Understand the limitations of design.
1.9 Summary
21 You are responsible for the impact of your products on others. humility in the face of nature. Treat nature as a model and mentor, not as an inconvenience to be evaded or controlled.8. Seek constant improvement by the sharing of knowledge.
Encourage di- rect and open communication between colleagues, patrons, manufacturers, and users to link long-term sustainable considerations with ethical responsi- bility, and reestablish the integral relationship between natural processes and human activity.9. Respect relationships between spirit and matter.
Consider all aspects of human settlement including community, dwelling, industry, and trade in terms of existing and evolving connections between spiritual and material consciousness. We will work to respect these principles in the chapters that follow. We intro- duced the concept of “lean” earlier in this chapter as the effort to reduce waste Principle 5. We will revisit this and the other principles throughout the book. In Chap. 11, we will specifically revisit DFS as part of Design for the Environ- ment. In Chap. 12, we focus on product retirement. Many products are retired to landfills, but in keeping with the first three principles, and focusing on the fifth principle, it is best to design products that can be reused and recycled. 1.9 SUMMARY The design process is the organization and management of people and the infor- mation they develop in the evolution of a product. ■ The success of the design process can be measured in the cost of the design effort, the cost of the final product, the quality of the final product, and the time needed to develop the product. ■ Cost is committed early in the design process, so it is important to pay par- ticular attention to early phases. ■ The process described in this book integrates all the stakeholders from the beginning of the design process and emphasizes both the design of the product and concern for all processes—the design process, the manufacturing process, the assembly process, and the distribution process. ■ All products have a life cycle beginning with establishing a need and ending with retirement. Although this book is primarily concerned with plan- ning for the design process, engineering requirements development, concep- tual design, and product design phases, attention to all the other phases is important. PLM systems are designed to support life-cycle information and communication. 22 CHAPTER 1 Why Study the Design Process? ■ The mechanical design process is a problem-solving process that transforms an ill-defined problem into a final product. ■ Design problems have more than one satisfactory solution. ■ Design for Sustainability embodied in the Hannover Principles is becoming an increasingly important part of the design process. 1.10 SOURCES Creveling, C. M., Dave Antis, and Jeffrey Lee Slutsky: Design for Six Sigma in Technology and Product Development, Prentice Hall PTR, 2002. A good book on DFSS. Ginn, D., and E. Varner: The Design for Six Sigma Memory Jogger, GoalQPC, 2004. A quick introduction to DFSS The Hannover Principles, Design for Sustainability . Prepared for EXPO 2000, Hannover, Germany, http:www.mcdonough.comprinciples.pdf Product life-cycle management PLM description based on work at Siemens PLM supplied by Wayne Embry their PLM Functional Architect. http:www.plm.automation.siemens.comen_usproductsteamcenterindex.shtml http:www.johnstark.comepwl4.html PLM listing of over 100 vendors. Ulrich, K. T., and S. A. Pearson: “Assessing the Importance of Design through Product Archaeology,” Management Science, Vol. 44, No. 3, pp. 352–369, March 1998, or “Does Product Design Really Determine 80 of Manufacturing Cost?” working paper 3601–93, Sloan School of Management, MIT, Cambridge, Mass., 1993. In the first edition of The Mechanical Design Process it was stated that design determined 80 of the cost of a product. To confirm or deny that statement, researchers at MIT performed a study of automatic coffeemakers and wrote this paper. The results show that the number is closer to 50 on the average see Fig. 1.3 but can range as high as 75. Womack, James P., and Daniel T. Jones: Lean Thinking: Banish Waste and Create Wealth in Your Corporation, Simon and Schuster, New York, 1996. 1.11 EXERCISES 1.1 Change a problem from one of your engineering science classes into a design problem. Try changing as few words as possible. 1.2 Identify the basic problem-solving actions for a. Selecting a new car b. Finding an item in a grocery store c. Installing a wall-mounted bookshelfd. Placing a piece in a puzzle
1.3 Find examples of products that are very different yet solve exactly the same design
problem. Different brands of automobiles, bikes, CD players, cheese slicers, wine bot- tle openers, and personal computers are examples. For each, list its features, cost, and perceived quality. 1.4 How well do the products in Exercise 1.3 meet the Hannover Principles?1.5 To experience the limitations of the over-the-wall design method try this. With a group
of four to six people, have one person write down the description of some object that isParts
» Mechanical engineering design process
» Introduction Measuring the Design Process with Product
» The History of the Design Process The Life of a Product
» The Many Solutions for Design The Basic Actions of Problem Solving
» Summary Mechanical Design Languages
» Different Types of Mechanical Constraints, Goals, and
» Product Decomposition Summary Introduction
» The Individual Designer: A Model of Human Mental Processes That Occur
» Characteristics of Creators The Structure of Design Teams
» Building Design Team Performance Overview of the Design Process
» Designing Quality into Products Product Discovery
» Choosing a Project Summary Sources Exercises On the Web
» Product, Project, and Decision Risk
» In engineering design, the designer uses three types of knowledge: knowl-
» A design process that results in a quality product can be learned, provided
» Improved material on project planning.
» Insist on rights of humanity and nature to coexist
» Recognize interdependence. On the Web
» Accept responsibility for the consequences of design
» Create safe objects of long-term value.
» Eliminate the concept of waste.
» Rely on natural energy flows.
» Understand the limitations of design.
» Seek constant improvement by the sharing of knowledge.
» Respect relationships between spirit and matter.
» Engineering Changes Patent Applications Design for End of Life Sources Placing a piece in a puzzle
» Decompose a simple system such as a home appliance, bicycle, or toy into its assemblies,
» For the device decomposed, list all the important features of one component.
» Select a fastener from a catalog that meets these requirements:
» Sketch at least five ways to configure two passengers in a new four-wheeled commuter
» You are a designer of diving boards. A simple model of your product is a cantilever beam.
» Find five examples of mature designs. Also, find one mature design that has been recently
» Teams develop decisions by consensus rather than by authority. This leads to
» Beneficial team behaviors. Well-defined decision process.
» Use of sound generationevaluation approach.
» Standardizes, organizes, and controls operations.
» Provides for consistent dissemination of information.
» Encourages improvement. Team nam
» Generate alternatives Team nam
» Identify criteria importance Team nam
» Based on the evaluation results, decide what to do next. This decision will
» “What I want for myself out of this.” Refine criteria.
» Refine evaluation—work to gain consensus and reduce uncertainty.
» Choose an alternative—you’ve made a decision, document it and address
» Develop a list of original design problems that you would like to do at least 3. Choose
» Make a list of features you don’t like about products you use. One way to develop this
» Executive summary: Team Members:
» Gantt chart: All diagrams, figures, and tables should be accurately and clearly labeled
» References: Appendices: All diagrams, figures, and tables should be accurately and clearly labeled
» For the features of the redesign problem Exercise 4.2 develop a plan as in Exercise 5.1.
» Develop a plan for making a breakfast consisting of toast, coffee, a fried egg, and juice. Be
» Developing the specifications or goals for the product
» Finding out how the specifications measure the customers’ desires
» Determining how well the competition meets the goals
» Developing numerical targets to work toward
» The QFD method can be applied to the entire problem and any subprob-
» Both competitors have good lifting position when transferring the passenger
» Both products have poor stability. Clearly, this is a market opportunity.
» The Colub is easy to move and Delton is not, need to determine why and do
» For most of adjustment requirements, neither of the competitors score above 3,
» Each specification should measure at least one customers’ requirement at
» Each specification should be measurable. Every specification should be writ-
» The first specification “seat width relative to frame width” is not clear. What
» Two points about specifications that are in terms of “number of steps”:
» For a design problem Exercise 4.1, develop a house of quality and supporting informa-
» The interface to the jam plate. Energy flows between the trigger and the jam
» Articulate the conflicting positions or functions. Identify the needs forcing the two positions.
» Articulate the conflicting positions
» Identify the issue, the objective of the needs
» Articulate injections that can relieve the conflict while meeting the objective.
» Many of the problems that engineers face contain elements that have already
» There are predictable patterns of technological change that can be applied to
» Increase degree of an object’s segmentation
» Arrange objects so they can go into action without time loss
» Stating the overall function.
» Decomposing the overall function into subfunctions. If assumptions are needed to
» Identifying all the objects nouns used and defending their inclusion in the functional
» For the redesign problem Exercise 4.2, apply items a–c from Exercise 7.1 and also study
» Which subfunctions must remain unchanged during redesign?
» Which subfunctions if any must be changed to meet new requirements?
» Which subfunctions may cease to exist?
» For the functional decomposition developed in Exercise 7.1,
» A perpetual motion machine. In recent times the patent office has refused to consider
» Use brainstorming to develop at least 25 ideas for
» A way to fasten together loose sheets of paper.
» A device to keep water off a mountain-bike rider.
» A way to convert human energy to power a boat.
» A method to teach the design process.
» Use brainwriting to develop at least 25 ideas for
» A device to leap tall buildings in a single bound.
» Are the critical parameters identified?
» Are the safe operating latitude and sensitivity of the parameters known?
» Have the failure modes been identified?
» Does hardware exist that demonstrates positive answers to the preceding four
» Is the technology controllable throughout the product’s life cycle?
» The source of the component.
» Wheel and chain must clear frame for all deflections. Wheel should move straight up and down.
» Your body while holding a 5-kg weight straight out in front of you with your
» Maximum acceleration on a standard street
» Maximum acceleration on a 5-cm standard pothole
» Identify the critical parameters and interfaces for evaluation.
» Develop a P-diagram for each.
» Choose whether to build physical models for testing or run an analytical experiment
» Perform the experiments or analysis and develop the most robust product.
» For the redesign problem Exercise 4.2, repeat the steps in Exercise 10.1.
» You have just designed a tennis-ball serving machine. You take it out to the court, turn it
» Does your machine have an accuracy or a variation problem?
» Itemize some of the potential causes of each type of error. Consider the types of
» A new, spring-powered can opener
» A diving board for your new swimming pool
» An art nouveau shelf bracket
» From what material is the component to be machined?
» The overall dimensions are 9.46 cm 3.72 in. by 4.52 cm 77 in. in the
» The wall thickness is 3.2 mm 0.125 in..
» The number of components to be manufactured is 1 million.
» The labor hourly rate is 35.
» Find the Theoretical Minimum Number of Components. Examine each
» hr R Mechanical engineering design process
» For the product developed in response to the design problem begun in Exercise 4.1,
» For the redesign problem begun in Exercise 4.2, estimate the changes in selling price
» Estimate the manufacturing cost for a plastic injection-molded component:
» Compare the costs for manufacturing volumes of 100, 1000, 10,000, and 100,000.
» Compare the cost for a change in tolerance.
» Why does changing the material have virtually no effect on cost at low plastic
» Perform a design-for-assembly evaluation for one of these devices. Based on the results
» A simple toy fewer than 10 parts
» Read as many similar instruction manuals as you can. Many companies post
» Organize instructions into sections to make it easy to find answers. Do not
» Recruit members of the user community not familiar with the product to test
» Know your goals and your vendor’s goals. Building a strong vendor relation-
» Involve vendors early. When dealing with vendors, you cannot afford delays
» Establish relationships. It is important to have vendor partners who under-
» Communicate. Put everything in writing—responsibilities, expected sales
» Stay professional. Things go wrong in life. When they go wrong in a relation-
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