Computer Aided Design - Unit I Introduction
- 1. Product cycle- Design process- sequential and concurrent engineering- Computer aided design – CAD system architecture- Computer graphics – co-ordinate systems- 2D and 3D transformations- homogeneous coordinates - Line drawing - Clipping- viewing transformation-Brief introduction to CAD and CAM – Manufacturing Planning, Manufacturing control- Introduction to CAD/CAM –CAD/CAM concepts ––Types of production - Manufacturing models and Metrics – Mathematical models of Production Performance Unit I – Introduction
- 2. Product Cycle Product cycle integrate processes, people, data, and business and gives a product information for industries and their extended activity. Product cycle is the process of managing the entire lifecycle of a product from starting, through design and manufacture, to repair and removal of manufactured products. There are several Product cycle models in industry to be considered, one of the possible product cycle is given below Conceive Design Realize Service Product Cycle
- 3. Conceive Imagine, Specify, Plan, Innovate The first step is the definition of the product requirements based on company, market and customer. From this requirement, the product's technical data can be defined. In parallel, the early concept design work is performed defining the product with its main functional features. Various media are utilized for these processes, from paper and pencil to clay mock-up to 3D Computer Aided Industrial Design.
- 4. Design Describe, Define, Develop, Test, Analyze and Validate This is where the completed design and development of the product begins, succeeding to prototype testing, through pilot release to final product. It can also involve improvement to existing products as well as planned obsolescence. The main tool used for design and development is CAD. This can be simple 2D drawing / drafting or 3Dparametric feature based solid/surface modeling. This step covers many engineering disciplines including: electronic, electrical, mechanical, and civil. Besides the actual making of geometry there is the analysis of the components and assemblies.
- 5. Design Describe, Define, Develop, Test, Analyze and Validate Optimization, Validation and Simulation activities are carried out using Computer Aided Engineering (CAE) software. These are used to perform various tasks such as: Computational Fluid Dynamics (CFD); Finite Element Analysis (FEA); and Mechanical Event Simulation (MES). Computer Aided Quality (CAQ) is used for activities such as Dimensional tolerance analysis. One more task carried out at this step is the sourcing of bought out components with the aid of procurement process.
- 6. Realize Manufacture, Make, Build, Procure, Produce, Sell and Deliver Once the design of the components is complete the method of manufacturing is finalized. This includes CAD operations such as generation of CNC Machining instructions for the product's component as well as tools to manufacture those components, using integrated Computer Aided Manufacturing (CAM) software. It includes Production Planning tools for carrying out plant and factory layout and production simulation. Once details components are manufactured their geometrical form and dimensions can be verified against the original data with the use of Computer Aided Inspection Equipment (CAIE). Parallel to the engineering tasks, sales and marketing work take place. This could consist of transferring engineering data to a web based sales configuration.
- 7. Service Use, Operate, Maintain, Support, Sustain, Phase-out, Retire, Recycle and Disposal The final step of the lifecycle includes managing of information related to service for repair and maintenance, as well as recycling and waste management information. This involves using tools like Maintenance, Repair and Operations Management software.
- 8. Design process It is a process in which we initiate the design and come up with a number of design concepts and then narrow down to the single best concept. This involved the following steps. • Identification of customer needs • Problem definition, Gathering Information • Conceptualization, Concept selection Feasibility Study Preliminary Design Detailed design Production Consumption Retirement Distribution
- 9. Feasibility Study The Feasibility Study using analysis of several alternatives establishes the design concept as something which can be realized and accepted Some examples Designs can be futile unless satisfying the original need is feasible • At this stage, the product appears in abstract forms, but is they feasible? • Alternative solutions must be subjected to physical and economic analyses and be realizable from both (i) A building must be comfortable to live in: Heating, ventilation and air conditioning are required. Specify limits of temperature, humidity, velocity and fresh air constituency. (ii) National fossil fuel supplies are low: Alternative forms of energy supply are required. Specify amount and where they are needed, and any restrictions of space, time or pollution levels.
- 10. Preliminary Design • Main purpose is selection of the best possible solution from a choice of alternatives Make comparisons against given criteria & constraints • Must maintain an open mind; use your judgment
- 11. Detailed design • Aim is to produce a complete set of working drawings which are then transmitted to the manufacturer • This stage of design is far less flexible than those previous • Design should now reflect all of the planning both for manufacture and consumption stages Construction/testing of various components may be required
- 12. Production • Here, the device or system is actually constructed, and planning for this should have been incorporated into the design • Knowledge of the capability of the machines is required, since it must be possible to build and assemble the components as specified • Special jigs, fixtures and even machines may be required • Planning is vital; including quality control hold points, methods of inspection, standards for comparison etc... • Timing of construction may be important e.g. Climates
- 13. Distribution • Transportation of the manufactured article, complete or in subassembly form must be anticipated in the design • • Packaging, availability of vehicles, regulations for use of thoroughfares ,shelf/component life, warehouse storage facilities, special handling, environmental control of temperature and humidity may need to be addressed
- 14. Consumption • The product is now used by the consumer • If the design is effect, it will have met the need • The design may yet not be complete; redesigns and modifications may be required depending on field trials or consumer feedback • May need to consider maintenance of components and supply of spare parts or subassemblies
- 15. Retirement • The product will be discarded as its life cycle terminates • It may have become obsolete whilst still serviceable and therefore the design may not have been fully economical • Disposal and recovery of useful materials should have been included in the design Threats to safety should be guarded against
- 16. Sequential Engineering and Concurrent Engineering Sequential Engineering Concurrent Engineering Sequential engineering is the term used to explain the method of production in a linear system. The various steps are done one after another, with all attention and resources focused on that single task In concurrent engineering, various tasks are handled at the same time, and notes essentially in the standard order. This means that info found out later in the course can be added to earlier parts, improving them, and also saving time. Sequential engineering is a system by which a group within an organization works sequentially to create new products and services. Concurrent engineering is a method by which work several groups within an organization simultaneously to create new products and services.
- 17. Sequential Engineering Concurrent Engineering The sequential engineering is a linear product design process during which all stages of manufacturing operate in serial. The concurrent engineering is a non linear Product design process during which all stages of manufacturing operate at the same time. Both process and product design run in serial and take place in the different time. Both process and product design run in serial and take place in the different time Process and Product are not matched to attain optimal matching Process and Product are coordinated to Attain optimal matching of requirements for effective quality and delivery. Decision making done by only group of experts. Decision making involves full team Involvement.
- 18. Sequential Engineering Concurrent Engineering 1 2 3 4 1 2 3 4 1 – Requirement 2 – Product Development 3 – Process Development 4 - Prototype
- 19. Computer Aided Design - CAD The computers help in design and draft is commonly expressed by the term “Computer Aided Design” (CAD). A CAD system helps designer in various ways • Invites and promotes interaction through various input/output devices. • Allows manipulation of image (such as scalling, translation, rotation) in the computer screen. • Enable the designer to carry out the engineering analyses for stress, vibration, noise thermal distortions and more using FEA. • Design optimization through simulation and animation. • Automated drafting.