1. GROUP TECHNOLOGY

2. GROUP TECHNOLOGY
GROUP TECHNOLOGY IS A MANUFACTURING
TECHNIQUE AND PHILOSOPHY TO INCREASE PRODUCTION EFFICIENCY BY EXPLOITING THE “UNDERLYING SAMENESS” OF COMPONENT
SHAPE, DIMENSIONS, PROCESS ROUTE, ETC.

3. History of GT

4. History of GT

5. First book formalize the concept:
Group Technology is the realization that many problems are similar, and that by grouping similar problems, a single solution can be found to a set of problems thus saving time and effort. (Solaja 73)
First book formalize the concept:
Mitrofanov,S.P. 1958, "The Scientific Principles of Group Technology"

6. WHY GROUP TECHNOLOGY?
AVERAGE LOT SIZE DECREASING
PART VARIETY INCREASING
INCREASED VARIETY OF MATERIALS
WITH DIVERSE PROPERTIES
REQUIREMENTS FOR CLOSER
TOLERANCES

7. OTHER BENEFITS OF GROUP TECHNOLOGY
EASIER TO JUSTIFY AUTOMATION
STANDARDIZATION IN DESIGN
DATA RETRIEVAL
EASIER, MORE STANDARDIZED PROCESS PLANS
INCREASES IN QUALITY

8. Role of GT in CAD/CAM integration
A rapid proliferation of numbers and variety of products, resulting in smaller lot sizes
Growing demand for closer tolerances, resulting in a need for economical means
Need for increased varieties of materials, heightening the need for more economical means of manufacturing
Increase in proportion of cost of materials to total product cost due to increasing labour efficiency, lowering acceptance scrap rates.
Increasing communications across the manufacturing functions with a goal of minimizing production costs and maximising production rates.

9. GT an important element of CAD / CAM integration
GT applications provides a common database for effective implementation of CAD/CAM, leading to succesful implementation of CIM.
Integration of design, manufacturing and quality
Provides a structure and save information about design and manufacturing attributes, process and manufacturing capabilities
Common database plays a vital role in the development and implementation of CAD/CAM.

10. Design attributes

11. Mnaufacturing attributes

12. Visual inspection method

13. GT an important element of CAD / CAM integration
GT codes retreive the data for process planning
Process planners may modify a process plan for existing process plan of a similar part.
The above criteria makes automation possible
Manufacturing plans are automating their operations by arranging in theor machines into cells.
This concept of cellular manufacturing system is based on GT concept

14. GT GT AFFECTS MOST EVERY OPERATING AND STAFF FUNCTION.
IT IS MORE THAN MERELY A TECHNIQUE, BUT A TOTAL
MANUFACTURING PHILOSOPHY.
DESIGN
ENGINEERING
DATA
PROCESSING
SALES
MAINTENANCE
INVENTORY
TOOL
ENGINEERING
PLANNING
ESTIMATING
PURCHASING
INDUSTRIAL
RELATIONS
ASSEMBLY
QUALITY
CONTROL
MANAGEMENT
MFG.
ENGINEERING
R & D
COST
ACCOUNTING GT
SHIPPING &
RECEIVING

15. FUNCTIONAL LAYOUTS ARE INEFFICIENT
Lathe
Milling
Drilling L L M M D D D D L L M M
Grinding L L M M G G
Assembly L L G G A A
Receiving and
Shipping G G A A
PROCESS-TYPE LAYOUT

16. GROUP TECHNOLOGY LAYOUTM D G A A
Receiving L M G L M D
Shipping

17. CELLULAR LAYOUT Department #2 Department #1 D D M I D I L

18. 2. PRODUCTION FLOW ANALYSIS
THREE TECHNIQUES TO FORM PART FAMILIES
1. TACIT JUDGMENT OR VISUAL
INSPECTION
MAY USE PHOTOS OR PART
PRINTS
UTILIZES SUBJECTIVE
JUDGMENT
2. PRODUCTION FLOW ANALYSIS
USES INFORMATION CONTAINED
ON THE ROUTE SHEET
(THEREFORE ONLY MFG. INFO)
PARTS GROUPED BY REQUIRED
PROCESSING
Cont’d

19. 3. CLASSIFICATION AND CODING
CODES GEOMETRY/DESIGN AND MFG.
INFO ABOUT A COMPONENT
CODES ARE ALPHANUMERIC STRINGS
EASIER TO USE FOR OTHER ANALYSES

20. TYPES OF CLASSIFICATION AND CODING SYSTEMS
GT CODING CAN BENEFIT MANY FACETS OF THE
FIRM AND FALL INTO ONE OF 3 CATEGORIES:
1. SYSTEMS BASED ON PART DESIGN
ATTRIBUTES
2. SYSTEMS BASED ON PART MFG.
3. SYSTEMS BASED ON DESIGN AND MFG.

21. LENGTH/DIAMETER RATIO TOLERANCES-----MACHINE TOOL
EXAMPLES:
PART DESIGN ATTRIBUTES
BASIC EXTERNAL SHAPE
BASIC INTERNAL SHAPE
MATERIAL
PART MFG. ATTRIBUTES
MAJOR PROCESSES
MINOR OPERATIONS
FIXTURES NEEDED
LENGTH/DIAMETER RATIO
SURFACE FINISH
TOLERANCES-----MACHINE TOOL
OPERATION SEQUENCE
MAJOR DIMENSION
TOOLING
BATCH SIZE

22. THIRTEEN PARTS WITH SIMILAR MANUFACTURING
EXAMPLE:
THIRTEEN PARTS WITH SIMILAR MANUFACTURING
PROCESS REQUIREMENTS BUT DIFFERENT
DESIGN ATTRIBUTES

23. DESIGN AND PART MANUFACTRUING ATTRIBUTES

24. GT CODE--A SEQUENCE OF NUMERICAL DIGITS THREE MAJOR STRUCTURES:
1. MONOCODE (OR HIERARCHICAL STRUCTURE)
A CODE IN WHICH EACH DIGIT AMPLIFIES THE
INFORMATION GIVEN IN THE PREVIOUS DIGIT
DIFFICULT TO CONSTRUCT
PROVIDES A DEEP ANALYSIS
USUALLY FOR PERMANENT INFORMATION
cont’d

25. MONOCODE OR HIERACHIAL CODE

26. HIERARCHICAL STRUCTURE
32XX
Hydraulic
Electrical
3231
3233
321X
323X
Mechanical
Power
Receiving
Transmission
322X
3232
No thread
UNC thread
UNF thread
3221
3223
3222

27. HIERARCHIALCODE FOR SPUR GEAR

28. POLYCODE OR ATTRIBUTE CODE
EACH DIGIT IS INDEPENDENT OF ALL OTHERS,
PRESENTS INFORMATION NOT DEPENDENT
ON PREVIOUS ONES
CODES ARE COMPACT
EASY TO USE AND DEVELOP
SUITABLE FOR COMPUTER ANALYSIS
LACKS IN DETAILS OF MONOCODE
POLYCODES ARE LARGER THAN MONOCODES

29. POLYCODE OR ATTRIBUTE CODE

30. MIXED CODE OR HYBRID CODE
HAS SOME DIGITS FORMING MONOCODES, BUT STRINGS THEM TOGETHER IN THE GENERAL ARRANGEMENT OF A POLYCODE
BEST FEATURES OF MONOCODE AND POLYCODE
SUBGROUPS ARE FORMED AS IN MONOCODE STRUCTURE
HYBRID CODE IS COMPACT THAN ATTRIBUTE CODE

31. Monocode
Polycode
HYBRID STRUCTURE

32. MIXED CODE OR HYBRID CODE

33. TECHNIQUE:
1. DETERMINE PART AND MACHINE REQUIREMENTS
2. NUMERICALLY CODE EACH PART
GEOMETRY (& SIZE)
MATERIAL
OTHER SPECIFICATIONS (TOLERANCE,
SURFACE FINISH)
3. FORM A FAMILY OF SIMILAR PARTS WHICH USE
(LARGELY) THE SAME SET OF MACHINE TOOLS
4. LAY OUT OF EACH CELL (A GROUP OF MACHINE
TOOLS) TO MAKE A FAMILY OF PARTS
5. DESIGN GROUP TOOLING

34. REDUCTION OF MFG. COSTS BY VARIOUS
STEPS OF GROUP TECHNOLOGY APPLICATIONS
(ADAPTED FROM HAM442)
NOT ALL COST SAVINGS ARE IMMEDIATE...
Improvements in Engineering Design
Materials Management & Purchasing Benefits
Production Control Benefits
Manufacturing Engineering Benefits
Tooling & Setup Benefits
Management Benefits
Overall Cost Reduction &
Increased Productivity
Time (months)

35. MAPPING FROM POPULATION
SPACE TO CODE SPACE
POPULATION
SPACE H P
CODE
SPACE C

36. CODING SYSTEMS More than 100 coding systems
- Opitz classification system
- MICLASS system
- DCLASS
- KK – 3
- CODE system
- CUTPLAN system
- Part Analog system
- COFORM
Brisch system
RNC system

37. OPITZ CLASSIFICATION SYSTEM
Developed by H. Opitz, University of Aachen, Germany
Alpha-numeric symbols used to represent various attributes
Digit sequence: ABCD
12345 – Form code – design attributes
Supplementary code – Manufacturing related attributes
ABCD - Secondary code – particular needs

38. OPITZ CLASSIFICATION SYSTEM

39. OPITZ CLASSIFICATION SYSTEM

40. MICLASS system MICLASS - Metal Institute Classification System
Also referred as Multiclass system
Digits – 12 to 30 digits.
First 12 codes are universal codes
Next 18 codes are supplementary codes

41. MICLASS system

42. MICLASS CODING
First 4 digits deal with form, main shape, shape elements and position
Next 4 dimensional information: Main dimension, ratio of various dimensions, auxillary dimensions
Digits 9 and 10 – Tolerance information
Next 18 digits – supplementary digits: information on lot size, piece time, cost data and operation sequence

43. MICLASS CODING
Parts can be coded using computer interactively – user responds to a series of questions asked by computer – on the basis of questions – computer assigns the code
It is difficult to make modifications, when the code does not provide necessary information

44. DCLASS Coding system
DCLASS – Design and Classification Information system
Comprises of 8 digits
First segment – 3 digits – denotes basic shape
Second segment – 4th digit –denotes the complexity of the part (holes, slots, heat treatment and special surface finishes)
Third segment – 5th digit – specify the overall size of the coded part
Fourth segment – 6th digit – Represents precision
Final segment – 7&8 digit – material type
- Easily computerised and hence it is a commercial coding system

45. DCLASS Coding system

46. Production flow analysis
Approach to part family and machine cell formation – pioneered by J. Burbridge
Parts that go through common operations are grouped into part families.
The machines used to perform these common operations may be grouped as a cell, consequently this technique can be used in facility layout (factory layout)

47. Production Flow Analysis (PFA)
Method for identifying part families and associated machine groupings
Part families are the workparts with identical or similar routings
Families used to form the machine cells
PFA uses manufacturing data rather than design data to identifying part families, which overcomes two part anomalies.

48. 3- Production Flow Analysis (PFA)
The procedure of Production flow analysis (PFA) consists of the following steps:
Data Collection. The minimum data needed in the analysis are the part number and operation sequence, which is obtained from process plans.
Sortation of process plans. A sortation procedure is used to group parts with identical process plans.
PFA Chart. The processes used for each group are then displayed in a PFA chart as shown below.

49. 3- Production Flow Analysis (PFA)
4. Clustering Analysis. From the pattern of data in the PFA chart, related groupings are identified and rearranged into a new pattern that brings together groups with similar machine sequences.

50. Advantages of PFA
Design data and PFA uses manufacturing data to identify part families
Overcomes two anomalies occur in part classification and coding
1st Anomaly : Basic geometries are quite different, but have same process routings
2nd Anomaly : Part geometries are similar, but require different process routings

51. Disadvantages of PFA
Does not provide any mechanism for rationalizing the manufacturing routings
No consideration being given to routing sheet, whether routing sheet are optimal or consistent or logical
Final part and machine grouping may be sub optimal, since process sequences from route sheets are prepared by different process planners. Routings may contain processing steps that are non-optimal, illogical and unnecessary

52. Facility Design in Group technology
It is the determination of how to arrange the machines in the shop
Facility layout or plant layout physical arrangement of production facilities
Configuration of departments, work centres and equipments in the conversion process
Layout objective is to economically meet required output quantity and quality

53. What Is Layout Planning?
Layout planning is deciding the best physical arrangement of all resources within a facility
Facility resource arrangement can significantly affect productivity
Two broad categories of operations:
Intermittent processing systems – low volume of many different products
Continuous processing systems – high volume of a few standardized products 53

54. Types of Layouts Four basic layout types consisting of:
Functional or Process layouts - Group similar resources together
Product or Line layouts - Designed to produce a specific product efficiently
Group or Hybrid layouts - Combine aspects of both process and product layouts
Fixed-Position layouts - Product is two large to move; e.g. a building 54

55. Product Layouts Product layout unique characteristics are:
Resources are specialized
Facilities are capital intensive
Processing rates are faster
Material handling costs are lower
Space requirements for inventory storage are lower
Flexibility is low relative to the market
© Wiley 2010 55

56. Product or Line Layout

57. Product layout

58. Group Technology GT Job shop production System
Batch production System
Mass production System
Job shop production System
Batch production System
Mass production System GT

59. Process Layouts Process layout unique characteristics include:
Resources used are general purpose
Facilities are less capital intensive
Facilities are more labor intensive
Resources have greater flexibility
Processing rates are slower
Material handling costs are higher 59

60. Process Layouts – con’t
Scheduling resources & work flow is more complex
Space requirements are higher 60

61. Product layout
Suitable for continuous mass production

62. Process layout

63. Designing Process Layouts
Step 1: Gather information:
Space needed, space available, identify closeness measures
Step 2: Develop alternative block plans:
Using trial-and-error or decision support tools
Step 3: Develop a detailed layout:
Consider exact sizes/shapes of departments and work centers including aisles and stairways
Tools like drawings, 3-D models, and CAD software are available to facilitate this process
© Wiley 2010 63

64. Special Cases of Process Layouts
A number of unique process layouts require special attention. We will look at two of these:
Warehouse layouts
Office Layouts
© Wiley 2010 64

65. Warehouse Layouts Warehouse Layout Considerations:
Primary decision is where to locate each department relative to the dock
Departments can be organized to minimize “ld” totals
Departments of unequal size require modification of the typical ld calculations to include a calculation of the “ratio of trips to area needed”
The usage of “Crossdocking” modifies the traditional warehouse layouts; more docks, less storage space, and less order picking
© Wiley 2010 65

66. Office Layouts Office Layout Considerations:
Almost half of US workforce works in an office environment
Human interaction and communication are the primary factors in designing office layouts
Layouts need to account for physical environment and psychological needs of the organization
One key layout trade-off is between proximity and privacy
Open concept offices promote understanding & trust
Flexible layouts incorporating “office landscaping” help to solve the privacy issue in open office environments
© Wiley 2010 66

67. Designing Product Layouts
Designing product layouts requires consideration of:
Sequence of tasks to be performed by each workstation
Logical order
Speed considerations – line balancing
© Wiley 2010 67

68. Designing Product Layouts – con’t
Step 1: Identify tasks & immediate predecessors
Step 2: Determine output rate
Step 3: Determine cycle time
Step 4: Compute the Theoretical Minimum number of Stations
Step 5: Assign tasks to workstations (balance the
line)
Step 6: Compute efficiency, idle time & balance delay
© Wiley 2010 68

69. Process vs. Product Layouts
Here are the characteristic differences between a process and product layout. 69

71. PROLIFERATION OF PARTS NOTE: SOME OF THE ABOVE ARE ALMOST THE SAME
SELECTION OF OPTICAL INSTRUMENT PARTS IN ONE COMPANY,
ILLUSTRATING THE SIMILARITY BETWEEN CERTAIN COMPONENTS
NOTE: SOME OF THE ABOVE ARE ALMOST THE SAME

72. GT FOR DESIGN APPLICATION
Design concept can be coded.
Code is a rough model of the
conceptual design.
Conceptual design
Coding (rough model)
Retrieval existing designs
Existing designs
Design modification
New Design
Design
archive
Retrieve designs of similar
shape or function and use
them as the examples.

73. Original shape of raw materials
FORM CODE
1st Digit
part class
5th Digit
additional
holes teeth &
forming
Supplim-
entary
code
Digit
Original shape of raw materials
Dimensions
Material
Accuracy
2nd Digit
main shape
3rd Digit
rotational
machining
4th Digit
plane surface
matching
Positions
with a
digit
External
shape
element
Main shape
Internal
shape
element
Rotational
machining
Main bore
& rotational
Machining
of plane
surfaces
Other holes
and teeth
teeth and
forming 1 2
Rotational 3 4 5
Special 6 7
Non-rotational 8
Opitz coding and classification system.
(Reprinted with permission from H. Opitz, A
Classification System to Describe Workpieces, Pergamon Press.) 9
Special

74. TYPICAL PROCESS PLANNING SYSTEM
Engineering
drawing
TYPICAL
PROCESS
PLANNING
SYSTEM
Process
planner
Code or
other form
of input
XXX
Process planning
system
Process
Industrial engineer
Time standard
Operation
instruction
Layout
Production planner
Scheduling
MPP
Part
programmer
APT Program
APT Processor
& post-processor

75. Process planning bridges design and
“PROCESS PLANNING” IS THAT FUNCTION WITHIN A MANUFACTURING
FACILITY THAT ESTABLISHES WHICH MACHINING PROCESSES AND
PARAMETERS ARE TO BE USED (AS WELL AS THOSE MACHINES CAPABLE
OF PERFORMING THESE PROCESSES) TO CONVERT (MACHINE) A PIECE
PART FROM ITS INITIAL FORM TO A FINAL FORM PREDETERMINED
(USUALLY BY A DESIGN ENGINEER) FROM AN ENGINEERING DRAWING.
(I.E. THE PREPARATION OF THE DETAILED WORK INSTRUCTIONS TO
PRODUCE A PART)
Process planning bridges design and
manufacturing
Bridge
Design
Manufacturing

76. VARIANT PROCESS PLANNING USES THE SIMILARITY AMONG COMPONENTS
TO RETRIEVE EXISTING PROCESS PLANS
(WHICH CAN BE MODIFIED)
OVERVIEW:
TWO STAGES FOR VP SYSTEMS
1. PREPARATORY STAGE
EXISTING PARTS CODED &
CLASSIFIED (I.E. GT IS A
PREREQUISITE)
PART FAMILIES ORGANIZED
STANDARD PLANS DEVELOPED
DATABASES CREATED
(NOTE: THIS STAGE IS LABOR INTENSIVE)
Cont’d

77. 1. PREPARATORY STAGE OF VARIANT PROCESS PLANNING
Part Drawing
Coding
Family One
Standard
Plan
File
Family Formation
(Indexed
by Family
Matrix)
Process Plan

78. 2. PRODUCTON STAGE OF VARIANT
PROCESS PLANNING
Coding
Family Search
Standard
Plan
File
Process Plan
Editing
Standard Plan
Retrieval