PROCESS PLANNING AND COST ESTIMATION - UNIT 1

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

8. Drawing interpretation

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

21. RUN OUT
CONCENTRICITY

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

42. PROCESS SELECTION

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

60. Tooling selection

61. Factors in Tooling selection

62. Tooling selection method

65. Shape/features produced by some common
manufacturing processes

67. Geometry classification matrix

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