Product Design & CAD
Product Design & CAD
Product Design & CAD
Dr Chong
Procedures & systems used by a firm to manage production & solve the technical and logistic problems (products design, processes planning, materials ordering, work-in-process control, products delivering to customer) Many y of these functions can be automated using g computer p systems computer-aided design (CAD) , computerintegrated manufacturing (CAM)
Any design activity that involves the effective use of the computer to create, modify, analyze, or document an engineering design
Terminology CAD(Computeraideddesign) CAM(Computeraidedmanufacturing) CIM(Computerintegrated d manufacturing) f Explanation Usesthecomputertosupportthedesign engineeringfunction Usesthecomputertosupport manufacturingengineeringactivities Includes l d all llof fCAD/CAM Embracesthebusinessfunctionsofa manufacturingfirm
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Product Design and CAD CAD System Hardware CAM, CAD/CAM, and CIM Quality Function Deployment
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The general process of design is characterized as an iterative process consisting of six phases:
Dr Chong
1. Recognition of need - someone recognizes the need that can be satisfied by a new design 2. Problem definition - specification of the item 3. Synthesis - creation and conceptualization 4. Analysis and optimization - the concept is analyzed and redesigned 5. 5 Evaluation - compare design against original specification 6. Presentation - documenting the design (e.g., drawings)
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To increase the productivity of the designer; To expand the available geometric forms in design wider range of mathematically defined shapes possible; To improve the quality of the design - more engineering analysis possible, consideration of more alternatives
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To improve design documentation - better drawings th with than ith manual ld drafting fti To create a manufacturing database - creation of the design documentation also creates manufacturing data To promote design standardization - use of design rules to limit the number of hole sizes, fasteners, etc.
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3. Geometric modeling CAD system develops a mathematical description of the geometry of an object, called a geometric model 4 Engineering analysis 4. Mass properties, interference checking for assemblies, finite element modeling, kinematic analysis for mechanisms 5. Design evaluation and review Automatic dimensioning, error checking, animation 6. Automated drafting Preparation of engineering drawings quickly
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Wire-frame model
Solid model
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The hardware for a typical CAD system consists of the following components:
1. 1 2. 3. 4.
One or more design workstations orkstations Digital computer Plotters, printers, and other output devices Storage devices
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The interface between the computer and the user in the CAD system
Functions:
1. 2. 3. 4. 5. 5
Communicate with the CPU Continuously generate a graphical image Provide digital descriptions of the image Translate user commands into operating functions Facilitate ac tate interaction te act o bet between ee t the e use user a and dt the e system
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1. Host and terminal Mainframe serves as host for graphics terminals The Th original i i l configuration fi ti i in th the 1970 1970s and d 1980 1980s when h CAD technology was first developing 2. Engineering workstation Stand-alone computer system dedicated to one user Often networked for sharing data and plotters 3. CAD system based on a personal computer PC with high-performance CPU and high resolution graphics display monitor
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Original CAD system configuration in 1970s and 1980s Host computer is a mainframe or large mini computer
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An engineering g g workstation is a stand-alone computer p system dedicated to one user and capable of executing graphics software and other programs requiring high-speed computational power
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This is a personal computer with a high-performance CPU and high resolution graphics display screen PC-based PC based CAD systems can be networked (as shown) to share files, output devices, and for other purposes
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Most closely closel associated with ith f functions nctions in manufacturing engineering, such as process planning and NC part programming CAM applications can be divided into two broad categories:
1. Man 1 Manufacturing fact ring planning 2. Manufacturing control
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Computer-aided process planning (CAPP) Computer-assisted NC part programming CAD/CAM assisted NC part programming Computerized machinability data systems Computerized work standards Cost estimating Production and inventory planning Computer-aided assembly line balancing
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Process monitoring and control Quality control Sh floor Shop fl control t l Inventory control Just-in-time production systems
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Concerned with the engineering functions in both design and manufacturing Denotes an integration of design and manufacturing activities by means of computer systems Goal is to not only automate certain phases of design and certain phases of manufacturing, but to also automate the transition from design to manufacturing In the ideal CAD/CAM system, the product design specification ifi ti residing idi i in th the CAD d data t b base would ld b be automatically converted into the process plan for making the product
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Includes all of the engineering functions of CAD/CAM Also includes the firm's business functions that are related to manufacturing Ideal CIM system applies computer and communications technology to all of the operational functions and information processing functions in manufacturing
From order receipt, Through design and production, To product shipment
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A systematic procedure for defining customer desires and requirements and interpreting them in terms of product features and process characteristics
A series of interconnected matrices are established between customer requirements and the technical features of a proposed new product
The matrices are a progression of phases in which customer requirements are first translated into product features, then into manufacturing requirements, and finally into quality procedures for controlling the manufacturing operations
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Shown as a series of matrices that relate customer requirements to successive technical requirements in a typical progression
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1. 2. 3. 4. 5. 6.
Identify customer requirements Identify product features needed to meet customer requirements Determine technical correlations among product features Develop relationship matrix between customer requirements and product features Comparative evaluation of input customer requirements Comparative evaluation of output technical requirements
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