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Unit16 Product Design and CAD/CAM Unit Introduction Product Design and CAD CAD System Hardware CAM, CAD/CAM, and CIM
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16.1 Introduction Product design serves an important function in the production system. It helps determine the eventual commercial success of a product; it determines how the production system should be created, and exactly what equipment should be bought; and it determines how easily, and how cheaply, the product can be manufactured.
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16.3 Product Design and CAD Computer-Aided Design (CAD) is the use of computer systems (or workstations) to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing.
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16.3 Product Design and CAD Computer-Aided Manufacturing (CAM) is the use of software to control machine tools and related ones in the manufacturing of workpieces
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16.3 Product Design and CAD Computer Integrated Manufacturing (CIM) is the manufacturing approach of using computers to control the entire production process
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16.3.1 The Design Process Recognition of need—this involves the realisation that a problem or need exists that may be solved by design. Problem definition—this involves a thorough specification of the item to be designed. Synthesis—closely related with the following step, analysis, synthesis refers to the bundling of information that occurs after problem definition, and concurrently during analysis, and after re-analysis.
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16.3.1 The Design Process Analysis and optimization—closely related to the previous step, analysis is concerned with the investigation of design specification information, and the optimization of this information, as well as a synthesis of new information, as required. Evaluation—involves measuring the design against the specifications established in the problem definition phase. Presentation—this is the final phase, where the design is documented by means of drawings, material specifications, assembly lists, and so on. Documentation means that the design database is created.
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16.3.2 Applications of Computers in Design Computer-aided design (CAD) is any design activity that involves the effective use of a computer to create, modify, analyze, or document an engineering design. Increased design productivity Increased available geometric forms in the design Improved quality of the design Improved design documentation Creation of a manufacturing database Design standardization The output of the CAD system is stored in a product data management (PDM) system. A PDM system consists of computer software that provides links between users and a central database, where engineering design data and related documentation is stored.
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16.3.2 Applications of Computers in Design Geometric modelling creates a mathematical description of the geometry of an object, so that the subsequent description can be displayed as an image on CAD systems, which may be manipulated by the operator. There are two types of geometric models used in CAD; these are: Two-dimensional modelling—dating from the late 1960s and early 1970s, when the first CAD systems began to appear, this is primarily used for design problems, such as flat objects and layouts of buildings. Three-dimensional modelling—emerging after two-dimensional modelling, these systems are capable of modelling an object in three dimensions according to user instructions, which has been found useful for conceptualising the object, as the three- dimensional model can be displayed in various views and from different angles.
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16.3.2 Applications of Computers in Design Geometric models in CAD can also be classified as wire-frame models, or solid models.
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16.3.2.1 Engineering Analysis Computer-aided engineering (CAE) software packages are used to perform complex engineering calculations by computer. Mass properties analysis Interference checking Tolerance analysis Finite element analysis Kinematic and dynamic analysis Discrete-event simulation
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16.4 CAD System Hardware The hardware used in a CAD system includes: design workstations; digital computers; output devices, such as plotters and printers; and various secondary storage devices.
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16.5 CAM, CAD/CAM, and CIM 16.5.1 Computer-Aided Manufacturing Computer-Aided Manufacturing (CAM) is the application of computer technology to the areas of manufacturing planning and control.
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16.5 CAM, CAD/CAM, and CIM Manufacturing control uses CAM applications to manage and control the physical operations of the factory.
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16.5.2 CAD/CAM CAD/CAM is concerned with engineering functions in both design and manufacturing; it denotes an integration of design and manufacturing activities by means of computer systems. Concurrent engineering defines a system whereby the whole life cycle of a product is considered concurrently. CAD/CAM is an example of an application widely used in concurrent engineering.
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16.5.3 Computer-Integrated Manufacturing Computer-integrated manufacturing (CIM) includes all of the engineering functions of CAD/CAM, but it also includes the firm’s business functions that are related to manufacturing.
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16.5.3 Computer-Integrated Manufacturing CIM has a wider scope than CAD/CAM, so that at higher levels CIM subsumes CAD/CAM and adds functions of its own.
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16.5.3 Computer-Integrated Manufacturing CIM adds a series of computerized business systems that account for peripheral elements entering and exiting the manufacturing system, alongside those that emerge from CAD/CAM.
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