TRAINING REPORT ON AUTO-CAD
Author Harpreet Singh
Scope of CAD/CAM/CAE Integrated CAD/CAM/CAE Softwares like Pro/Engineer, I-DEAS & CATIA help manufacturers optimize product concept early in Design process, enabling them to significantly improve product quality, while reducing product development time and cost Moreover people having 3D CAD/CAM/CAE knowledge have better chances of growth, immediate employability after completion of course, graduation and chances of jobs abroad. As the market economy opens more and more it has become extremely competitive and with this state of economy, skilled people play the most important role in organization. Hence it becomes imperative on the part of top Tool Room Training centers and Engg. Colleges to especially look for new initiatives towards improving the skills and knowledge of students. An emerging trend of Engg. Education in Tool Room and the world is the rapid incrementation of CAD/CAM/CAE software as an essential part of curriculum.
The primary reasons for this trend are enumerated as follows: Rapid shift from manual Design and Production system of Engg. Industry to highly productive quality and cost effective CAD/CAM/CAE system. In fact most of Tool and Die, Automotive, Heavy Engg., Industrial Equipment industry etc. in India and the World are totally working on CAD/CAM/CAE equipment. In continuation in above points many of companies as recruiters are looking at CAD/CAM/CAE knowledge as part of essential profile of recruiting students. Knowledge of CAD/CAM/CAE system shall be an added weapon for students seeking admission to post graduate M.S. courses and jobs abroad. These CAD/CAM/CAE systems shall prove to be an excellent tool for Industry, Research setup for Professors and Academically Bent Students. The question, Which are the industries that need more skilled man power and what for these segments skill sets are available, such of these segments are: Tool Room
Process M/C
M/C Tool
Defence
Automobile
Auto Ancillaries
Heavy Engg. Industries
WORKING WITH CAD/CAM/CAE TECHNOLOGY Essentially design is a decision making process where the discretion and knowledge of the designer play a great role. While man still finally controls decision-making, the computer has served to ease the designer’s task.
CAD
CAM
TOOL PATH GENERATION
MASTER MODELER
SHEET METAL DESIGN
STATIC ANALYSIS (WHEN BODY IS IN STATE OF REST)
MOLD DESIGN
CAE
SIMULATION
PIPE DESIGN
DYNAMIC ANALYSIS (WHEN BODY IS IN STATE OF MOTION)
GEOMETRIC MODELLING: Design involves the development of the shape and dimensions of a component. During designing several factors are to be considered simultaneously. Some of them are stress requirements, method of manufacture. Geometric modeling is the first step in CAD. A geometric model is created on the screen using different techniques. Once creating this model can be easily altered in geometry and configuration to yield a satisfactory shape. The next step is deciding on the exact dimensions. The results of geometric modeling will further be use by CAM in the preparation of NC tapes for the component.
ENGINEERING ANALYSIS: The most important function of CAD is engineering analysis. Engineering analysis basically involves deciding the exact dimensions of the component. These values have to be arrived at by analyzing the component in terms of the loads it has to withstand in function. CAD provides sophisticated method like the finite element technique. Unsatisfactory design may require several iteration of the whole process. The computer scores over the human in its capabilities of rapid information retrieval, numerical processing and repeating a process without fatigue.
SIMULATION: Simulation, in the CAD/CAM context, means duplicating on the video screen a replica of the actual physical situation the designed component is likely to be in. for instance, an aeroplane will be subjected to wind loads. In the conventional method, the aeroplane will be tested in a wind tunnel using a prototype. This is an expensive and inflexible process, expensive because of the physical construction of the wind tunnel and the prototype, inflexible because it may not be possible to test various sizes and shape under a set of test condition. Computer simulation gets rid of both these limitations. It involves the testing of a graphic model whose size and shape can be varied at will. Computer simulation does not completely do away with prototype testing. A near perfect shape can be determined using simulation, which can later be tested with a prototype under test conditions.
DRAFTING: The logical step would be to produce a drawing of the component. A drawing is dispensable for the production of the component. Not only the components designed by engineering analysis, but also complex layouts,
assemblies can be created interactively and plotted in about one tenth of the normal time. Automated drafting has resulted in enormous productivity gains in terms of time, labour and expenses.
EXPERT SYSTEMS: The latest development in CAD is the use of Expert systems. An Expert system has an “ intelligent data-base” called knowledge base and reasoning logic. It may contain, for example, the details of the breakdowns that occurred in the industry. On a later date, the user has only to feed in the conditions under which a breakdown occurred. The expert system discovers the reason for the breakdown. This is only one application of expert systems. Wherever decision making under multiple constraints is involved expert systems are used as logic support systems.
SYSTEM DESIGN CYCLE (Conventional design cycle) For solving any design problem or engineering problem, the general procedure may be followed. RECOGNITION OF A NEED
SPECIFICATION AND REQUIREMENTS
FEASIBILITY STUDY
CREATIVE DESIGN SYNTHESIS
PRELIMINARY DESIGN AND DEVELOPEMENT
DETAILED DESIGN
PROTOTYPE BUILDING AND TESTING
DESIGN FOR PRODUCTION
PRODUCT RELEASE
RECOGNITION OF A NEED This aspect of design can have its origin in many numbers of sources. Customer reports on the product function and quality may force a redesign. The starting point of a design project is a hypothetical need which may have been observed in socio-economic scene. The need may be existing or may not yet exist, but the evidence may be existing that the need is latent. The following points will help at this stage: 1. 2. 3. 4.
Study the nature of the need. Establish the need reasonably well to the extent possible. Make primitive statement of need. Do reconnaissance study with respect to qualitative and quantitative aspects.
SPECIFICATION AND REQUIREMENTS Once a need has been established, its requirements must be carefully spelled out. Very often the specifications are stated in such general terms as to indicate that the consumer has only a vague idea of what he wants. In these requirements design and performance requirements are carefully stated. Also, the specifications are prepared keeping in mind the production competence and capability of the company.
FEASIBILITY STUDY Once the problem’s need has been established and the specifications have been prepared, accepted and submitted, the feasibility study is done. The purpose of this study is to check the possibility of success or failure of the purposed project both from technical and economic standpoint. In this study, various questions are to be answered. 1. Is any natural law being defied? 2. Are some of the specifications beyond what is technically available at present? 3. Is there any dependence on source materials? 4. Will the cost of the end product be too high? The persons doing the feasibility study will be the engineers with strong design background, knowledge of engineering science, a good knowledge of
material usage, knowledge of production methods and requirements of the sales department.
CREATIVE DESIGN SYNTHESIS Once the feasibility of the design is established, the creative design synthesis has to be done. Here, the designer can act as engineer, inventor, artist all in one, because now he is called upon to create. The quantities of the new design will be: 1. The quality of newness or uniqueness. 2. Things, which are either useful or appreciated, are called creative. Creative things are sometimes either purposeful or beautiful or both. 3. The third quality in the design solution will be that it will have simplicity. A solution having the qualities of newness and useful or appreciated but complex would not be known as a creative solution.
PRELIMINARY DESIGN AND DEVELOPMENT After the process of creativity design is complete, there will be one or more possible designs that satisfy the given set of specifications and requirements. It then becomes necessary to decide which of the solutions to choose for the preliminary design and development stage. Note, this stage is primarily concerned with checking the validity of the functional and overall size requirements of the specifications. The stages of the preliminary design can be summarized as below: 1. Selection of the most useful solution from the several suggested solutions. 2. Formulation of useful model preferably mathematical for this selected solution. 3. Analysis of this model. 4. Prediction of performance. 5. Preparing layout of the selected solution, making a check for its function.
DETAILED DESIGN Many designers often miss many of the activities of the detailed design phase of the design process, particularly for smaller jobs, because so much of the detailing in the sense of component design is already done in the preliminary design phase. This phase of the design work consists of two major activities:
(1) (2)
Detailing the parts, component and their assembly. Going into sufficient details of manufacture in implementing the design.
The second phase as indicated earlier requires a good knowledge of manufacturing process. The method of manufacturing should be such that the following are avoided. (1) Heavy weight of material (2) Reclamping of work (3) Special purpose tools (4) Finishing operations
PROTOTYPE BUILDING AND TESTING After completing all the details, the sub-assemblies and assembly drawings including the materials and parts list, the completed design is sent to the prototype or model shop for fabrication. At this juncture the parts are fabricated, commercial components are purchased, and the machine or system, after having been assembled, is ready for evolution and testing. This testing can help in: 1. Producing acceptable performance 2. To generate new design information 3. To develop improved design concepts 4. To increase validity of the results.
DESIGN FOR PRODUCTION In addition to being functionally sound, a product must have sales appeal and must be competitive in price. In order for a product to be made economically, it must be designed so that the most appropriate material and processes will be utilized. This is called “ design for production”. For large scale manufacturing, any of these processes may be more economical than individual part machining.
PRODUCT RELEASE Production prototype are usually made and tested, and any drawback that can be easily corrected is generally referred back to preliminary design and development or to detailed design for alteration.
ADVANTAGES OF CAD CAD can make a draft men much more efficient. Depending upon the drafting task, two to ten times productivity improvement is not uncommon when using a CAD system .The following are the advantages of using CAD over manual drafting: -
REVISIONS: One of the most time-consuming tasks that a draft man performs is making changes to existing drawings. With a CAD system, revisions are much faster than manual methods. After a drawing has been completed, it is stored and can be recalled at any time to make changes easily.
REPITITION: Simple symbols or more complex ones , are created by drawing them with the CAD system and storing them away to be used at any time. Once a drawing has been produced and stored in the computer’s memory, it does not have to be drawn again if it is part of another drawing. Parts of previous drawings can be combined to produce new drawings.
ACCURACY: Dimensions are keyed-in using the computer keyboard or menu instead of reading a scale. Mating parts can be checked for fit by having the computer match the parts on the screen before hard copies are produced.
SPEED: In almost all areas of drafting, CAD is faster than manual drawing. This is especially true as the operator becomes more proficient through continued use of the system
NEATNESS: After the drawing has been produced on screen, it can be drawn on paper with a plotter. The mechanical plotting of a drawing produces clean, accurate and neat drawings using proper line weight and consistency, and sharp, consistent lettering.
COST: In the past, CAD systems were an expensive alternative to manual drafting, and only major industrial corporations could afford them. Now, because of reduced cost of memory, increased competition, and improved software and computer technology CAD systems are affordable to most drafting-design offices.
DIFFERENT TYPES OF CAD/CAM SOFTWARE 1. INTEGRATED CAD/CAM SYSTEM - Pro/engineer, I-DEAS CATIA, UNIGRAPHICS are integrated CAD/CAM system. We can do design/ analysis/ generation of tool path in same environment.
2. Point/Standalone solution- Softwares, which give only one solution out of DESIGN, MANUFACTURING & ANALYSIS are called point solution software. Like AUTOCAD gives only drafting solution, master cam gives manufacturing solution& ANSYS, NASTRAN, ADAMS, ABAQUS gives only analysis solution.
Why industries switches towards 3-d technology
Because 3-d model is centreled to all the activities pertaining to analysis,manufacturing,product concept& customer requirements.
