Assembly Process Design and Virtual Validation€¢ Using standard process times to design manual and semi-automated assembly cells • Analysing 3D models of the assembly cells using

© 2016 High Value Manufacturing Catapult. All rights reserved.

The Proving Factory is a £22m manufacturing initiative designed to

strengthen the UK’s automotive supply chain. The project, established

with funding from the private sector and the government’s Advanced

Manufacturing Supply Chain Initiative (AMSCI), was created to provide

a route from prototype to production for advanced low carbon

technologies.

A key objective was to establish a flexible UK manufacturing and

assembly facility capable of volume production (200,000 units/annum)

for 6 high speed, rotating powertrain technologies, thereby de-risking

future OEM investment.

The role of the Manufacturing Technology Centre (MTC) within the

project was to support Productiv in the industrialisation of the Proving

Factory assembly facility concept through:

• Applying a Design For Assembly methodology to optimise the

technologies for mass production

• Simulating manufacturing systems to suggest an optimal strategy for

production

• Using standard process times to design manual and semi-automated

assembly cells

• Analysing 3D models of the assembly cells using an immersive

Virtual Reality suite and ergonomics software

• Physically validating processes through manual assembly test builds

and automated pick-and-place robot trials

Taking Low Carbon Technologies from Prototype to Production Using Virtual and Physical Assembly Validation

Assembly Process Design and Virtual Validation

March 2016

MTC Case Study 30876-002


The initial six technologies selected for the Proving Factory entered the

project at prototype level. Their designs were focused on demonstrating

the viability of each technology through small batch production. For this

reason, many components were machined from billet and assembly

processes based on workshop practices.

To enable mass production of the technologies, the MTC applied a

Design For Assembly (DFA) methodology with three key principles:

1. Functional Analysis – facilitates part count reduction by the

evaluation of each component in the design in order to determine

whether it is essential for the performance of the product.

2. Feeding Analysis - evaluates the suitability of a component for

manual handling to the point of assembly

3. Fitting Analysis - is used to highlight problems and inefficient

operations associated with the build sequence and component

interfaces, and to identify the tooling requirements of the design

(Figure 1.)

The assembly hierarchy for each product was mapped and each

process within it analysed. Applying these techniques raised potential

assembly issues early and resulted in a significant reduction in part

count across the technologies. It also highlighted opportunities to

commonise commodity items such as fasteners, seals and sensors.

March 2016

Design For Assembly Analysis

Figure 1. Checking tool access

using 3D CAD



Assembly Strategy Review

The specification for the Proving Factory assembly facility detailed a

flexible facility that could produce up to 20,000 units per annum for ten

different technologies. This shared factory concept raised various

questions regarding the best way to design a factory that can deal with

large variation in product whilst maximising commonality and minimising

investment costs.

The MTC researched various possible strategies from several industries

and highlighted two potential solutions:

• A single, flexible, mixed-model assembly line capable of assembling

any product (Figure 2.)

• Cellular manufacture, with each product assembled in a dedicated cell

Using modelling and simulation techniques, the MTC then tested the

performance of each system and used the results to build a comparison

matrix, which also considered factors such as training, logistics and

reliability. The matrix showed cellular manufacture to be the optimum

strategy, with large investment resources such as clean-rooms shared

between cells.

March 2016

Figure 2. Visualisation of a single,

flexible production line with sub-

assembly stations



Assembly Process and Cell Design

With a cellular manufacturing strategy signed off by the consortium, the MTC’s

next task was to design suitable cells for assembling the technologies. This

was achieved by creating a spreadsheet tool for mapping standard process

times to each component in a given Bill Of Material. Within the tool, these

processes were then divided amongst several operators to create a balanced

assembly line capable of producing each product at the required rate.

The large majority of assembly processes were designed to be carried out by

manual operators, dictated by the production volumes and degree of flexibility

required. However, Process Failure Mode and Effect Analysis (PFMEA)

highlighted certain procedures as high risk, for example health and safety

issues with high strength magnets and also the potential for operators to

damage delicate foil components. To mitigate those high risk processes a

degree of automation was required. The MTC researched and compared

solutions including flexible robotics, dedicated machinery and semi-automated

fixtures, to compare factors such as investment and payback, commissioning

and training required as well as quality. Flexible robotics emerged as the

optimum solution, largely due to the ease and speed at which the systems can

be reconfigured for new tasks.

The MTC also conducted a state of the art review into manual assembly work

stations and equipment. Through this research, it was found that modular

extruded aluminium systems were well suited to the Proving Factory assembly

processes. Using software containing a library of standard profiles and

connectors, production workstations can be quickly built and configured for a

given application (Figure 3).

0

50

100

150

200

250

300

350

Tim

e (

s)

Figure 3. Designing manual

assembly cells using standard

profiles and connectors

March 2016



Human Factors Assessment of

Assembly Processes

The use of software to simulate real world manufacturing processes is

becoming increasingly popular across various industries. It has been

proven to reduce product development time and cost by tackling

production problems early in the design cycle. The information provided

by modelling and simulation allows for better decisions on issues such as

investment in equipment, staff and facilities.

Virtual Manufacturing software was used by the MTC to analyse the

Proving Factory assembly processes. Using Computer Aided Design

(CAD) models of components and equipment, a detailed 3D model of the

assembly cells was created. By programming human operator assembly

procedures into ergonomics software, the MTC was able to check the

assembly cells and processes for issues such as repetitive strain and

over-exertion. The software provides a means of carrying out operator

reach and vision tests, to ensure the cell is designed as efficiently as

possible (Figures 4 and 5).

The 3D models were also evaluated in the MTC’s virtual reality suite. This

facility, a connected system of computers, projectors and tracking

equipment, creates an immersive 3D viewing experience in which CAD

models and scan data can be assessed at full scale. Viewing the Proving

Factory assembly cells in this way has highlighted further opportunities to

improve and fine tune the cells and their associated assembly tasks.

Figures 4. and 5. Ergonomics

software showing line of sight and

reach testing

March 2016



Physical Assembly Process Validation

The MTC’s final task was to physically validate Proving Factory assembly

processes. That was achieved in two phases:

• Manual assembly trials in a representative trial assembly cell

• Assembly automation trials using a modular, 3-axis pick and place robot

system

During the manual assembly trials, ‘Time and Motion’ studies were used to

validate previous assumptions of process times. The MTC conducted trials of

Bluetooth controlled fastening tools, which can be pre-programmed with assembly

procedures. By monitoring the time taken to assemble each fastener, the software

was able to identify operator error and lock the tool, clearly flagging quality issues.

For the assembly automation trials, the MTC used 3D printing to manufacture

robot end effectors, mock components and fixtures (Figure. 6). The flexibility and

speed of this process proved to be very useful, allowing each design iteration to

be quickly tested and improved. The modular Cartesian robot system, built from

linear servo drives, was well suited to the size of the components in question and

carried out the required processes with good repeatability.

To conclude, the Proving Factory project provided the MTC with an excellent

opportunity to apply a range of engineering tools to optimise both products and

processes. By considering production issues early in the development cycle, it

was possible to make changes before committed costs escalated. The MTC is

now applying these techniques across various sectors to bring new products to

market, in an efficient and cost effective manner.

March 2016

Figure 6. 3D Printed component

fixture


Documents

Assembly Process Design and Virtual Validation€¢ Using standard process times to design manual and semi-automated assembly cells • Analysing 3D models of the assembly cells using