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Note for PROCESS PLANNING AND COST ESTIMATION - PPCE By ANNA SUPERKINGS

  • PROCESS PLANNING AND COST ESTIMATION - PPCE
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Fatima Michael College of Engineering & Technology Requires skilled process planner More possibilities for human error Increases paper work Inconsistent process plans results in reduced productivity COMPUTER AIDED PROCESS PLANNING (CAPP) To overcome drawbacks of manual process planning Computer Aided Process planning (CAPP) is used Provides interface between CAD and CAM Benefits Process rationalization and standardization Productivity improvement Product cost reduction Elimination of human error Reduction in time Reduced clerical effort and paper work Improved legibility Faster response to engineering changes Incorporation of other application programs RETRIEVAL CAPP SYSTEM It is also called as variant CAPP, widely used in machining applications Basic idea behind is, similar parts will have similar process plans Process plan for new part is created by recalling, identifying and retrieving an existing plan for a similar part, and making necessary modification for new part PROCEDURE FOR RETRIEVAL CAPP SYSTEM Retrieval CAPP system is based on principles of group technology (GT) and part classification and coding For each part family, standard process plan is prepared and stored in computer files Through classification and coding, code number is generated Standard plan is retrieved and edited for new part Advantages Once a standard plan has been written, variety of parts can be planned Requires simple programming and installation Understandable, and planner has control of final plan Easy to learn and easy to use Disadvantages Components to be planned are limited to similar components previously planned Requires experienced process planners to modify the standard plan for specific component Fatima Michael College of Engineering & Technology

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Fatima Michael College of Engineering & Technology New part design Derive GT code number for part Preparatory storage Search part family file for GT code number Select coding system and form part families Part family file Retrieve standard Standard Process plan Prepare standard process plan file process plans for part families Edit existing plan or write new plan rocess plan formatter Other applications such as cost estimating and work standards (Route sheet) Process plan Fatima Michael College of Engineering & Technology

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Fatima Michael College of Engineering & Technology GENERATIVE CAPP SYSTEM In this approach computer is used to synthesize or generate each individual process plan automatically without reference to any prior plan Generates the process plan based on decision logics and pre-coded algorithms. Computer stores the rules of manufacturing and equipment capabilities Specific process plan for specific part can be generated without any involvement of process planner Components of Generative CAPP system Part descriptor Subsystem to identify machine parameters Subsystem to select and sequence individual operations Database Report generator Advantages Generate consistent process plan rapidly New components can be planned as easily as existing components It has potential for integrating with automated manufacturing facility to provide detailed control information Drawbacks Complex and very difficult to develop 1.0 WORK STUDY First technique applied for increasing productivity. Considered as a valuable tool in increasing productivity. Definition: Work study is a generic term for the techniques of method study and work measurement. These techniques are used in the examination of human work in all its contexts. They lead systematically to the investigation of all the factors which affect the efficiency and economy at the work place in order to affect improvement. 1.1.METHOD STUDY Method study is the technique of systematic recording and critical examination of existing and proposed ways of doing work and developing an easier and economical method. 1.1.1 Objectives of Method Study 1. Improvement of manufacturing processes and procedures. Fatima Michael College of Engineering & Technology

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Fatima Michael College of Engineering & Technology 2. Improvement of working conditions. 3. Improvement of plant layout and work place layout. 4. Reducing the human effort and fatigue. 5. Reducing material handling 6. Improvement of plant and equipment design. 7. Improvement in the utility of material, machines and manpower. 8. Standardisation of method. 9. Improvement in safety standard. 1.2. BASIC PROCEDURE FOR METHOD STUDY The basic procedure for conducting method study is as follows: 1. Select the work to be studied. 2. Record all facts about the method by direct observation. 3. Examine the above facts critically. 4. Develop the most efficient and economic method. 5. Define the new method. 6. Install the new method 7. Maintain the new method by regular checking. 1. Select While selecting a job for doing method study, the following factors are considered: (a) Economical factors. (b) Human factors. (c) Technical factors. (a) Economical Factors The money saved as a result of method study should be sufficiently more. Then only the study will be worthwhile. Based on the economical factors, generally the following jobs are selected. (a) Operations having bottlenecks (which holds up other production activities). (b) Operations done repetitively. (c) Operations having a great amount of manual work. (d) Operations where materials are moved for a long distance. (b) Human Factors The method study will be successful only with the co-operation of all people concerned viz., workers, supervisor, trade unions etc. Workers may resist method study due to 1. The fear of unemployment. 2. The fear of reduction in wages. 3. The fear of increased work load. then if they do not accept method study, the study should be postponed. (c) Technical Factors To improve the method of work all the technical details about the job should be available. Every machine tool will have its own capacity. Beyond this, it cannot be improved. For example, a work Fatima Michael College of Engineering & Technology

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