Transcript Document

Design / Rekabentuk
What is a design……?????
Webster’s dictionary
To design is to fashion after a plan
The 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.
Design / Rekabentuk
Who involve….
Engineer
Figure out ways to provide things that are needed or
wanted
Basic needed
cheaper, easier to use, comfort,
reliable, high quality
Can 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 Process
The design process
Consist of the following steps
Recognition of the need
Definition of a problem
Gathering information
Conceptualization
Evaluation
Communication of the design
Design Process
Recognition of need
Input from operating or service or marketing
representative
Usually 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 problem
Involve analyzing and clearly stating the problem
Critical 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 look
Define 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 / Rekabentuk
Gathering of information
To identify the needed pieces of information and find or
developed that information
The 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 Process
Conceptual design
The 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 design
This stage will evaluate the two or three
conceptual solution or scheme selected in greater
detail.
Make final choice
The selection is done with considerable
feedback to the conceptual design activity
The output of this stage should be rough
drawing
Design Process
Detail design
Consider 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 activities
Can be classified into analytical, creative and execution
types.
Analytical activities
Establishment of proposed action and collection of
the data
Creative activities
The 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 selection
It 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 details
Final stage, final design is made based on the data of
actual material to be used
Design Process
Factors in material selection
Property profile
i. 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 profile
i. 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 considerations
1. 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 implication
Initial cost during application
Example :
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 fiberreinforced composite.
Carbon fiber frame now weight only 1.14 kg!
Design Process
ii. Processing and fabricability
Related to the ability to form or shape the material.
Casting
very intricate shapes
Deformation
ductile metals and
thermoplastic materials
Ceramic
materials usually shapes by
slower sintering
Composite spry forming and lay-up technique.
Fabricability embraces the joining processes
( welding, soldering, brazing ), forming and
machining process.
Design Process
Manufacturing concerns
1. Has the design addressed the requirements that will
facilitate ease of manufacture ?
2. How many of the component are to be produces ? At
what rate
3. 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 availability
If 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 profile
i. 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
OSHA
Toxic chemical or solvents used in cleaning and processing, cannot be
disposed with the regular sewage.