Product Generation
· Products must be developed from concepts through concurrent development of form, material, and production methods. This process is driven by the functional decomposition discussed in Chap. 7.
· Form is bound by the geometric constraints and defined by the configuration of connected components.
· The development of most components and assemblies starts at their interfaces, or connections, since for the most part function occurs at the interfaces between components.
· Product development is an iterative loop that requires the development of new concepts, the decomposition of the product into subassemblies and components, the refinement of the product toward a final configuration, and the patching of features to help find a good product design
Concept Evaluation
· The feasibility of a concept is based on the design engineer's knowledge. Often it is necessary to augment this knowledge with the development of simple models.
· In order for a technology to be used in a product, it must be ready. Six measures of technology readiness can be applied.
· A go/no-go screening based on customers' requirements helps filter the concepts.
· The decision-matrix method provides means of comparing and evaluating concepts. The comparison is between each concept and a datum relative to the customers' requirements. The matrix gives insight into strong and weak areas of the concepts. The decision-matrix method can be used for subsystems of the original problem.
· The advanced decision matrix method leads to robust decisions by including the effects of uncertainty, incompleteness, and evolution in the decision-making process.
· Belief maps are a simple yet powerful way to evaluate alternatives and work to gain team consensus.
· Product safety implies concern for injury to humans and for damage to the device itself, other equipment, or the environment.
· Safety can be designed into a product, it can be added on, or the hazard can be warned against. The first of these is best.
· A hazard assessment is easy to accomplish and gives good guidance.
Understanding the Problem and the Development of Engineering Specifications
· Understanding the design problem is best accomplished through a technique called quality function deployment (QFD). This method transforms customers' requirements into targets for measurable engineering requirements.
· Important information to be developed at the beginning of the problem includes customers' requirements, competition benchmarks, and engineering specifications complete with measurable benchmarks.
· Time spent completing the QFD is more than recovered later in the design process.
· There are many customers for most design problems.
· Studying the competition during problem understanding gives valuable in-sight into market opportunities and reasonable targets.
Wednesday, January 3, 2007
Product Evaluation for Cost, Manufacture, Assembly, and Other Measures
· Cost estimation is an important part of the product evaluation process.
· Features should be judged on their value—the cost for a function.
· Design for manufacture focuses on the production of components.
· Design for assembly is a method for evaluating the ease of assembly of a product. It is most useful for high-volume products that have molded components. Thirteen guidelines are given for this evaluation technique.
· Functional development gives insight into potential failure modes. The identification of these modes can lead to the design of more reliable and easier-to-maintain products.
· Design for the environment emphasizes concern for energy, pollution, and resource conservation in processing raw materials for products. It also emphasizes concern for recycling, reuse, or disposal of the product after its useful life is over
· Features should be judged on their value—the cost for a function.
· Design for manufacture focuses on the production of components.
· Design for assembly is a method for evaluating the ease of assembly of a product. It is most useful for high-volume products that have molded components. Thirteen guidelines are given for this evaluation technique.
· Functional development gives insight into potential failure modes. The identification of these modes can lead to the design of more reliable and easier-to-maintain products.
· Design for the environment emphasizes concern for energy, pollution, and resource conservation in processing raw materials for products. It also emphasizes concern for recycling, reuse, or disposal of the product after its useful life is over
Product Evaluation for Performance and the Effects of Variation
· Product evaluation should be focused on comparison with the engineering requirements and also on the evolution of the function of the product.
· Products should be refined to the degree that their performance can be represented as numerical values in order to be compared with the engineering requirements.
· P-diagrams are useful for identifying and representing the input signals, control parameters, noises, and output response.
· Physical and analytical models allow for comparison with the engineering requirements.
· Concern must be shown for both the accuracy and the variation of the model.
· Parameters are stochastic, not deterministic. They are subject to three types of noises: the effects of aging, of environment change, and of manufacturing variation.
· Robust design takes noise into account during the determination of the parameters that represent the product. Robust design implies minimizing the variation of the critical parameters.
· Tolerance stacking can be evaluated both by the additive method and by statistical means.
· Both analytical and experiment methods exist for finding the most robust design
· Products should be refined to the degree that their performance can be represented as numerical values in order to be compared with the engineering requirements.
· P-diagrams are useful for identifying and representing the input signals, control parameters, noises, and output response.
· Physical and analytical models allow for comparison with the engineering requirements.
· Concern must be shown for both the accuracy and the variation of the model.
· Parameters are stochastic, not deterministic. They are subject to three types of noises: the effects of aging, of environment change, and of manufacturing variation.
· Robust design takes noise into account during the determination of the parameters that represent the product. Robust design implies minimizing the variation of the critical parameters.
· Tolerance stacking can be evaluated both by the additive method and by statistical means.
· Both analytical and experiment methods exist for finding the most robust design
Designers and Design Teams
· The human mind uses the long-term memory, the short-term memory, and a controller in the internal environment in problem solving.
· Knowledge can be considered composed of chunks of information that are general, domain-specific, or procedural in content.
· The short-term memory is a small (seven chunks, features, or parameters) and fast (0.1 second) processor. Its properties determine how we solve problems. We use the external environment to augment the size of the short-term memory.
· The long-term memory is the permanent storage facility in the brain. It is slow to remember, it is fast to recall (sometimes), and it never gets full.
· Creative designers are people of average intelligence; they are visualizers, hard workers, constructive nonconformists with knowledge about the problem domain. Creativity takes hard work and can be aided by a good environment, practice, and design procedures.
· Because of the size and complexity of most products, design work is usually accomplished by teams rather than by individuals.
· Working in teams requires attention to every team member's problem-solving style (including yours)—introverted or extroverted, fact- or possibility-oriented, objective or subjective, decisive or flexible.
· Knowledge can be considered composed of chunks of information that are general, domain-specific, or procedural in content.
· The short-term memory is a small (seven chunks, features, or parameters) and fast (0.1 second) processor. Its properties determine how we solve problems. We use the external environment to augment the size of the short-term memory.
· The long-term memory is the permanent storage facility in the brain. It is slow to remember, it is fast to recall (sometimes), and it never gets full.
· Creative designers are people of average intelligence; they are visualizers, hard workers, constructive nonconformists with knowledge about the problem domain. Creativity takes hard work and can be aided by a good environment, practice, and design procedures.
· Because of the size and complexity of most products, design work is usually accomplished by teams rather than by individuals.
· Working in teams requires attention to every team member's problem-solving style (including yours)—introverted or extroverted, fact- or possibility-oriented, objective or subjective, decisive or flexible.
Describing Mechanical Design Problems and Process
· A product can be divided into functionally oriented operating systems. These are made up of mechanical assemblies, electronic circuits, and computer programs. Mechanical assemblies are built of various components.
· The important form and function aspects of mechanical devices are called features.
· Function and behavior tell what a device does; form describes how it is accomplished.
· Function relates desired behavior.
· One component may play a role in many functions, and a single function may require many different components.
· There are many different types of mechanical design problems: selection, configuration, parametric, original, redesign, routine, and mature.
· Mechanical objects can be described semantically, graphically, analytically, or physically.
· The design process is a continuous constraining of the potential product designs until one final product evolves. This constraining of the design space is made through repeated comparison with the design requirements.
· Mechanical design is the refinement from abstract representations to a final physical artifact.
· The most valuable information is the decisions that are communicated to others.
· The important form and function aspects of mechanical devices are called features.
· Function and behavior tell what a device does; form describes how it is accomplished.
· Function relates desired behavior.
· One component may play a role in many functions, and a single function may require many different components.
· There are many different types of mechanical design problems: selection, configuration, parametric, original, redesign, routine, and mature.
· Mechanical objects can be described semantically, graphically, analytically, or physically.
· The design process is a continuous constraining of the potential product designs until one final product evolves. This constraining of the design space is made through repeated comparison with the design requirements.
· Mechanical design is the refinement from abstract representations to a final physical artifact.
· The most valuable information is the decisions that are communicated to others.
Why Study the Design Process?
The design process is the organization and management of people and the information 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 particular attention to early phases.
· Concurrent engineering 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 planning for the design process, engineering requirements development, conceptual design, and product design phases, attention to all the other phases is important.
· 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.
· In problem solving there are seven actions to be taken: establish need, plan, understand, generate, evaluate, decide, and communicate.
· 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 particular attention to early phases.
· Concurrent engineering 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 planning for the design process, engineering requirements development, conceptual design, and product design phases, attention to all the other phases is important.
· 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.
· In problem solving there are seven actions to be taken: establish need, plan, understand, generate, evaluate, decide, and communicate.
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