Engineering Design Notes
Engineering Design is a decision making process (often iterative or recursive) in which the
sciences are applied to modify/create something to meet predefined objectives (specifications).
Basic stages of the design process include establishment of objectives and criteria, analysis,
synthesis, definition of actual manufacturing techniques and routes as well as the modes of
usage, maintenance and disposal.
Design is problem solving. One possible route to follow in the design process is for example:
1. Establish the need (realise there is a problem to be solved)
2. Plan how to solve the problem (consult others, e.g. by means of brain-storming)
3. Understand the problem by developing requirements and uncovering existing solutions to
4. Generate alternative solutions
5. Evaluate the alternatives by comparing them to the design requirements and to each other
6. Decide on acceptable solutions and produce the conceptual design
7. Communicate the results, e.g. produce layout drawings, detailed design drawings and
8. Produce the final technical documentation including the time schedule and costing
9. Manufacture and test prototype
10. Full scale manufacture
11. Sale and follow up the customer’s satisfaction.
The following figures summarise some concepts related to design process:
Some aspects of the design approach can be outlined as follows:
Sustainability: Ideally design should anticipate (minimise) deterioration (e.g. abrasion,
corrosion) of each component to prevent the need for any further maintenance, by design-out and
• Testing workplace isolation procedures, including safety permits and the isolation tagging
system, are essential in a hazardous area and must be incorporated into the planning for testing
the design prototypes.
• Standard job procedures, including methods, spares used, tools, and safety procedures, should
• All prototype tests should be preceded by a discussion of safety procedures and requirements.
Proposed modifications should also have been through a hazard and operability check before
they are actioned.
• All contract labour engaged in the design should be subject to job quality checks and should go
through a safety induction programme appropriate to the specific equipment.
• All spare parts, whether new or reconditioned, should be subjected to a quality assurance
Useful strategic questions to be asked during the design process:
WHAT: Why is it done at all? / Why is it necessary? / Why not eliminate it?
WHERE: Why is it done there? / Why not change the place? / Why not change the sequence? /
Why not combine?
WHO: Why does the person do it? / Why not change the person? / Why not change the
sequence? / Why not combine?
HOW: Why is it done this way? / Why not do it a different way? / Why not improve it? / Why
not make it easier?
Components of the final product quality that should be aimed at are presented below:
Since any design is an experiment, it is sensible to use the design technique termed “probabilistic
design”, especially if we our design project involves consumption of significant resources.
(See also: http://www.grassmannalgebra.info/probabilisticdesign ).