computer aided process planning, approaches to capp, variant and generaive type
- 1. Process Planning • Link between product design and Manufacturing • Design output: Sketch • Production dept output: Physical Product • Process planning designs the bridge to convert sketch in to physical product
- 2. Process Planning • Determining the sequence of processing and assembly steps to make the product • Decides what types of equipment and tooling are required to fabricate the parts and assemble the product. • Concerned with logistics issues of making product • Deals with ordering the materials and obtaining the resource
- 3. Process Planner • One who performs the planning task • He should possess knowledge of: – Interpretation of design drawing: dimension tolerances and geometry related parameters – Processes and sequence: Minimum shifts and changeovers – Equipment selection: – Tools , dies, molds, … – Material handling methods: Hoist, crane, Fork lift, automated…. – Standard parts – Cutting conditions and time standards
- 4. Route sheet • Output of process planning • Includes.. – Material – Size – Operation description – Dept – Machine – Tooling – Setup and Cutting time
- 5. Part No Part Name Planner Checked By Date Page 1 Plate -- -- -- -- Material size No. Operation Description Dept Machine Tooling Set up Std. 10 making faces right angle by filing Fitting Files 5 min 1 hr 20 Locating centers 30 Drilling through holes dia 8 Drill D10 Drill J999 10 min 15 min 40 Tapping of dia 8 Fitting - Tape and tape wrench 1 0 min 35 min 50 Locating buttons 60 Drilling Lathe 70 Boring Operation
- 6. • Process planning for machining • Process planning for assembly
- 7. Sequence of processes required in part fabrication Secondary Processes Basic Process Property Enhancing Processes Finishing Process Raw Mat
- 8. Example Basic Process Starting Mat Secondary Pro Enhan. Proc Finishing Proc Sand Casting Sand casting Machining - Painting Rolling Sheet Metal Punching Bending Forming - Plating Painting Rolling and Bar drawing Bar Stock Machining Grinding Heat Treatment ‘’ Forging
- 9. Make or Buy decision • Factors to consider: – Cost – Availability of in-house process – Total production quantity – Anticipated product life – Standard – Current capacity of plant – Alternative supply need
- 10. Ex. • Buy: 20/unit for 100 unit • Make: – Raw Mat. Cost = 8 / unit – Direct labor cost= 6 / unit – Overhead = 9 / unit – Equipment fixed cost = 5 / unit • What’s your choice?
- 11. CAPP • Computer Aided process planning • Benefits: – Process standardization – Increased productivity of process planner – Reduced lead time – Improved legibility – Interfacing with other Cs i.e. CAM, CAD..
- 12. CAPP types • Retrieval CAPP Systems • Generative CAPP Systems
- 13. Retrieval CAPP Systems • Based on the principles of GT • Also called variant CAPP • GT: Group Technology – Concept of grouping parts together depending upon their similarities in operation sequence or geometry • Experts’ knowledge and standard process plans as per GT are needed as data base • Considerable work is required to collect and organize copious data
- 14. New part design
- 15. Derive GT Code number for part New part design
- 16. Derive GT Code number for part Search part family file for GT code number Part Family file New part design
- 17. Derive GT Code number for part Search part family file for GT code number Part Family file Selecting coding System and form part families Prepare standard process plans for part families Preparatory stage New part design
- 18. Derive GT Code number for part Search part family file for GT code number Part Family file Standard process plan file Selecting coding System and form part families Prepare standard process plans for part families Preparatory stage New part design
- 19. Derive GT Code number for part Search part family file for GT code number Retrieve standard process plan Part Family file Standard process plan file Selecting coding System and form part families Prepare standard process plans for part families Preparatory stage New part design
- 20. Derive GT Code number for part Search part family file for GT code number Retrieve standard process plan Edit existing plan or write new plan Part Family file Standard process plan file Selecting coding System and form part families Prepare standard process plans for part families Preparatory strange New part design
- 21. Derive GT Code number for part Search part family file for GT code number Retrieve standard process plan Edit existing plan or write new plan Process plan formatter Process plan (Route Sheet) Part Family file Standard process plan file Selecting coding System and form part families Prepare standard process plans for part families Preparatory strange New part design
- 22. Derive GT Code number for part Search part family file for GT code number Retrieve standard process plan Edit existing plan or write new plan Process plan formatter Process plan (Route Sheet) Part Family file Standard process plan file Selecting coding System and form part families Prepare standard process plans for part families Preparatory stage Other application programs New part design