]

Pros & Cons Material Cost per

kg [€] [switch] [mould]

[minor changes] [rapid

tooling] [post processing]

1. Injection Moulding

New 3-6

months

Raw material mainly pellets

20 € Huge machine:

+ High speed production - High investment in moulds - Low flexibility

Polyolefin (PE, PP,

EVA) 2-4 €

Switch < 1 week

Mould

Lab scale machine:

+ low investment in moulds - small part size (<20g)

HIPS, ABS 2-4 € Minor change

2-3 weeks

2. Injection Moulding with RT

New 3-4 days

Raw material mainly pellets for

injection moulding

20 € for injection moulding

+ fast production of mould inserts + fast change of mould inserts - moulds for 20-100 parts + / - equivalent to injection moulding

See injection moulding

2-4 € Switch 1 day Photopolymeric

resin for mould production

Minor Change

2 days

3. Blow

moulding

New 3-5

months

Raw material mainly pellets

20 €

HDPE, LDPE

2-4 € Switch < 1 week

Mould

Minor

change 2-3

weeks Post processing

4. Thermo-forming

New 2 months

Raw material in film

20 €

+ thermoformed pieces + small series of novelties for testing

HIPS

2-3 €

Switch < 1 week

Mould

250 € / sheet

Minor change

2 weeks 1700 € /

m³


Technique


Capable for

(mass) customis

ation

Product capability

[high quality /

prototypes]


products]

Costs [Hourly rate

[€] / Investment

costs]





5. (CNC)

Milling

New 1 month

Semi-finished products

25 € + Accuracy + Easy to use - limitations in complexity - size limitations for some - some old one completely manual

Metals (Al7075;

Steel 2738; Steel 2711; Iron F-114)

7 €

2.7 € 4.5 € 1.6 €

Switch < 1 week

Plastics (PU, ...)

250 € / sheet

Minor change

2 weeks

6. Laser

Sintering

New 1 week

Powder

+ flexible product development + function materials + no support material needed - expensive equipment - accuracy - low surface finishing quality

PA12, PA11, PA+Al,

PA+gf, pp TPE

2-3 €

Switch 1-2 days

250 €

/ sheet

Minor change

1 day Improving

brightness, colours etc.

1700 € / m³

7. Fused

Deposition Modelling

(home machine)

New 1 week

Polymer in Filament Form

+ cheap equipment - low speed manufacturing - low resolution - small parts

ABS PLA PU

AIJU own developed

compounds

Switch 1-2 days

Minor change

1 day polishing

8. Fused

Deposition Modelling (Industrial)

New 1 week

Polymer in Filament Form

+ higher manufacturing speed + high resolution + big parts + high variety of materials - high investment costs

ABS, PLA, AB, HIPS,

PVA, Nylon, PET, PETT,

PC, TPE

Switch 1-2 days

Minor change

1 day polishing


Technique


Capable for

(mass) customis

ation

Product capability

[high quality /

prototypes]


products]

Costs [Hourly rate

[€] / Investment

costs]





9. Photopolymerisation

New 2 weeks

Resins in liquid form

+ Good resolution and accuracy + Good surface finishing + Multimaterial + Excellent reproduction of detail and precision parts + Can create very thin walls - costs of materials - materials restricted to providers - material support needed

Acrylic resins

imitating different thermos-

plastic hardness

250 € Switch 1-2 days

Minor change

2 days

Post-processing for improving bright-

ness, colours, to be more attractive

10. Vacuum Casting

New 4 weeks


+ Versatile for short series + PU resins to imitate wide types of thermoplastics and rubber hardness - Low production speed - Manual technique and skilled people - Silicon moulds cheaper than other processes moulds (i.e. injection moulding…)

PU resins Switch 1-2 days

Minor change

4 days

Post-processing for improving bright-

ness, colours, to be more attractive

11. Stereo-

lithography


+ Accuracy + big sizes + excellent reproduction of detail and precision parts + good surface finish + can create very thin walls + Good resolution and accuracy - price of parts - limited mechanical resistance of materials

Acrylic resins of different charac-teristics:

transparent flexible,

translucent

90 €

Post-processing for improving

brightness, colours, etc. to be more attractive (parts can be painted)


Technique


Capable for

(mass) customis

ation

Product capability

[high quality /

prototypes]


products]

Costs [Hourly rate

[€] / Investment

costs]





12. SDL

+ Low cost + eco friendly + full colour + can be treated

Paper 250 €

Post processing

13. Direct

metal laser sintering

Resins in liquid

form

+ Resistant final metal parts + Inserts and tooling for other processes + Wide range of metal materials and alloys - High price - Low resolution - low surface finishing

Steel, AL, alloys, Ti,

14. Selective

Laser Melting

New 1 week

Metal powder

+ Resistant metal parts + Insets and tooling for other processes + Wide range of metal materials and alloys + price comparable to laser sintering + high investment costs + only industrial machines

Steel, Al, TI, nickel basis,

….

From Al: 40€ Up to

Ti: 200€

Switch 1 day

Minor change

1-2 days

Post processing for accuracy for

industrial parts, surface finishing,

sand blasting, support

removement


4.2 Review portfolio of Conventional Manufacturing techniques

To summarize the information given by the iBUS consortium regarding conventional manufacturing some issues have to be highlighted and discussed:

None of the conventional manufacturing techniques available in the iBUS consortium have been rated as capable for mass customisation. Solely “Milling” and “CNC Milling” may be rated as partially usable. Mainly this is reasonable by the design change time of these techniques that don’t allow too many changes as this would result in long non-operating time and therefore in a low efficiency. From an objective perspective “Turning” does not differ too much from “Milling” so that this technique might be as capable for mass customisation as “Milling” at least when talking about manual machine. But for sure “Turning” in total is able to produce parts with different degrees of freedom in design. The usability of these techniques is strongly dependent on the down laying management of design data in conjunction with the CNC programming of the machine. Subject to condition that a more or less automatic transfer of digital design data into manufacturing commands is used, an economically efficient mass customization may be possible. Therefore, these may be suitable for manufacturing of minor and parametric customized designs. For a parametric customization it might be easy to fit a CNC code to these parametric values and thereby enable a fully automatic mass customization. Even if the design change time is very high for most of the conventional manufacturing techniques in particular for forming technologies, they are usable for one specific approach: hybrid manufacturing in terms of combining components produced in a high batch size with customised components in a low or even single batch size. For example, in the toy-area one can think about dolls that are divided in a mass production body and customised heads. The table shows low hourly rates for conventional techniques so that it would be very likely to develop concepts to consider those techniques in the iBUS business model.

4.3 Review portfolio of Additive Manufacturing techniques

To summarize the information given by the iBUS consortium regarding additive manufacturing some issues have to be highlighted and discussed:

As anticipated before, the additive manufacturing techniques are rated highly different compared to the conventional manufacturing techniques. These new technologies are all rated as highly suitable for mass customization. While there are still some differences and uncertainties for manufacturing completely new designs, all techniques are cabable of very fast design changes. For some techniques the specific data preparation in terms of building parameters like orientation, position and temperature control has to be adjusted what causes design change times of several days. Though, after determining these critical designs it is very easy to change designs / products built one after another and to repeat the built of this entity.

For iBUS a broad range of different techniques and machines are available, so that no lacks for starting iBUS Platform can be recognized by now.


4.4 Review portfolio of Rapid Tooling techniques

To summarize the information given by the iBUS consortium regarding additive manufacturing some issues have to be highlighted and discussed:

The results of the questionnaire answered by the iBUS consortium members shows that all of the subtractive and additive techniques can be or even are used to produce tools and/or moulds. The processable materials indicate the main difference in the applicability of these techniques. While subtractive techniques are able to process metals and plastics the additive techniques are limited to specific materials processable. Thus the techniques are limited in its application. Additive manufacturing offers a higher freedom in design and at least for complex geometries a benefit in time but comes along with barriers in terms of surface quality. Subtracive machining offers high potentials for surface quality and accuracy but is limited in complexity and speed.

If the generation of the tool or mould can be rated as “rapid” is depending on the geometry of the end product and acceptable tolerances and envisaged batch size that should be achieved in forming techniques using the mould: The more complex the geometry the higher the effort for producing the tool or mould. Further it depends on accepted tolerances if for example a mould is usable directly after being produced in Selective Laser Melting or if post processing is needed to enhance the surface quality. For small batch sizes in blow or injections molding plastic inserts can be used. For high batch sizes metal moulds are more promising to achieve a constant part quality.

The questionnaire indicated the usable techniques during the iBUS project. The specific technique is very much depending on the part selected for the projects use cases as there are multiple factors influencing a decision: Material of end product, batch size, geometry and targeted accuracy.


4.5 Decision support table assessing manufacturing techniques

The following table summarises all given information very compressed so that it can be used for decision support for example for the selection of suitable part candidates to be considered during iBUS project:

Requirement Milling Turning Injection Moulding

Laser Sintering

Fused Layer

Modelling

Sho

rt c

han

ge o

ver

tim

e

(har

dw

are

)

Switch of design 1 1 3 nm 2 em

1 1

Preparation of next shot

3 3 1 2 2

Flexible material change

1 1 3 3 1

Automated generation of machine code

2 2 3 1 1

1 = good (less effort) 2 = moderate 3 = bad (high effort) nm = including new mould em = reuse existing mould


5. References

[ABSB15] Amit Bandyopadhyay, Susmita Bose (2015): “Additive Manufacturing”; CRC Press; USA.

[AESS15] A. K. Haghi, Eduardo A. Castro, Sabu Thomas, P. M. Sivakumar, Andrew G. Mercader (2015): “Materials Science of Polymers: Plastics, Rubber, Blends and Composites”; CRC Press; USA.

[CHAH00] Charles A. Harper (2000): “Modern Plastics Handbook” ; McGRAW-HILL; USA.

[CHAH06] Harper, Charles A. (2006): “Handbook of Plastics Technologies: The Complete Guide to Properties and Performance”; McGRAW-HILL; USA.

[DAKOS93] Koshal, Dalbir. (1993): “Manufacturing Engineer's Reference Book”; Elsevier; Germany.

[EAAS12] Eleonora Atzeni, Alessandro Salmi (2012): “Economics of additive manufacturing for end-usable metal parts”; Springer; Germany.

[GAFB87] Gary F. Benedict (1987): “Nontraditional Manufacturing Processes” ; CRC Press; USA.

[GUYA15] Guohui Yang (2015): “Advances in Future Manufacturing Engineering: Proceedings of the 2014 International Conference on Future Manufacturing Engineering”; CRC Press; USA.

[GWRB09] Dr. Ian Gibson, Dr. David W. Rosen, Dr. Brent Stucker (2009): “Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing”; Springer; Germany.

[PHEM96] Mitchell, Philip E. (1996): “Tool & Manufacturing Engineers Handbook: Plastic Part Manufacturing”; 4th Edition; Society of Manufacturing; USA.

[PILL04] Piller, F. (2004) “Mass Customization: Reflections on the State of the Concept”, Journal of Flexible Manufacturing Systems, Springer Science + Business Media Inc.


[PILL15] Frank Piller, The 2015 World Conference on Mass Customization, Personalization and Co-creation, MCPC 2015, Montreal, oct. 2015

[SRSU2015] T.S. Srivatsan, T.S. Sudarshan (2015): “Additive Manufacturing: Innovations, Advances, and Applications”; CRC Press; USA.

[TSJI01] Tseng, M.M. and Jiao, J. (2001) “Mass Customization,” Handbook of Industrial Engineering, Gaviel Salvendy (Ed.), 3rd edition, Wiley, New York

[YEMA11] Helmi A. Youssef, Hassan A. El-Hofy, Mahmoud H. Ahmed (2011): “Manufacturing Technology: Materials, Processes, and Equipment”; CRC Press; USA.

[VOX16o] http://www.voxeljet.de/fileadmin/Voxeljet/Systems/Materialdatenblatt.pdf

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ibus -iBUS Evaluation Report Rapid Manufacturing of ...h2020ibus.eu/.../09/D4-1-iBUS...customised-designs-Rev-2.0-Final.pdf · In a co-design system, the solution space, ... the elicitation