Design/Development Overview

1. Design/Development Overview

2. THE ENGINEERING DESIGN PROCESS • Focus herein will be on product design, however much of what is presented is just as applicable to the design of processes • The design process is often combined/confused with product development - it is difficult to distinguish where design ends and development begins • Stages/phases in the design/development process begin with recognition of customer needs/wants through to production (first article)

3. RECOGNITION OF NEEDS/WANTS • The needs/wants are subjective and dependent on the customer (consumer, company, government) • How does one become aware of the needs/wants? - marketing, publications (http://www.fbo.gov which has replaced Commerce Business Daily, industry publications), ongoing customer relationships, ... • Can create the needs/wants? - hula hoop, pet rocks, …

4. DETERMINATION OF DESIGN CONCERNS • Design concerns are defined by the customer and consist of design requirements (needs) and design goals (wants) • The engineer must translate, what is often times, qualitative needs/wants of the customer into quantitative and measurable design requirements and goals • Distinction between design requirements and design goals • design requirements - must be met for the design to be considered a possible solution (yes or no) • design goals - features desirable in the design - the closer the design is to achieving the goals the better the design (better or worse)

5. IN THE DESIGN OF A BICYCLE • Design requirement - strength: The bike must support the weight of the rider (with a reasonable factor of safety) without failing. The rider doesn't care if the bike can support twice that weight. All the rider cares about is that the bike doesn't break when he/she rides it. The rider will not look upon the design which is able to support twice his/her weight with any additional favor. • Design goal - weight: The bike should be lightweight. Given everything else is the same, if one bike weighs 20 lb and another bike weighs 15 lb, the rider will prefer the design which weighs 15 lb

6. CAN A DESIGN CONCERN BE BOTH A REQUIREMENT AND A GOAL? • Although not typical, a design concern may be both a requirement and a goal • a product may have specific regulations governing a design concern (a design requirement), however, for that same design concern the customer may desire the product go beyond the regulation (a design goal) • i.e. automobile crash safety

7. THE BEST SOLUTION • A possible solution to a design problem meets all of the design requirements • The one possible solution which is superior with respect to the design goals is the best solution • There can be many possible solutions to a design problem, but only one of those possible solutions is the best solution • The best solution will be the design of choice (will be the one selected by the customer, will receive the contract award in an industry setting)

9. THE NEXT THREE STEPS IN THE DESIGN PROCESS ARE ITERATIVE AND THE ORDER MAY BE ALTERED • Development of preliminary design concepts • Perform analyses (confirm the design concepts comply with the design requirements and quantify the design concepts with respect to the design goals) • Application of some decision theory/process to determine which design concept is the best solution • in order to be considered as a possible solution, the design concept must comply with all the design requirements, therefore the decision process is applicable only to the design goals • the decision process can take the form of a simple matrix where the performance of each of the design concepts with respect to the design goals is compared

10. The analyses may lead to revision of the design concepts or possibly, some combining of design concepts. If that is the case, then the revised design concepts would need to be analyzed and so on. It may be preferable to do some evaluation (application of a decision process) right after development of the design concepts in order to reduce the amount of detailed analyses necessary. • The design of choice is the one which meets the design requirements and is superior with respect to the design goals

11. PRODUCT DEVELOPMENT PROCESS • Stages of product development include: • product CAD files • design tooling, tooling CAD files, and fabrication • fabrication process definition • quality assurance plan (inspection plan, testing plan) • fabrication of tool proof/process verification unit • inspection • fabrication of qualification test unit • qualification testing • fabrication of first article unit • production • At stages in the product development process, redesign of the product may be necessary • Many stages are done concurrently, rather than sequentially

12. STEPS IN THE DESIGN/DEVELOPMENT PROCESS ARE USUALLY CARRIED OUT IN A TEAM ENVIRONMENT • The team should include representation from various functions including: product engineering, manufacturing engineering, production, quality control, marketing, program management • Responsibilities/contribution to the design/development by each function: • product engineering: product design, CAD, analysis, … • manufacturing engineering: fabrication process, tooling design, CAD, … • production: fabrication of the product • quality control: qualification testing, inspection, acceptance testing, … • marketing: customer insight (greatest awareness of customer desires) • program management: budget, schedule, …