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S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering

UNIT-1 FUNDAMENTALS OF COMPUTER GRAPHICS –PRODUCT CYCLE. S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering. CAD can be defined as the use of computer systems to perform certain functions in the design process.

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S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering

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  1. UNIT-1FUNDAMENTALS OF COMPUTER GRAPHICS –PRODUCT CYCLE S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering DHARANI KUMAR.S/AP/MECH/SECE

  2. CAD can be defined as the use of computer systems to perform certain functions in the design process. • CAM is the use of computer systems to plan, manage and control the operations of manufacturing plant through either direct or indirect computer interface with the plant’s production resources. DHARANI KUMAR.S/AP/MECH/SECE

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  5. The Product Cycle and CAD/CAM • In order to establish the scope and definition of CAD/CAM in an engineering environment and identify existing and future related tools, a study of a typical product cycle is necessary. The following Figure shows a flowchart of such a cycle. DHARANI KUMAR.S/AP/MECH/SECE

  6. Typical Product Life Cycle Production planning Design and procurement of new tools Order materials NC, CNC, DNC programming The Design Process Synthesis Design definitions, specifications, and requirements Collecting relevant design information and feasibility study Design needs Analysis The CAD Process Design modeling and simulation Design conceptualization Design documentation and communication Design evaluation Design optimization Design analysis The Manufacturing Process The CAM Process Process planning Production Quality control Packaging Shipping Marketing DHARANI KUMAR.S/AP/MECH/SECE

  7. The product begins with a need which is identified based on customers' and markets' demands. • The product goes through two main processes from the idea conceptualization to the finished product: • The design process. • The manufacturing process. The main sub-processes that constitute the design process are: • Synthesis. • Analysis. DHARANI KUMAR.S/AP/MECH/SECE

  8. The phases in design or General design procedure defined by Shingley model DHARANI KUMAR.S/AP/MECH/SECE

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  10. SHIGHELY Model Step 1 Recognition of Need • Problems in the existing products or potential for new products in the market have to be identified. Step 2 Definition of problem • The problem in the existing products or specification of the new product is specified as “Design Brief”. • It includes the specification of physical and functional characteristics, cost, quality, performance requirements etc DHARANI KUMAR.S/AP/MECH/SECE

  11. Step 3 Synthesis • In this stage the designer develops number of designs to meet the requirement of design brief. Step 4 Analysis and optimization • Each design from the synthesis stage is analyzed and the optimum one is selected. • Based on the analysis, improvements are made and redesigned. DHARANI KUMAR.S/AP/MECH/SECE

  12. Step 5 Evaluation In this stage, optimized design from the previous stage is checked for all specifications mentioned in the “Design Brief”. • Performance • Quality • Reliability • And other aspects of product Step 6 Presentation • After the product design passing through the evaluation stages, drawings, diagrams, materials specification, assembly lists, bill of materials etc. DHARANI KUMAR.S/AP/MECH/SECE

  13. Design process DHARANI KUMAR.S/AP/MECH/SECE

  14. Morphology of design • Morphology design refers the study of the chronological structure of design projects. It is defined by seven phases and their sub steps. Phase 1 Feasibility study / Conceptual design • To determine whether the need is original and valid. Phase 2 Preliminary design / Embodiment design • A surviving solution is tentatively accepted for further examination • Synthesis are initiated the major design parameters must be controlled • To maintained tolerances • Need customer feedback • testing DHARANI KUMAR.S/AP/MECH/SECE

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  16. Morphology of design Phase 3 Detailed design • To prepare major layout • Deciding various dimensions of components • Preparing specification • Testing the prototype and redesign Phase 4 Planning the production process • To prepare the detailed process planning sheets • Design of tool and fixture • Planning for the quality control system • Planning for the production personnel • Planning for the production control • Planning for the information flow feedback system DHARANI KUMAR.S/AP/MECH/SECE

  17. Morphology of design Phase V Planning for distribution • After the production of products, the products have to be distributed • Design the packaging of the product • Planning the ware housing system • Planning for promotional activity Phase VI Planning for consumption • Design for maintenance • Design for reliability • Design for safety • Design for convenience use • Design for economic operation DHARANI KUMAR.S/AP/MECH/SECE

  18. Morphology of design Phase VII Planning for Retirement • Design to reduce the rate • Design for the physical life to match • Design the product so that reusable materials DHARANI KUMAR.S/AP/MECH/SECE

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  21. Pahl and Beitz Model • Classification of Task • Conceptual Design • Emodiment design • Detail design Step 1 Classification of task • This phase involves the collection of information about the design requirements and the constraints on the design as well as describing the as design specification DHARANI KUMAR.S/AP/MECH/SECE

  22. Step 2 Conceptual design • This phase involves the establishment of function to be included in the design, and identification and development of suitable solution Step 3 Emodiment design • In this phase, the conceptual solution is developed in more detail, problems are resolved and weak aspects are eliminated Step 4 Detailed design • In this phase, dimensions, tolerances, materials and form of each individual components of the design are specified in detail which will be useful or manufacturing DHARANI KUMAR.S/AP/MECH/SECE

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  24. Ohsuga Model • Ohsuga describes the design as a series of stages progressing from requirements through the conceptual design and preliminary design to detail design. • If the proposal is unsuitable, then it is remodified. DHARANI KUMAR.S/AP/MECH/SECE

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  26. Earle Model The step in the design process prepared by Earle • Problem Identification can be one of the following two general types • Identification of design need – It is the beginning point of the design process • Identification of design criteria – It is the part of problem identification where the designer conducts an in depth investigation of specification which must be met by a new design. DHARANI KUMAR.S/AP/MECH/SECE

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  28. Problem Identification • Problem statement – It is written to begin the thinking process. This statement should be complete • Problem requirement- Needs to be positive requirement are listed must be achieved through a proper design. • Problem limitations – Negative factors are listed. • Sketches- To generate 2D or 3D model • Gather data – The gathered data should be graphed or easy interpretation DHARANI KUMAR.S/AP/MECH/SECE

  29. Preliminary ideas • Conduct brain storming session – To find out a specific problem for all ideas contribute by its members • Prepare sketches and notes - It can be used for create, modifying and developing. • Research existing designs – It can be obtained through research of similar products, Magazines etc. • Conduct survey – It can used to gather opinions and reactions. DHARANI KUMAR.S/AP/MECH/SECE

  30. Earle Model Design refinement Analysis To determine the cost, function and market appeal. • Several of better preliminary ideas are selected for suitable refinement. DHARANI KUMAR.S/AP/MECH/SECE

  31. Earle Model Decision Implementation It is the presentation of the final design concept in workable form as working drawings and specifications • At this stage a single design is accepted as solution to the design problem when compare to the cost of manufacturing , weight etc. DHARANI KUMAR.S/AP/MECH/SECE

  32. Concurrent Engineering Is a strategy where all the tasks involved in product development are done in parallel. Collaboration between all individuals, groups and departments within a company. • Customer research • Designers • Marketing • Accounting • Engineering DHARANI KUMAR.S/AP/MECH/SECE

  33. Concurrent Engineering Traditional Process = Linear Vs Concurrent Engineering = Team collaboration DHARANI KUMAR.S/AP/MECH/SECE

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  36. Concurrent engineering Characteristics of concurrent engineering Advantages of concurrent engineering As the design decisions are taken by a team of multidisciplinary experts, changes and modification on the product design will be faster It ensures better quality • Product responsibilities lie on the team of multi disciplinary group. • Integration of design, process planning and production will be achieved. • Product lead time will be less. DHARANI KUMAR.S/AP/MECH/SECE

  37. Sequential Engineering • Three major phases of conventional manufacturing process are design, process planning and manufacturing. • In design phase of the conventional manufacturing process, the product is designed on the basis of specification/requirements and method of manufacturing decided. DHARANI KUMAR.S/AP/MECH/SECE

  38. Sequential Engineering Errors changes and corrections Sequential engineering approach DHARANI KUMAR.S/AP/MECH/SECE

  39. Sequential Engineering Advantages Disadvantages As the decisions are taken by individuals, product modifications/changes will be slow. Since each activity is sequentially carried out, this approach requires longer lead time Because of above reasons, the product will be low • It is very simple, well defined method and allows everyone to remain on the same page. • It is an enforced discipline approach DHARANI KUMAR.S/AP/MECH/SECE

  40. Comparison b/w concurrent engineering and sequential engineering Design Planning Manufacture Testing Service DHARANI KUMAR.S/AP/MECH/SECE

  41. Roles of CAD in Design • It is accurately generated and easily modifiable graphical representation of the product. • The user can nearly view the actual product on screen. • It performs the complex design analysis in short time. By implementing finite element analysis ( FEA) methods • Static, dynamic and natural frequency analysis • Heat transfer analysis • Plastic analysis • Fluid flow analysis • Motion analysis • Tolerances analysis • Design optimization DHARANI KUMAR.S/AP/MECH/SECE

  42. CAD PROCESS • The computer can be beneficially used in the design process. • Geometric modeling • Wire frame modeling • Surface modeling • Solid modeling • Engineering analysis • Design review and evaluation • Automated drafting DHARANI KUMAR.S/AP/MECH/SECE

  43. Geometric modeling Geometric modeling Types of commands Commands used to generate basic geometric entities such as points, lines, circles etc. Command used to do manipulation work such as scaling, translation, rotation etc. Commands used for Boolean operation to form the image of the object in the computer screen • The mathematical description should be such that • The image of the object can be displayed and manipulated in the computer terminal. • The modification on the geometry of the object can be easily done • It can be stored in the computer memory and it can also be retrieved back . DHARANI KUMAR.S/AP/MECH/SECE

  44. Geometric modeling Engineering analysis Design Review and Evaluation The accuracy of the design can be checked and rectified if it is required in the computer screen itself. Another review features available in the modeling software are “interference checking” The dimensions of the mating parts can be checked • The computer can be used to aid the analysis work such as stress – strain analysis, heat transfer analysis etc. • The two types of important engineering analysis are as follows • Analysis for mass properties • Finite element analysis DHARANI KUMAR.S/AP/MECH/SECE

  45. CAD Process DHARANI KUMAR.S/AP/MECH/SECE

  46. Automated drafting • Automated drafting is the process of crating hard copies of design drawing. • The important features of a drafting software • Automated dimensioning • Scaling drawing • Generating sectional views • Orthographic view • Oblique view • Isometric view • Perspective view • Enlargement of minute part details DHARANI KUMAR.S/AP/MECH/SECE

  47. Application of CAD • Mechanical engineering sector is the largest user of CAD system • Manufacturing and forming a CAD/CAM • The application cover all types of manufacturing operations • Milling • Turning, • Punching etc DHARANI KUMAR.S/AP/MECH/SECE

  48. Application of CAD Civil engineering Electrical and electronics engineering Electric motor PCB design IC design etc. • Projects • Interior design • Static and dynamic analysis DHARANI KUMAR.S/AP/MECH/SECE

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