Classification Of Coding

1. CLASSIFICATION OF CODING
By
Mr. G. Dharanidaran

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. 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"

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

5. FLEXIBILITY
PRODUCTION CAPACITY
TRANSFER
LINE
SPECIAL
SYSTEM
FLEXIBLE
MANUFACTURING
SYSTEM
MANUFACTURING
Cells
STD. AND GEN.
MACHINERY
VOLUME
HIGH
VARIETY
LOW HIGH

6. EVERYDAY EXAMPLES
1. FAST FOOD CHAINS
2. DOCTORS, DENTISTS
AND ALSO MANUFACTURING
A FAMILY OF PARTS

7. PRODUCTION FAMILY

8. • LACK OF COMMON DATABASE FOR
MFG., DESIGN...
• DON’T “REDESIGN THE WHEEL”
• AUTOMATED PROCESS PLANNING
• DATABASE TO DRIVE THE
AUTOMATED FACTORY

9. BENEFITS OF GROUP TECHNOLOGY
REDUCTIONS IN
THROUGHPUT TIME
SET-UP TIME
OVERDUE ORDERS
PRODUCTION FLOOR SPACE
RAW MATERIAL STOCKS
IN-PROCESS INVENTORY
CAPITAL EXPENDITURES
TOOLING COSTS
ENGINEERING TIME AND COSTS
NEW PARTS DESIGN
NEW SHOP DRAWINGS
TOTAL NUMBER OF DRAWINGS
Cont’d

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

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

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

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

14. 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.
ATTRIBUTES
3. SYSTEMS BASED ON DESIGN AND MFG.
ATTRIBUTES

15. 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

16. 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

17. 2. POLYCODE (OR CHAIN-TYPE STRUCTURE)
EACH DIGIT IS INDEPENDENT OF ALL OTHERS,
PRESENTS INFORMATION NOT DEPENDENT
ON PREVIOUS ONES
• EASIER TO ACCOMMODATE
CHANGE
3. MIXED CODE
HAS SOME DIGITS FORMING MONOCODES, BUT
STRINGS THEM TOGETHER IN THE GENERAL
ARRANGEMENT OF A POLYCODE

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

19. UNFthread
Transmission
HIERARCHICAL STRUCTURE
Hydraulic Electrical
Mechanical
32XX
321X
322X
Nothread
UNC
thread
3222
323X
Power
Receiving
3232
3231 3233
3221 3223

20. MonocodePolycode Polycode
HYBRID STRUCTURE

21. REDUCTION OF MFG. COSTS BY VARIOUS
STEPS OF GROUP TECHNOLOGY APPLICATIONS
(ADAPTED FROM HAM442
)
Improvements in Engineering Design
Materials Management & Purchasing Benefits
Production Control Benefits
Manufacturing Engineering Benefits
Tooling & Setup Benefits
Management Benefits
Overall Cost Reduction &
Increased Productivity
NOT ALL COST SAVINGS ARE IMMEDIATE...
0 6 12 18 24 36
Time (months)

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

23. GT FOR DESIGN APPLICATION
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.
Design concept can be coded.
Code is a rough model of the
conceptual design.

24. 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

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

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

27. GROUP TECHNOLOGY LAYOUT
Shipping
L L M D
L M D
G
L M GG
A A
Receiving

28. Department #2
Department #3
Department #1
D D M I
D ML L I
D
M
L
M
I
CELLULAR LAYOUT

29. 1st Digit
part class
Positions
with a
digit
2nd Digit
main shape
3rd Digit
rotational
machining
4th Digit
plane surface
matching
5th Digit
additional
holes teeth &
forming
FORM CODE
Opitz coding and classification system.
(Reprinted with permission from H. Opitz, A
Classification System to Describe Workpieces, Pergamon Press.)
Special
Non-rotational
Special
Rotational
9
8
7
6
5
4
3
2
1
0
Internal
shape
element
Rotational
machining
Main bore
& rotational
machining
Other holes
and teeth
Other holes
teeth and
forming
Other holes
teeth and
forming
Machining
of plane
surfaces
Machining
of plane
surfaces
Machining
of plane
surfaces
External
shape
element
Main shape
Main shape
Main shape
Main shape
Supplim-
entary
code
Digit
6 7 8 9
Dimensions
Material
Originalshapeofrawmaterials
Accuracy

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

31. PROCESS PLANNING
“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)
Bridge
Design Manufacturing
Process planning bridges design and
manufacturing

32. 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

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

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