UNIT 1 PPCE.ppt
- 1. Process Planning and Cost Estimation Unit 1 - Introduction to Process Planning
- 2. Process planning Process planning consists of preparing set of instructions that describe how to manufacture the product and its design Process planning is the detailed specifications that list the operations, tools and facilities According to American society of tool and manufacturing engineers “ it is the systematic determination of the methods by which a product is to be manufactured competitively and economically ’’
- 4. Importance of process planning Process planning establishes the link between engineering design and manufacturing Process planning determines the production cost and profitability Process planning facilitates the feedback from shop floor to design engineering regarding the manufacturability of alternatives
- 5. Documentation of process planning
- 6. Typical filled route sheet
- 10. General information's from the Engineering Drawing Material of the component Number of parts to be produced Weight of the component Dimensions of the part Size and accuracy of the parts Dimensional and geometrical tolerances
- 11. Engineering drawing Universal language for engineers and most common form of engineers Orthographic projection drawings are commonly employed in engineering drawing (2D drawings) examples front, top and side views Accurate way of providing information
- 12. Types of drawing 1.Detailed drawings
- 13. 2. ASSEMBLY DRAWINGS – a) collective assembly drawing
- 14. b) COMBINED DETAILED ASSEMBLY DRAWING
- 15. Important parameters considered for process planners Dimensions Material specifications Material treatment Tolerances, limits and fits Surface finish
- 16. 1. Tolerances a) Dimensional tolerances If the dimension is specified in ‘mm’as 10±0.02, then the part will be acceptable if the dimension is manufactured to an actual size between 9.98 and 10.02mm General tolerances General tolerance notes apply to all unspecified dimensions on a drawing
- 17. B. Geometrical tolerance Permissible variation of form and location of a feature of the component TYPES OF GEOMETRICAL TOLERANCING
- 19. GENERAL REPRESENTATION OF TOLERANCE DRAWING
- 20. Example of Engineering drawing
- 22. ANGULARITY PROFILE OF A SURFACE
- 23. C. Limits and fits 1. Hole basis system Size of the hole is kept constant , shaft size is varied to get different fits 2. Shaft basis system size of the shaft is kept constant , hole size varies
- 24. Fit Fit represents the tightness or looseness between two mating parts. Between the shaft and hole 1. Clearance fit 2. Transition fit 3. Interference fit
- 26. SURFACE FINISH Surface finish is the depth of irregularities of a surface resulting from the manufacturing process used to produce it Basic types of surface irregularities a) form error b) roughness c) waviness
- 27. a) Form error - for longer wavelength deviation - results from large scale problems in the manufacturing process - Errors in machine tool ways , guides or spindles and inaccurate alignment of work piece b) Roughness - finest irregularities of a surface (longest wavelength) - results from a particular production process or material condition
- 28. c) waviness -more widely spaced longer deviations of a surface from its nominal surface - waviness generally caused by the vibration or heat
- 29. Symbols used in surface finish
- 31. Methods of process planning Process planning Manual Traditional Workbench Computer aided Varient Generative
- 32. 1. Manual process planning A) Traditional approach i ) manufacturing methods can be decided by his experience and resources available ii) process plans can be developed based of the previously available developed plans iii) each operation he refers to manuals to ascertain the company’s recommended tools, feeds and speed for the particular material onthe selected machine
- 33. B) Work book approach It involves developing workbooks of predetermined sequences of operation for given types of work pieces After carrying out the drawing interpretation and identified the manufacturing process required The sequence of predetermined operations can be selected from the work book
- 34. Advantages of manual process palnning Low cost Flexible to change the process plans easily Disadvantages Excessive clerical work Lack of consistency in planning Late design modifications
- 35. 2. Computer aided process Planning (CAPP) Process planning can be done with the help of computers To overcome the drawbacks of manual process planning computer aided process planning(CAPP) can be used TYPES OF CAPP Varient approach (Retrieval approach) Generative approach
- 36. a) Varient approach • It is similar to manual process approach as it retrieves a standard plan an modifies to suit for a given part • The standard plans are grouped according to group technology(GT) classification and coding • The process plans for the part under consideration is compiled by retrieving those of standard plans that are relevent
- 38. b) Generative approach • Developed completely a new plan for every part • Plans are produced by the computer means of decision logic ,formulaes,algorithms and geometric analysis • No need of human intervention
- 39. Benefits of CAPP Process rationalization and standardization CAPP helps in arriving at standard and consistent process plans Increased productivity of process planners Reduced lead time for process planning Improved legibility and readability Incorporation of other application programmes
- 40. SOME APPROACHES CAD CAM 2-D Drafting Process Planner • automatic drawing interpretation • gen. type plan generation Automatic part programming 3-D Solid Model canned/auto. cutter path cycle Feature based solid model automatic part programming • feature refinement • limited geometric reasoning • generative planning • seq may dictated by design 2-D Drafting • drawing interpretation • variant type plan generation • interactive part programming NC control 3-D CAD Model • interactive drawing interpretation • gen./variant type plan generation canned cutter path cycles • geometric reasoning • expert planner • no human decision
- 41. THE DEVELOPMENT OF CAPP 1960 1970 1980 1990 2000 Intelligence of the system Human Expert ? manual planning Data base GT variant system expert system geometric reasoning elementary machine learning ? technology
- 43. Factors Influencing Process Selection • Shape requirements(geometrical form) Example: solid shape, hollow shape, flat shape, flanged shape, concave shape, convex shape, cylindrical shape, presence of any part features such as groove, threaded shape, hole, chamfer, • Size or dimensional requirements Process capable of handling parts of small sizes and some processes can handle large sized parts economically and effectively
- 44. • Surface finish requirements Example : reaming process can provide a better surface finish in a hole when compared with drilling process • Tolerance requirements Example: grinding process always gives close tolerances when compared with turning process • Production volume requirements Example: no. of components required on a weekly, monthly or annual basis
- 45. • Material requirements Example : hardness, and strength characteristics of the material
- 46. Process selection parameters • Nature of part, including materials, tolerances, desired surface finish and operation required. • Method of fabrication including machining or assembling of similar parts or components. • Limitation of facilities including the plant and equipment available. • Possibility of likely product design changes to facilitate manufacturability or cost reduction.
- 47. • In-plant and outside materials handling systems • Inherent process to produce specified shape, surface, finish to give desired mechanical properties • Available skill level of operators for the production
- 48. Material Selection parameters • Functional requirements i) fatigue characteristics, ii) strength, iii) Hardness, iv) Electrical and thermal properties. • Reliability - consistency with which the material will meet all the products requirement throughout its service life
- 49. • Service life durability Years or hours of operation of the product to perform its function satisfactorily • Environmental Factors Temperature, humidity, corrosive • Aesthetics and appearance i) colour, texture, ii) lusture, smoothness and finish
- 50. • Compatibility with other materials during service -combination of materials used in a assembly • Producibility or manufacturability -Machinability of materials for machined components • Cost - Availability of the material
- 51. Equipment and Tooling selection
- 53. Factors considered for Equipment selection
- 54. I. TECHNICAL FACTORS 1. Physical size i) dimension ii) weight 2. Machine accuracy Able to manufacture the part within the specified dimensional and geometrical tolerance Machine accuracy capability should be checked to ensure the achievement of specified dimensional and geometrical tolerance
- 55. 3. Surface finish To ensure the achievement of specified surface finish requirements of the component in the design stage 4. Cutting forces Machining parameters such as feed, speed and depth of cut influence the various cutting forces Machine tool under consideration should be provided the calculated cutting force for the operation identified
- 56. 5. Machine power Power requirement of each operation is to be identified to ensure the power rating of the machine Power required = cutting force X cutting speed
- 57. II. OPERATIONAL FACTORS 1. Batch size 2. Capacity Production rate of the machine Should be capable of achieving specified output per unit time matching with master production schedule requirements (MPS)
- 58. 3. Availability Refers to the proportion time of machine availability to perform the work out of time Availability affects the reliability, and overall efficiency
- 61. Factors in Tooling selection
- 65. Shape/features produced by some common manufacturing processes
- 68. Selected treatments and their effects
- 70. General classification of assembly processes
- 71. Case study Process planning of an axle part
- 72. Axle part
- 75. Set up sketch for each operation for manufacturing of Axle