Design / Rekabentuk

What is a design……?????Webster’s dictionary

To design is to fashion after a planThe essential fact..

To create something that has never been To design is to imagine, specify and create things that don’t exist, usually with the aim of bringing them into the world.

Who involve….Engineer

Figure out ways to provide things that are needed or wantedBasic needed cheaper, easier to use, comfort,

reliable, high qualityCan evaluate conformance of the product to the design requirements. Material engineer provide the expertise in the optimum material selection that will be used to construct or make product.

Design / Rekabentuk

The design processConsist of the following steps

Recognition of the needDefinition of a problemGathering informationConceptualizationEvaluationCommunication of the design

Design Process

Recognition of needInput from operating or service or marketing representativeUsually arise from dissatisfaction with the existing situation

May be to reduces cost, increase reliability or performance or just change because the public has become bored with the product.

Design Process

Definition of problemInvolve analyzing and clearly stating the problemCritical step the true prob. is not always what it seems to be at first glance

Require small part of the total time to create formal design

Often over lookDefine problem as broad as possible

Should involve writing down a formal problem statement

Design Process

Which express as specifically as possible what the design intended to accomplish.

Objectives and goals, definition of any special technical terms, constrains on the design, criteria that will be used to evaluate design.

Design Process

Gathering of informationTo identify the needed pieces of information and find or developed that informationThe needed information is different form the find in text book or articles published in journal

The information is often more specific and current and current information. Information can be supply by the supplier, discussion with experts ( corporate with R & D center ) and outside consultants may be helpful.

Design / Rekabentuk

Conceptual designThe objective is to generate possible solution, schemes or methods to solve the problem.To achieve these possible solution, the team should conduct unconstrained discussion to get the member express all possible solution.In this phase, all information and previous knowledge are put together in order that the proper decision can be made.The output should be two or three schemes that have the greatest chance of achieving the desire objective.

Design Process

Embodiment designThis stage will evaluate the two or three conceptual solution or scheme selected in greater detail.

Make final choiceThe selection is done with considerable feedback to the conceptual design activityThe output of this stage should be rough drawing

Design Process

Detail designConsider all the large number of small but important details to make or fabricate the product or component.The quality of work must be good

Otherwise will course a delays, high cost, failure occur.

The output of this activity is a set of very detailed drawing and final specification including tolerance, precision, joining method, finishing…

To produce the component or product.

Design Process

Design activitiesCan be classified into analytical, creative and execution types.Analytical activities

Establishment of proposed action and collection of the data

Creative activitiesThe analysis, synthesis and evaluation and development activities.Engineer expected to do

Design Process

Execution activities.The designer, in conjunction with client and/or company management, must make a decision and communicate it by means of detailed drawing, specification and other method.

Results of these activities are constantly matched with the requirements and constraints.

Design Process

Materials selectionIt is a crucial that the materials selection should be a part in the decision process at each stage of design.Allows the designer to find out early in the process, if there any problem in the availability, cost or processability of material.Choice of material should start at the conceptual stage.

Identify possible materials from very broad class of material.In embodiment stage, we look in greater detailsFinal stage, final design is made based on the data of actual material to be used

Design Process

Factors in material selectionProperty profilei. Mechanical factor

The ability of material to withstand the types of stresses imposed on it.Strength, modulus, the fracture toughness, fatigue strength, creep.

ii. Life of component factors.These factor related to the length of time, the material perform their intended function in the environment to which they are exposed.

Design Process

Corrosion, oxidation, wear resistance and the fatigue or corrosion fatigue life properties in dynamic loading.Performance of material based on these properties is the hardest to predict during design stage.

Processing profilei. Physical factors

Size, shape and weight of material needed and the space available for the component.Size and shape of component might constraint the heat treating of the material.

Design Process

Example :Large size component may not be provided as a whole piece and consideration may have to be given to joining smaller sub-components.

Necessitate to make the sub-component that are transportable.The shape of the sub-component material will dictate whether a casting or wrought product will be required.Influence the performance of material, when stressed in different modes.

Design Process

Geometry considerations1. What is the relative size of the component ?2. How complex is the shape ?Are there any uniform cross section ?

Could the component be divided into several simpler shape that might be easier to manufacture?

3. How many dimensions must be specified ?4. How precise must these dimensions be ? Are all precise ? How

many are restrictive, and which ones ?5. What are the surface finish requirements ? Must all surfaces be

finished ? Which ones do not ?6. How much can a dimension change by wear or corrosion and the

part still function adequately ?

Design Process

Weight of material has implicationInitial cost during applicationExample :

In transport industry, where lightweight structures save energy cost and increase profitability.

At one time, bicycle frame were constructed from welded steel tubing, now have being change to aluminum alloy, titanium alloy, and various fiber-reinforced composite.

Carbon fiber frame now weight only 1.14 kg!

Design Process

ii. Processing and fabricabilityRelated to the ability to form or shape the material.

Casting very intricate shapesDeformation ductile metals and thermoplastic materialsCeramic materials usually shapes by slower sinteringComposite spry forming and lay-up technique.

Fabricability embraces the joining processes ( welding, soldering, brazing ), forming and machining process.

Design Process

Manufacturing concerns1. Has the design addressed the requirements that will

facilitate ease of manufacture ?2. How many of the component are to be produces ? At

what rate3. What is the desire level of quality compared to similar

products on the market ?4. What are the quality control and inspection

requirements ?5. What are the largest and small thickness ?6. Have standard sizes and shapes been specified wherever

possible ?

Design Process

iii. Cost and availabilityIf the materials are readily available, it matter whether orders are made in tonnages or in pounds or grams.

Customer also pays a cost-penalty when orders are nonstandard items requiring special or are nonstocked items, due to very little demand form other customers.Prepare recommend alternatives materials, provided that they are feasible candidates for the specific use.

Design Process

Environmental profilei. Codes, statutory

Codes are sets of technical requirements that are imposed on the material or the component

Usually sets by customer or based from those of technical organization

Statutory related to local, state and federal regulation about the materials and processes used or the disposal of material.

Leaded brasses and steel used for bolt and screws, has banned by the OSHAToxic chemical or solvents used in cleaning and processing, cannot be disposed with the regular sewage.

Design Process