Process planning approaches

Process Planning Approaches - 1.Variant(Retrieval) Approach.
2. Generative Capp Approach.with case studies.

1. Seminar presentation on Process Planning Approaches By, Chetan kumar Akshay s mangalgi M S RAMAIAH INSTITUTE OF TECHNOLOGY

2. Manual Systems Computer Aided systems Variant System Experimental Generative System Process Planning Approaches

3. Manually Prepared Process Plans

4. Computer Aids

5. Variant (Retrieval) CAPP System

6. Variant CAPP

7. Process plans are automatically generated by means of decision logic, formulae, technology algorithms and geometry based data There are two major components Geometry based:- define all geometric features for all the process related surface features like dimensions and tolerance and surface finish required. knowledge based :- the automatic matching of the part geometry requirements with the manufacturing capabilities using process knowledge in the form of decision logic and data Generative CAPP System

8. They rely less on group technology code numbers since the process, usually uses decision tree to categorize parts into families. Maintenance and updating of stored process plans are largely unnecessary. New Components can be planned as easy as existing components Advantages of Generative Process Plan

9. It can systematically produce accurate and consistent process plans. It leads to the reduction of cost and lead times of process plan. Skill requirement of process planer are reduced to develop feasible process plan. Interfacing of software for cost, manufacturing lead time estimation, and work standards can easily be done. Leads to the increased productivity of process planar. Advantages and Disadvantages CAPP over manual process planning

10. CAPP Software's

11. Case studies

12. 1. Computer Aided Process Planning for Freeform Surface Sheet Metal Features in Automotive Industry by, M. A. Saleh H.M.A.Hussein H.M.Mousa

13. This case study shows how Automotive body panels are manufactured using thin forming sheets by capp system. They developed CAPP system consists of two modules a) STEP AP203 b) process plan module. And cost estimation module are also incorporated in the system for punch and bending operation. Stamped or punched features in generative shape design are used to design automotive panels. Continued....

14. The application of the CAPP system for sheet metal is classified into three subgroups: CAPP for sheared parts CAPP for bend parts CAPP for drawn or formed parts Some other applications also taken into consideration such as punching, nibbling machines, and laser cut Machines.

15. Table 1. Input parameter for time estimation Above table illustrates operation time equation for punching and bending processes .

16. The designed part is created using CATIA V5R19 CAD system that supports STEP AP203 protocol translators. AutoCAPP Program is developed using Windows-based Microsoft Visual basic 2008 on a PC environment. Main construction of AutoCAPP program has the three modules of the program are as follows: 1. Generative process plan which include (Data extraction, feature recognition and generative CAPP). 2. Semi-generative CAPP module for automotive panels 3.Cost estimation of sheet metal process shown above Figure

17. Fig shows Main construction of AutoCAPP program.

18. Side wall panel of an automobile Header of an automobile side wall panel.

19. Generated CAPP of an automotive side wall panel.

20. This system generates and reports a process plan outlining the operation sequence,operation type, tools, machines, feature geometry, operation time, nd operation cost. AutoCAPP application with a user-friendly interface Was built and used for STEP data extraction, free form surface recognition etc CAPP of free form sheet applications, and sheet metal cost estimation of bending and punching operation.

21. This paper presents research work on developing a computer-aided casting process-planning system using case based reasoning. The nearest neighbour algorithm has been used for retrieval of a previous case (solution) that is closest to the current case. The complete methodology has been implemented in a web-based framework to enable early manufacturability assessment of castings through cost estimation and process simulation, both of which require process planning information. 2. Variant process planning of castings using nearest neighbour algorithm for case retrieval

22. The methodology comprises the following steps. Identifying the attributes of a casting for case retrieval Determining attribute weights using analytic hierarchy process Specifying the attribute values Retrieving one or more similar cases from the case base Adapting the selected case to handle the new problem and retaining the adapted case for future use. CBR METHODOLOGY FOR CASTING PROCESS PLANNING

23. hierarchy for determining attribute weights

24. Screening the process data base and case base the feasible processes for the new project are first identified by comparing the attribute values of the new project. The case base (database of old projects) is then screened to shortlist the cases that are manufactured by any one of feasible processes (for the new case) Only short-listed cases are considered for the next step. This helps in reducing the overall time for retrieving the most appropriate case Case retrieval

25. Determining the nearest neighbor After specifying the attribute values, the similarity of the new casting to a casting in the case base is determined and short-listed. the nearest three cases(with respect to the new case) are identified. The user can select any one of the nearest neighbour cases displayed by the process planning system Sim (N,O)= Similarity of new case to old case in the case base sim ( ni , oi )= Similarity of individual attribute values of new case to old case dist( ni , oi )= Distance between individual attribute values of new case to old case ni = Value of attribute i of old case in case base oi = Value of attribute i of new case

26. The next step is to adapt the process plan of the previous case to the new project at hand. If the new project is similar to a previous one, then the old process plan can be used directly and no adaptation is needed. Case adaptation involves modifying a process plan using the process planning library. The library stores information related to steps and process parameters required to perform each casting activity.

27. The case based reasoning methodology with the nearest neighbour algorithm and analytical hierarchy process proved to be effective and efficient. The computation time was further reduced by matching the casting process of previous cases with the feasible process of the new case. the system can be used by design engineers for manufacturability analysis through early cost estimation and quality prediction by simulation, both of which require process planning information CONCLUSIONS

28. Thank you