Concurrent Engineering Design

The production process executes the final results of the design process to produce a product or system. In the pas\. the creative design process was separated from the production process. With the advent of computer modeling. this separation is no longer necessary. and the modern engineering design approach brings both proc'CSses together.

Concurrent engineering is a nonlinear team approach to design that brings together the input. processes. and output elements necessary to produce a product. The people and processes are brought together at the very beginning. which is not normally done in the linear approach. nte team consists of design and production engineers. technicians. marketing and finance personnel. planners. and managers. who work together [0 solve a problem and produce a product.

Many companies are finding that concurrent engineering pmcticcs result in a belter. higher-quality product. morc satisfied customers. fewer manufacturing problems. and a shorter cycle time between design initiation ,md final production.

Figures 2.7 and 2.8 represent the concurrent approach to engineering design. based on 3-D modeling. The three intersecting circles represent the concurrent nature of this design approach. For example. in the ideation phase. design engineers interact with service technicians to ensure that the product willlJe easily serviceable by theconsumer or technician. This type of interaction results in a better prodllct for the consumer. The three intersecting circles also represent the three activities that are a major part of the conCllrrent engineering design process: ideation. refinement. and implementation. These three activities are further divided into smaller segments, as shown by the items surrounding the three circles.

Design for manufacturabiJity (DFM) and design for assembly (OFA) practices developed out of concurrent

engineering as an elTon to capture manufacturing and assembly knowledge up front in the imitial design

process. This allowed engineering and manufacturing professionals 10 speak a common language that results in an optimilcd product design. OFM and OFA cvcntually cxpanded to include other practices. such as design for serviceability and design for reliability. This led to the realization that it is important to include others in the design process. such as marketing, sales. field service, finance, purchasing. and quality control.

The center area in Figure 2.8 represenL~ the 3-D computer model and rellects the central importance of 3-D

modeling and graphics knowledge in engineering design and production. With the use of a modeling approach. everyone on the team can have access to the current design through a computer terminal. This data sharing is critically important to the success of the design process.

The Engineering Design Process

Bertoline--Wiebe--Miller:

Fundamentals of Graphics

Communication,3/e

The McGraw-Hill

Companies,2001

Read more........

Design Ability

What Designers Say The wish to design things is inherent in human beings, and design is not something that has always been regarded as needing special abilities. It is only with the emergence and growth of industrial societies that the ability to design has become regarded as a specialised talent. Although there is so much design activity going on in the world, the ways in which people design are actually rather poorly understood. It has been thought that perhaps many people possess design ability to some degree, but that only a few people have a particular design 'talent'. However, there is now a growing body of knowledge about the nature of designing, about design ability and how to develop it, and about the design process and how to improve it. When designers are asked to discuss their abilities, and to explain how they work, a few common themes emerge. One theme is the importance of creativity and intuition in design, even in engineering design. For example, the architect and engineering designer Jack Howe has said: I believe in intuition. I think that's the difference between a designer and an engineer... I make a distinction between engineers and engineering designers... An engineering designer is just as creative as any other sort of designer. Some rather similar comments have been made by the industrial designer Richard Stevens: A lot of engineering design is intuitive, based on subjective thinking. But an engineer is unhappy doing this. An engineer wants to test; test and measure. He's been brought up this way and he's unhappy if he can't prove something. Whereas an industrial designer.., is entirely happy making judgements which are intuitive. Engineering Design Methods Strategies for Product Design THIRD EDITION Nigel Cross The Open University, Mi/ton Keynes, UK JOHN WILEY & SONS, LTD Chichester- New York. Weinheim • Brisbane. Singapore. Toronto

Computer-Aided Design and Manufacture of Injection Forging

The design activity is responsible not only for the performance and appearance of the product but also for the cost of the component. Design, therefore, cannot be an isolated activity but must address all available manufacturing routes, with a view to optimizing the quality and cost of the component. With reference to nett-forming, the design exercise is conducted not only to specify the component-form but also to address all manufacturing constraints—machine, material, tooling, and processing conditions. Computer-aided “design for manufacture” is currently the main form of implementing of the “concurrent engineering.” To enable this, CAD/CAM is popularly used as a design approach. Using CAD/CAM approaches, simultaneous design would be effected efficiently by supporting the designer with information on all possible resources required for the design and manufacture of components. Some CAD/CAM systems [42] have demonstrated the potential for the development into decision-support systems for component/tool design. Computer-aided design and manufacture for nett-forming by injection forging is being developed as an aspect of research associated with the development of a decision-support system [64]. Methodology In order to develop a decision-support system for component/tool design using a CAD/CAM approach, several design/evaluation methods have been developed [58, 60, 64–68]. These are described briefly in the following texts. Geometric Modeling The popular strategy used for the development of the design-support systems for forging was to evolve a 2D-CAD system for component and tool design. The system was linked to a knowledge-based system to enable the evaluation of manufacturability. Subsequent to the evaluation of the geometry, the component was transferred to a CAD software to enable detailed design. This approach required the design to operate in several software environments. An integrated system, supported by solid modeling, would enable design and assessment of a component more efficiently. A solid modeling-approach—principal feature modeling—was used to enable component-design for forging within a solid modeling environment [65, 66]; the approach enables integration of currently available 2D-based knowledge-based systems. Design for manufacture requires that the component form is specified in a modular form in order to enable the evaluation of the design. The component may be defined as a combination of primitive forms as is the case in “design by features;” alternatively, the primitive forms which constitute the component may be extracted and identified automatically. Unfortunately, both these approaches are currently at a stage of refinement which only allows their applications to a limited range of component forms. Principal feature modeling [67] combines the strategies of both “design by feature” and “feature recognition” to enable efficient modeling and feature manipulation; the approach was proven to be particularly efficient for the modeling of forging/machining components [65]. Designing is attended to with reference to a prescribed set of performance requirements rather than to prescribed form features. The principal features, which represent the principal geometric profiles of a component, may be defined by the designer using arbitrary geometry—a group of curves on a plane or a curved surface. The principal features which have been generated are linked, exclusively, to a set of prescribed attributes which are catalogued in a database. COMPUTER-AIDED DESIGN, ENGINEERING, AND MANUFACTURING Systems Techniques And Applications VOLUME V I Editor CORNELIUS LEONDES Boca Raton London New York Washington, D.C. CRC Press MANUFACTURING SYSTEMS PROCESSE.

Roughness and waviness

A trace across a surface provides a profile of that surface which will  contain short and long wavelengths (see Figure 4.11). In order for a surface to be correctly inspected, the short and long wavelength  components need to be separated so they can be individually analysed. The long waves are to do with dimensions and the short waves are to do with the SE Both can be relevant to function but in different ways. Consider the block in Figure 6.1. This has been produced on a shaping machine. The block surface undulates in a variety of ways. There is a basic roughness, created by the tool feed marks, which is superimposed on the general plane of the surface.

Thus, one can identify two different wavelengths, one of a small scale and one of a large scale. These are referred to as the roughness and waviness components.

Roughness and waviness have different influences on functional performance. A good example illustrating the differences concerns automotive bodies. Considering the small-scale amplitudes and wavelengths called 'roughness', it is the roughness, not waviness, which influences friction, lubrication, wear and galling, etc. The

next scale up from roughness is 'waviness' and it is known that the visual appearance of painted car bodies correlates more with waviness than roughness. The reason for this is the paint depth is about 100um and it has a significant filtering effect on roughness but not waviness.

Engineering Drawing for Manufacture

by Brian Griffiths

Publisher: Elsevier Science & Technology Books

Read more........