Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 5 Topic :
Group Technology
Definition and
Concepts
Segment A Topic:
ADVANCED
MANUFACTURING
SYSTEMS DESIGN
Group Technology
Definition and Concepts
Slide 2
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Overview
• Group Technology
– Definitions
– Concepts
Slide 3
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology –
Definition (1)
• Definition
– Group Technology is an operating
management philosophy based on the
recognition that similarities occur in the
design and manufacture of discrete parts.
– Group Technology exploits the similarities
among attributes of objects for the purpose
of performing a known function. The
attributes may be physical or process
oriented.
Slide 4
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology –
Definition (2)
• Alternate Definition (Webster)
– Group
• To Combine in a Group, to Assign to a Group,
Synonymous with Classify
– Technology
• An Applied Science, A Technical Method to
Achieve a Practical Purpose.
– GT => A Technical Method of Group
Formation
Slide 5
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology Applications
• Applications
– Design
• Similar Shapes
• Similar Processing
– Group Scheduling
• Sequence Dependant Set Ups
– Cellular Manufacturing (Decomposition of
Manufacturing Problem)
• Logical Cells
• Physical Cells
Slide 6
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology-Benefits
• Design
• Manufacturing
– Part Standardization
• Reduces Inventories
• Reduces Managerial
Complexity
– Access to
Manufacturing
Process Information
– Increased Designer
Productivity
Slide 7
– Increase Throughput
– Reduce Variability
– Improve Inventory
Management
– Reduce Set Up
– Improve Efficiency
– Improve Quality
– Simplify Procedures
– Reduce Tooling
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Classification and Coding
(1)
• Classification
– Grouping of Like Things
– Based on Physical or Process Attributes
– Logical and Systematic
• Coding
– Shorthand Notation for Complex Ideas
Slide 8
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Classification and Coding
(2)
• Classification
–
–
–
–
All - Embracing
Mutually Exclusive
Based on “Permanent” Characteristics
Reflect Users’ Objective and Nomenclature
• Coding
– Set of Symbols to which a Meaning has been
Assigned
– Will Database Technology Render Coding
Obsolete?
Slide 9
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology –
Grouping Attributes (1)
•
•
•
•
•
•
Shape
Form Features
Treatments
Functions
Size Envelopes
Tolerance
Slide 10
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology –
Grouping Attributes (2)
•
•
•
•
•
•
Surface Finish
Material Type/Condition
Quantity
Next Assembly
Raw Material Form
… (Others Based on
Application/User)
Slide 11
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Group Technology –
Grouping Methods
• Visual Inspection of Existing Parts
– Usually Done As Parts are Made
• Using Codes Defined During Design
– Pattern Recognition (Similarity)
• Features
• Processes
• Query
– Characteristics in Database
• Derived Attributes
• Additionally Input Attributes
Slide 12
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Monocode (1)
• Additional Digits Amplifies
Previous Digit
– Digit 1 = 1 -> Component
• Digit 2 = 4 ->Cylinder
– Digit 3 = Diameter, Digit 4 = Length, …
• Digit 2 = 5 -> Rectangular
– Digit 3 = Length, Digit 4= Width,
– Digit 5 = Height, etc
Slide 13
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Monocode (2)
• Additional Digits Amplifies
Previous Digit
– Digit 1 = 2 -> Assembly
• Digit 2 = ->Assembly Method
– 1 = Mechanical
• Digit 3 = -> Assembly Parameter
– IF Digit 2 =1, Digit 3= Type of Fastener
– IF Digit 2 = 2 (Weld), Digit 3 = Type (Arc,…)
Slide 14
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Monocode (3)
• Additional Digits Amplifies
Previous Digit
– Large Number of Combinations
Possible
• N1 x N2 x N3 x N4 x … Nn
– Difficult for Human Interpretation
– Cannot Sort on Single (Internal) Digit
• Meaning Dependant on Preceding Digit
Slide 15
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Polycode
• Each Digit Has Single Meaning
– Combinations Possible
• N1 + N2 + N3 + N4 + … + Nn
– Block Code – Not Difficult for Human
Interpretation
– Can Sort on Single (Internal) Digit
• Meaning Independent of Preceding Digit
– Long Codes May Result
Slide 16
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Mixed Codes
• Combines Mono- and Poly- Coding
– Attempt to Shorten Code while
Allowing a Larger Number of
Possibilities
Slide 17
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Is Coding Obsolete? (1)
• Should Actual Data be Used vs. a
Code Which Inexactly Represents
It?
– Attributes can be Derived and Stored
Automatically
• I.e., Largest Dimension = Length
• Use Database Search Engine/Query to
Find Groups
– Dynamic – Not Predefined, Flexible
Slide 18
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Is Coding Obsolete? (2)
• Not Quite Yet
– Coding Is Efficient
– Legacy Systems Use Coding
– Coding Embedded in Corporate
Culture
Slide 19
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Using Database Elements
for Grouping (1)
• Problems
– Speed of Search
– Requirement to “Exact Match”,
Control of Alphanumeric Elements
• Synonyms
– Is 1020 same as 1020 Steel?
• Spelling
– Is ALUM same as Alum same as Aluminium?
• Confusion
– Is 305 a Stainless or a Tool Steel?
Slide 20
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Using Database Elements
for Grouping (2)
• Solutions
– Indexing Data to Speed Search
• Quicker to Search Numeric Fields
– Use Multiple Stage Searches (Code?)
– Requirement to “Exact Match”,
Control of Alphanumeric Elements
• Use Drop-Down Selections to Control
Input (Must be all-inclusive)
• Can Allow Editable Drop Downs But
Maintenance is Required.
Slide 21
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Using Database Elements
for Grouping (3)
Maintenance
– Make System Data Driven
• No “Hard Coding”
– Higher Initial Cost
– Lower Maintenance
– Requires Diligence and Discipline
Slide 22
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 5 Topic :
Group Technology
Definition and
Concepts
Segment A Topic:
END OF SEGMENT
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 5 Topic :
Group Technology
Segment B Topic:
Example
ADVANCED
MANUFACTURING
SYSTEMS DESIGN
Group Technology
Example - GTSS
Slide 25
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
GTSS
• Group Technology Selection System
– Developed for DLA to Assist in Acquisition
– Developed as Part of the CATT Program
Slide 26
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Overall Mission
• Facilitate the Part Acquisition Process
• Identify Manufacturers with Particular
Capabilities
• Grouping of Parts by their Similarities
• Enable Mapping of Manufacturers to
Individual or Groups of Parts Using Group
Technology and Information Technologies
Slide 27
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Project Initiative
• Create National and Local Versions of Part
and Vendor Information System
• DLA Deployment (DSCR, DSCC)
– SCRA, DSCC, DSCR, OSU
– Captures only manufacturers with CAGE codes
• Oklahoma Deployment
– CATT -- CDS, GTI/ICI Group, OKC-ALC
– Captures Oklahoma manufacturers
Slide 28
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
GTSS Information Flow
High-Level Inputs
High-Level Outputs
Vendor
Database
SAMMS
FSC, NIIN, WSC,
Part Name, Part No.,
Cage Code, Dwg No./Rev.
SAMMS
Parts
to be coded
or procured
GTSS
Value Engr. Division
Update
TDPs
File of
GT cod ed
Parts
via
JEDMICS
Vendor
Data
Reports
Grouping
Mapping
Slide 29
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
System Functions
• NSN Data Entry
• Data Manipulation
– Identification Data
– GT Code Generation
• Vendor Data Entry
– Identification Data
– Capabilities
• Grouping
• Mapping
Slide 30
–
–
–
–
–
–
–
–
Computer Integrated
Manufacturing Systems
Entry/Edit Data
Error Checking
File Import/Export
Data Display (Search)
Data Display (Filter)
Data Display (Sort)
Vendor Queries
Report Generation
© 2000 John W. Nazemetz
Systems Design Concepts
• COTS Software
• Graphical Interface
– Windows 95
– PowerBuilder
– Oracle
– Easy to Use
– Intuitive
– Simple
• Security
• Group Technology
– Passwords
– User Levels
– Part Feature Based Part
and Vendor Codes
• On-Line Help
• Data Driven
– Ease of Maintenance
Slide 31
– Easy to Use
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Data Base Design
Concepts
• Balance Data Detail Level, DB Size
– Longer/Deeper Code
• Better Data Resolution, But
Data Base Grows Exponentially
– Use Auxiliary Fields to Reduce DB Size
• Hybrid Group Technology Code
– First Positions used to Define Rest of Code
– Same Code for Vendors and Parts
• Parts have a Single Code
• Vendors have Multiple Codes
Slide 32
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Data Base Design Concepts
(cont.)
• Impact of Code Length/Depth on DB
– Number of categories is product of number of
positions and number of possible selections
– Example: For a 10 position code with each code
position having 5 possible selections,
9,765,625 possible combinations/categories
• While a part would have only one code, a vendor who
can make everything has nearly 10 million.
Slide 33
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Data Base Design Concepts
(cont.)
• Impact of Auxiliary Fields
– If data is stored in an auxiliary field rather
than a code digit, DB size is reduced
– Example: if auxiliary field were used to
reduce a 10 position, 5 selection code to 7
positions, 5 selections, the number of
possible combinations is 78,125, not
9,765,625
Slide 34
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Data Base Design Concepts
(cont.)
• Data in GT Code
–
–
–
–
–
–
–
Material Type
[2]
Shape
[4]
Raw Mat’l Form [4]
Alt. Mat’l Form [4]
Size
[5,30]
Tolerances
[4]
Quality
[4]
• Data in Auxiliary
Fields
–
–
–
–
–
–
Material Spec Type
Material Spec
Plating
Treatment
Coating
Material Name
• approximately
53,760 possible
categories
Slide 35
Computer Integrated
Manufacturing Systems
• if these fields in code
@ 10 selections each,
one half trillion
categories
© 2000 John W. Nazemetz
GT Code Design Concepts
• First Two Code Positions Are Fixed
– Part Type (Initial Project Scope)
• Mechanical Piece Part
• Mechanical Subassembly
– Shape
• Prismatic, Cylindrical, Sculptured, Gears
• Not Used for subassemblies
Slide 36
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
GT Code Design Concepts
(cont.)
• Remaining Code Elements
– Piece Parts
•
•
•
•
•
Slide 37
Size
Tolerances
Raw Material Form
Alt. Raw Material Form
Quality Req.
– Subassemblies
Computer Integrated
Manufacturing Systems
•
•
•
•
•
•
Kitted/Assembly
Weight
Size
Fabrication/Machining
Tolerances
Quality Req.
© 2000 John W. Nazemetz
GUI Design Concepts
• Follows WINDOWS Standards
– Main Toolbar w/Dropdown menus
– Relocatable Icon Toolbar
– Right Mouse Button Activated Response
Windows
– Context Sensitive Help Available
– Dynamic Error Checking
Slide 38
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Summary/Assessment
• Concepts
– Theoretically Sound
– Method of Coding Manufacturers Was
Awkward
• Problems
– No Funds for Legacy Part Coding
• Use
– Used to Identify Suppliers
Slide 39
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 5 Topic :
Group Technology
Segment B Topic:
Example
END OF SEGMENT
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 5 Topic :
Group Technology
Grouping – Analysis
Methods
Segment C Topic:
ADVANCED
MANUFACTURING
SYSTEMS DESIGN
Group Technology
Grouping – Analysis Methods
Slide 42
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Overview
• Grouping/Analysis Methods
– Production Flow Analysis
• Rank Order Clustering
• Similarity Indexes
– Single Linkage
– Weighted (Production Volume)
• Mathematical Programming
• NOTE: The Following Slide Materials are From
Singh, Systems Approach to Computer
Integrated Design and Manufacturing, p. 490499.
Slide 43
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Production Flow Analysis
Slide 44
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Production
Flow
Analysis
Matrix
Manipulation
Row and Column
Sorting
Slide 45
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Rank Order Clustering (1)
Slide 46
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Rank Order Clustering (2)
Slide 47
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Rank Order Clustering (3)
Slide 48
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Single Linkage Cluster
Algorithm (1)
Slide 49
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Single Linkage Cluster
Algorithm (2)
Slide 50
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Single Linkage Cluster
Algorithm (3)
Slide 51
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Siefoddini and Wolfe
• Considers Production Volume (Weighted
Average)
Slide 52
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Exceptional Parts and
Bottleneck Machines
• Practical Approach to Problem of Costly
Equipment
• Allow InterCell Movement
• Elimination
– Generate Alternate Processing Plans
– Duplicate Machines
– Subcontracting Operations
• Still Has InterCell Transfers
Slide 53
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Alternate Cell
Configurations (SLCA)
Slide 54
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Alternate Cell
Configuration Analysis
Why
Cell
One?
Slide 55
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Mathematical Models
• Cell Design with Known Part Families
– Minimize Machine Investment
• Cell Design with Unknown Part Families
– Minimize Machine Investment
– Constrains Maximum Number of Machines in
Cell
• Cell Design With Unknown Part
Families, Key Machines
– Minimize Investment,
Movement/Backtracking
Slide 56
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Grouping Efficacy
• Method for Evaluating Goodness of Fit
Slide 57
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Group Technology
Grouping -- Analysis
Methods
Discussion Topic C:
END OF SEGMENT