advanced manufacturing systems design © 2000 john w. nazemetz lecture 5 topic : group technology...
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Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Lecture 5 Topic :Lecture 5 Topic : Group Technology Group Technology
Segment A Topic:Segment A Topic: Definition and Definition and ConceptsConcepts
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 2
ADVANCED ADVANCED MANUFACTURING MANUFACTURING SYSTEMS DESIGNSYSTEMS DESIGN
Group Technology Group Technology
Definition and ConceptsDefinition and Concepts
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 3
OverviewOverview
• Group TechnologyGroup Technology
– Definitions
– Concepts
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 4
Group Technology – Group Technology – Definition (1)Definition (1)
• DefinitionDefinition– 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.
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 5
Group Technology – Group Technology – Definition (2)Definition (2)
• Alternate Definition (Webster)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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 6
Group Technology -Group Technology -ApplicationsApplications
• ApplicationsApplications– Design
• Similar Shapes• Similar Processing
– Group Scheduling• Sequence Dependant Set Ups
– Cellular Manufacturing (Decomposition of Manufacturing Problem)• Logical Cells• Physical Cells
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 7
Group Technology-Group Technology-BenefitsBenefits
• DesignDesign– Part Standardization
• Reduces Inventories• Reduces Managerial
Complexity
– Access to Manufacturing Process Information
– Increased Designer Productivity
• ManufacturingManufacturing– 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. NazemetzSlide 8
Classification and Classification and Coding (1)Coding (1)
• ClassificationClassification– Grouping of Like Things– Based on Physical or Process
Attributes– Logical and Systematic
• CodingCoding– Shorthand Notation for Complex Ideas
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 9
Classification and Classification and Coding (2)Coding (2)• ClassificationClassification
– All - Embracing– Mutually Exclusive– Based on “Permanent” Characteristics– Reflect Users’ Objective and
Nomenclature
• CodingCoding– Set of Symbols to which a Meaning has
been Assigned– Will Database Technology Render
Coding Obsolete?
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 10
Group Technology – Group Technology – Grouping Attributes (1)Grouping Attributes (1)• ShapeShape• Form FeaturesForm Features• TreatmentsTreatments• FunctionsFunctions• Size EnvelopesSize Envelopes• ToleranceTolerance
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 11
Group Technology – Group Technology – Grouping Attributes (2)Grouping Attributes (2)
• Surface FinishSurface Finish• Material Type/ConditionMaterial Type/Condition• QuantityQuantity• Next AssemblyNext Assembly• Raw Material FormRaw Material Form• … … (Others Based on (Others Based on
Application/User)Application/User)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 12
Group Technology – Group Technology – Grouping MethodsGrouping Methods
• Visual Inspection of Existing PartsVisual Inspection of Existing Parts– Usually Done As Parts are Made
• Using Codes Defined During DesignUsing Codes Defined During Design– Pattern Recognition (Similarity)
• Features• Processes
• QueryQuery– Characteristics in Database
• Derived Attributes• Additionally Input Attributes
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 13
Monocode (1)Monocode (1)
• Additional Digits Amplifies Additional Digits Amplifies Previous DigitPrevious 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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 14
Monocode (2)Monocode (2)
• Additional Digits Amplifies Additional Digits Amplifies Previous DigitPrevious 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,
…)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 15
Monocode (3)Monocode (3)
• Additional Digits Amplifies Additional Digits Amplifies Previous DigitPrevious 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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 16
PolycodePolycode
• Each Digit Has Single MeaningEach 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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 17
Mixed CodesMixed Codes
• Combines Mono- and Poly- Combines Mono- and Poly- CodingCoding– Attempt to Shorten Code while
Allowing a Larger Number of Possibilities
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 18
Is Coding Obsolete? (1)Is Coding Obsolete? (1)
• Should Actual Data be Used vs. Should Actual Data be Used vs. a Code Which Inexactly a Code Which Inexactly Represents It?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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 19
Is Coding Obsolete? (2)Is Coding Obsolete? (2)
• Not Quite YetNot Quite Yet– Coding Is Efficient– Legacy Systems Use Coding– Coding Embedded in Corporate
Culture
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 20
Using Database Using Database Elements for Grouping Elements for Grouping
(1)(1)• ProblemsProblems
– 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?
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 21
Using Database Using Database Elements for Grouping Elements for Grouping
(2)(2)• SolutionsSolutions
– 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.
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 22
Using Database Using Database Elements for Grouping Elements for Grouping
(3)(3)MaintenanceMaintenance
– Make System Data Driven•No “Hard Coding”
– Higher Initial Cost– Lower Maintenance
– Requires Diligence and Discipline
Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Lecture 5 Topic :Lecture 5 Topic : Group Technology Group Technology
Segment A Topic:Segment A Topic: Definition and Definition and ConceptsConcepts
END OF SEGMENTEND OF SEGMENT
Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Lecture 5 Topic :Lecture 5 Topic : Group Technology Group Technology
Segment B Topic:Segment B Topic: Example Example
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 25
ADVANCED ADVANCED MANUFACTURING MANUFACTURING SYSTEMS DESIGNSYSTEMS DESIGN
Group Technology Group Technology
Example - GTSSExample - GTSS
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 26
GTSSGTSS
• Group Technology Selection SystemGroup Technology Selection System– Developed for DLA to Assist in
Acquisition– Developed as Part of the CATT Program
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 27
Overall MissionOverall Mission• Facilitate the Part Acquisition ProcessFacilitate the Part Acquisition Process• Identify Manufacturers with Particular Identify Manufacturers with Particular
CapabilitiesCapabilities• Grouping of Parts by their SimilaritiesGrouping of Parts by their Similarities• Enable Mapping of Manufacturers to Enable Mapping of Manufacturers to
Individual or Groups of Parts Using Individual or Groups of Parts Using Group Technology and Information Group Technology and Information TechnologiesTechnologies
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 28
Project InitiativeProject Initiative• Create National and Local Versions of Create National and Local Versions of
Part and Vendor Information SystemPart and Vendor Information System• DLA Deployment (DSCR, DSCC)DLA Deployment (DSCR, DSCC)
– SCRA, DSCC, DSCR, OSU– Captures only manufacturers with CAGE
codes
• Oklahoma DeploymentOklahoma Deployment– CATT -- CDS, GTI/ICI Group, OKC-ALC– Captures Oklahoma manufacturers
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 29
GTSS I nformation Flow
GTSSValue Engr. Division
TDPsvia JEDMICS
VendorData
Partsto be codedor procured
FSC, NIIN, WSC,Part Name, Part No.,Cage Code, Dwg No./Rev.
High-Level Inputs
SAMMS
File of GT coded
Parts
ReportsGroupingMapping
High-Level Outputs
SAMMS
Update
VendorDatabase
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 30
System FunctionsSystem Functions
• NSN Data EntryNSN Data Entry– Identification Data– GT Code Generation
• Vendor Data EntryVendor Data Entry– Identification Data– Capabilities
• GroupingGrouping• MappingMapping
• Data ManipulationData Manipulation– Entry/Edit Data– Error Checking– File Import/Export– Data Display (Search)– Data Display (Filter)– Data Display (Sort)– Vendor Queries– Report Generation
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 31
Systems Design Systems Design ConceptsConcepts
• COTS SoftwareCOTS Software– Windows 95– PowerBuilder– Oracle
• SecuritySecurity– Passwords– User Levels
• Data DrivenData Driven– Ease of Maintenance
• Graphical InterfaceGraphical Interface– Easy to Use– Intuitive– Simple
• Group Technology Group Technology – Part Feature Based Part
and Vendor Codes
• On-Line HelpOn-Line Help– Easy to Use
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 32
Data Base Design Data Base Design ConceptsConcepts
• Balance Data Detail Level, DB SizeBalance 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 CodeHybrid 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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 33
Data Base Design Data Base Design Concepts Concepts (cont.)(cont.)
• Impact of Code Length/Depth on DBImpact 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.
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 34
Data Base Design Data Base Design Concepts Concepts (cont.)(cont.)
• Impact of Auxiliary FieldsImpact 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
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 35
Data Base Design Data Base Design Concepts Concepts (cont.)(cont.)
• Data in GT CodeData 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]• approximately
53,760 possible categories
• Data in Auxiliary Data in Auxiliary FieldsFields– Material Spec Type– Material Spec– Plating– Treatment– Coating– Material Name
• if these fields in code @ 10 selections each, one half trillion categories
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 36
GT Code Design GT Code Design ConceptsConcepts
• First Two Code Positions Are FixedFirst Two Code Positions Are Fixed– Part Type (Initial Project Scope)
• Mechanical Piece Part• Mechanical Subassembly
– Shape• Prismatic, Cylindrical, Sculptured, Gears• Not Used for subassemblies
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 37
GT Code Design GT Code Design Concepts Concepts (cont.)(cont.)
• Remaining Code ElementsRemaining Code Elements– Piece Parts
• Size • Tolerances• Raw Material Form• Alt. Raw Material Form• Quality Req.
– Subassemblies• Kitted/Assembly• Weight• Size• Fabrication/
Machining• Tolerances• Quality Req.
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 38
GUI Design ConceptsGUI Design Concepts• Follows WINDOWS StandardsFollows WINDOWS Standards
– Main Toolbar w/Dropdown menus– Relocatable Icon Toolbar– Right Mouse Button Activated
Response Windows– Context Sensitive Help Available– Dynamic Error Checking
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 39
Summary/AssessmentSummary/Assessment• ConceptsConcepts
– Theoretically Sound– Method of Coding Manufacturers Was
Awkward
• ProblemsProblems– No Funds for Legacy Part Coding
• UseUse– Used to Identify Suppliers
Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Lecture 5 Topic :Lecture 5 Topic : Group Technology Group Technology
Segment B Topic:Segment B Topic: Example Example
END OF SEGMENT END OF SEGMENT
Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Lecture 5 Topic :Lecture 5 Topic : Group Technology Group Technology
Segment C Topic:Segment C Topic: Grouping – Grouping – Analysis MethodsAnalysis Methods
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 42
ADVANCED ADVANCED MANUFACTURING MANUFACTURING SYSTEMS DESIGNSYSTEMS DESIGN
Group Technology Group Technology
Grouping – Analysis MethodsGrouping – Analysis Methods
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 43
OverviewOverview• Grouping/Analysis MethodsGrouping/Analysis Methods
– Production Flow Analysis• Rank Order Clustering• Similarity Indexes
– Single Linkage– Weighted (Production Volume)
• Mathematical Programming
• NOTE: The Following Slide Materials are NOTE: The Following Slide Materials are From Singh, From Singh, Systems Approach to Systems Approach to Computer Integrated Design and Computer Integrated Design and ManufacturingManufacturing, p. 490-499., p. 490-499.
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 44
Production Flow Production Flow AnalysisAnalysis
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 45
ProductioProductionn
Flow Flow AnalysisAnalysis
Matrix
Manipulation
Row and ColumnSorting
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 46
Rank Order Clustering Rank Order Clustering (1)(1)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 47
Rank Order Clustering (2)Rank Order Clustering (2)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 48
Rank Order Clustering (3)Rank Order Clustering (3)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 49
Single Linkage Cluster Single Linkage Cluster Algorithm (1)Algorithm (1)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 50
Single Linkage Cluster Single Linkage Cluster Algorithm (2)Algorithm (2)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 51
Single Linkage Cluster Single Linkage Cluster Algorithm (3)Algorithm (3)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 52
Siefoddini and WolfeSiefoddini and Wolfe
• Considers Production Volume Considers Production Volume (Weighted Average)(Weighted Average)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 53
Exceptional Parts and Exceptional Parts and Bottleneck MachinesBottleneck Machines
• Practical Approach to Problem of Practical Approach to Problem of Costly EquipmentCostly Equipment
• Allow InterCell MovementAllow InterCell Movement• EliminationElimination
– Generate Alternate Processing Plans– Duplicate Machines– Subcontracting Operations
• Still Has InterCell Transfers
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 54
Alternate Cell Alternate Cell Configurations (SLCA)Configurations (SLCA)
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 55
Alternate Cell Alternate Cell Configuration AnalysisConfiguration Analysis
Why Why
CellCell
One?One?
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 56
Mathematical ModelsMathematical Models
• Cell Design with Known Part FamiliesCell Design with Known Part Families– Minimize Machine Investment
• Cell Design with Unknown Part Cell Design with Unknown Part FamiliesFamilies– Minimize Machine Investment– Constrains Maximum Number of Machines
in Cell
• Cell Design With Unknown Part Cell Design With Unknown Part Families, Key MachinesFamilies, Key Machines– Minimize Investment,
Movement/Backtracking
Computer Integrated Manufacturing Systems © 2000 John W. NazemetzSlide 57
Grouping EfficacyGrouping Efficacy
• Method for Evaluating Goodness of Method for Evaluating Goodness of FitFit
Advanced Manufacturing Advanced Manufacturing Systems DesignSystems Design
© 2000 © 2000 John W. NazemetzJohn W. Nazemetz
Group TechnologyGroup Technology
Discussion Topic C:Discussion Topic C: Grouping -- Grouping -- Analysis MethodsAnalysis Methods
END OF SEGMENTEND OF SEGMENT