ADVANCED MANUFACTURING SYSTEMS INDEN 5303

Report
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Cellular and Flexible
Manufacturing
Lecture 6 Topic :
Cell Formation Using
Materials Flow
Segment A Topic:
ADVANCED
MANUFACTURING
SYSTEMS DESIGN
Cellular and
Manufacturing Systems
Cell Formation Using Materials
Flow
Slide 2
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Overview
•
Cell Formation
–
Goal
•
–
Concepts
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•
•
Slide 3
Identify/Produce Part Families at Minimum
Investment in Equipment
Assume Families Exist – Identify Cells
Simultaneous Part Family and Machine Cell Formation
(Similarity, Max. Cell Size, …)
Simultaneous Part and Family Formation Using Flow
Source: Vakharia, A.J. and Wemmerlov, U., "Designing
a Cellular Manufacturing System: A Materials Flow
Approach Based on Operation Sequences," IIE
Transactions, 22(1), (1990), 84-97.
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Family Processing (1)
• Logical
– Buffers Between Machines (Process Layout)
Slide 4
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Family Processing (2)
• Physical Cells
– Linked Lines - Often No Buffers
– Backflow a Serious Problem
• Multiple Entry Points (Congestion/Contention)
• Material Handling
Slide 5
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Family Formation
Using Flow Criteria (1)
(Vakharia and Wemmerlov)
• Conventional Goals
–
–
–
–
Identify Part Families
Identify Cells
Identify Cell Equipment
Allocation of Families to Cells (or vice versa)
• Basis is Operation Sequence (Ordered Set) vs.
Routing (Unordered Set)
– Optimize
Slide 6
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Family Formation
Using Flow Criteria (2)
(Vakharia and Wemmerlov)
• Problem Decomposition
– Assumes Unlimited Capacity (Replication)
•
•
•
•
•
Zero/Single Operation Parts
Multiple Visits to Same Machine
Identical Sequences
Contained Sequences
Similarity
• Optimization
– Seek to Minimize Investment (Iterative)
Slide 7
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Data Collection
(Vakharia and Wemmerlov)
• Operation Sequence for All Parts
• Average Demand (Batches/Unit Time)
• Estimated Processing Time (Setup and
Run) for Each Batch
• Available Productive Time per Unit Time
per Machine
• Available Equipment
• Cost to Acquire Additional Equipment
Slide 8
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Preliminary Data Analysis
(1)
Vakharia and Wemmerlov)
• Notation
– i = (1, 2, …, M) -> Machine Type Index
– j = (1, 2, …, N) -> Part Index
– Orj -> OpeRation Sequence for part j
Slide 9
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Preliminary Data Analysis
(2)
Vakharia and Wemmerlov)
• Key Equipment Identification
– Equipment to Expensive to Duplicate or
Move
– X = Set of Key Machines {i, where i is “key”)
– Let there be ‘w’ such Machines
– Let M1 = M - w
– Exclude all Key Machine Operations from
ORj
– Let Modified Sequence be OR1j
Slide 10
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Preliminary Data Analysis
(3)
Vakharia and Wemmerlov)
• Single and Zero Operation Parts
– Identify all Part with Single Operation
• i.e., OR1j has only One Machine Type
– Let there be n such Parts
• OR1j has only One Key Machines
– Let there be n1 such Parts
• Remaining Parts
– N1 = N - n - n1
Slide 11
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Preliminary Data Analysis
(4)
Vakharia and Wemmerlov)
• Backtracking
– Visit Machine More than Once
• Modify Process Plan if Possible
• Separate these Parts into Two Sets
– N2 Have Multiple Visits
– N3 Do Not
– N3 = N 1 - N2
Slide 12
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Grouping
(1)
Vakharia and Wemmerlov)
• Identical Operations Sequences (GT)
– Group Parts with Identical Sequences
• Separate these Parts into Two Sets
– N4 Have Identical Sequences (from N2)
– N4 Have Identical Sequences (from N3)
• Establish Group Indexes
– OR1h, where h is part group (Multiple Visits) and
– OR1g, where g is part group (No Multiple Visits)
Slide 13
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Part Grouping
(2)
(Vakharia and Wemmerlov)
• Part Grouping
– Contained Operation Sequences (GT)
• Group Parts with “Contained” Sequences
– Group g1 is grouped with g2 if its Processing
Sequence is contained in OR2g2, (Same Operations,
Same Sequence)
» N6 Have Grouped Sequences (from N4)
» N7 Have Grouped Sequences (from N5)
Slide 14
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Candidate Cell Formation
(Vakharia and Wemmerlov)
• Use Composite Operation Sequences to Form
Cells
• Identification of Part Families
– Merge Part Groups (N7) Using Similarity Indexes
• Based on Common Machines
– Threshold Value of Similarity
– Load on Cell Capacity
• Backtracking may be Introduced -- Assess!
– Calculate Backtracking
– Based on Number, Distance
– Keep Below Threshold for Backtrack
• Repeat Until Similarity Below Threshold of Number of
Groups Left Acceptable
Slide 15
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Identification of Part Families
(Vakharia and Wemmerlov)
• Merge Single Operation Parts into Part Groups
– Add First to Cell with Largest Remaining Capacity
• Consider N6 -(Identical Backtracking Groups)
– Add to Cells if Backtracking Criteria Not Violated in
Order of Similarity (Similarity Does Not Assess
Backtracking)
• Allocate Machines to Cells to Assure Feasibility
(Capacity)
– Based on Part Demand/Load
– Based on Expected Utilization, Time Available
• Utilization < 100%, More if More Backtracking
– Any Unused Machines to a “No Load Cell”
Slide 16
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Key Machines
(Vakharia and Wemmerlov)
• Incorporate “Key” Machines into System
– Put all Key Machines into Separate Cells
– Allocate all “Only One (Key) Machine in
Routing” Parts to these Cells
– For Parts that are Processed on Multiple Key
Machines (Only), Assign to Cell Containing
Machine with Most Load/Work
Slide 17
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Final Solution
(Vakharia and Wemmerlov)
• Final Cell Design
– Assess Additional Investment in Duplicate
Equipment
• Use Ratio of Cost/Average Utilization
• Reroute Parts/Load on Machine with Highest
Ratio to One or More Similar Cells
– Maintain Capacity/Load Feasibility
– Maintain Utilization Goals
Slide 18
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Final Cell Design
(Vakharia and Wemmerlov)
• Assess Additional Investment of
Duplicate Equipment
– Use Ratio of Cost/Average Utilization
– Reroute Parts/Load on Machine with
Highest Ratio to One or More Similar Cells
• Maintain Capacity/Load Feasibility
• Maintain Utilization Goals
• Locate Cells with Shared Equipment Near One
Another
– Continue Until Investment Can be Justified
or No Parts Remain
Slide 19
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Sensitivity/Observations
(Vakharia and Wemmerlov)
Minimum Utilization Level
– Determine for Each Type of Equipment
• Remove From Cell(s), Make Cell by Self
• Maximum Cell Size
– Managerial Complexity
– Partition into Multiple Cells
– Remove (Move to Own Cell) Machines with
Highest Loads
• InterCell Movement Paths Minimized
Slide 20
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Comments
(Vakharia and Wemmerlov)
• Classic Problem Decomposition
– Seek Feasible, Not Optimal
– Seek Optimality (Practical Criteria)
• Other Family/Cell Considerations
– Alternate Routings
• Temporal (Seasonal Capacity Adjustments)
• Changing Product Mix/Stability
Slide 21
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Cellular And Flexible
Manufacturing
Lecture 5 Topic :
Cell Formation with
Material Flow
Segment A Topic:
END OF SEGMENT
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Cellular and Flexible
Manufacturing
Lecture 6 Topic :
FMS Concepts and
Design
Segment B Topic:
ADVANCED
MANUFACTURING
SYSTEMS DESIGN
Cellular and Flexible
Manufacturing Systems
FMS Concepts and Design
Slide 24
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Overview
• Cellular and Flexible Manufacturing
Systems
– Quick Review of Job, Flow, and Mass
Production Concepts (Background)
– Terminology and Definition of FMS
– Differences Between Flexible and Cellular
Manufacturing Systems
– FMS Design Concepts
Slide 25
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Background – Job Shops
• High Variability in Part Mix (Shape)
• General Purpose Equipment (Low
Utilization)
• Process Layout
• Highly Skilled Workers
• Low Volume/Repeatability of Parts
• Long Lead Times
• Little Production Planning, Information
Requirements
• Capable, Not Necessarily Efficient
Slide 26
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Background – Flow Shops
• Known/Targeted Part Mix (Shape)
• Customized General Purpose Equipment
• Highly Skilled Designers, Medium/Low Skill
Operators
• Mid-Volume/Repeatability of Parts
• Planned, Cyclic (Batch) Production
Q
QMAX
• Higher Production Planning, Information
Requirements
Slide 27
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Background – Mass
Production
• Single Product
• Customized Equipment
• Highly Skilled Designers, Low Skill
Operators
• High Volume
• Continuous Production
• Highest Production Planning,
Information Requirements
• Highly Efficient
Slide 28
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Background – Cell and
Flexible Manufacturing
• Cellular Manufacturing – Attempt to
Capture Efficiency of Mass Production
by Increasing Volume of “PseudoProducts (Part Families)”
• Flexible Manufacturing – Attempt to
Achieve Efficiency of Mass Production
While Maintaining Ability to
Economically Automate Production of
“Typical Product” (Limited Range)
Slide 29
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Terminology Used In
Computer Controlled
Manufacturing Systems
1 - Flexible Manufacturing Systems (FMS)
2 - Computer Integrated Manufacturing
System (CIMS)
3 - Variable Mission System (VMS)
4 - Variable Mission Manufacturing (VMM)
5 – Cellular Manufacturing Systems
Slide 30
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS - Definition
• An Automated, Mid-Volume, Mid-Variety
Computer Controlled Manufacturing
System Designed to Efficiently and
Effectively Process a Defined Range or
Set(s) of Parts Having Similar
Characteristics, Often Called Part
Family(ies). The System Control
Extends to Part and Tool Movement,
Part Processing, and Part Sequencing.
Slide 31
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS – Alt. Definition
• Alternate Definitions
– A Coordinated Group of Manufacturing Cells
– An Automated Job/Flow Shop
• Applicability
–
–
–
–
Process Oriented Production Systems
NC Based Production Systems
Job Shops (High Variable Product Mix)
Flow Shop (“Product Layout”)
• GT on Process Only
Slide 32
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS – “Flexible” Meanings
Meaning Dependent on Speaker, Time
– Routing Flexibility
– Part Shape(Mix) Flexibility
– Part Volume Flexibility
• Economic to Process (Set-Up)
• Ability to Produce in Volume
Slide 33
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS - Goal
• Design/Develop Highly Automated Job
Shops
– Processes are Typically Numerically
Controlled
– High Cost Equipment
– Efficient Production of Defined Shape(s)
Within Specific Size Range
• Like Job Shop, A Type of Product is Targeted
• Focus of Equipment, Tooling, etc. on the Targeted
Product Niche
Slide 34
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Flexible and Cellular
Systems
• Similarities
– Process Oriented
– Automated
– Expensive, with High Utilization a Goal
• Differences
– Cellular Based on Product Routing
– Flexible Based on Targeted Product Routing
• Overlap
– Considerable, Speaker Dependant
Slide 35
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS - Features
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•
•
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Machining Centers
Flexible Fixturing/Pallets and Tooling
Automated Material Handling
Inspection (In-line)
Scheduling/Sequencing System
Tool Management
Traffic Management
Quality Control
Maintenance
Slide 36
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS -Operational
Problems
• Part/Family Selection
– Hwang IP Model for Family Formation Based
on Tooling Needs
– Stecke and Kim Model - Extend Hwang for
Tool Magazine Capacity
• Tool Allocation
–
–
–
–
Slide 37
Bulk Exchange (Tools for Planning Horizon)
Tool Migration (Move as Batches Complete)
Resident (Tool at Machine 'Til Worn)
Sharing (Comb. Form of Migration and
Resident)
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 6 Topic :
Cellular Manufacturing
Segment B Topic:
FMS Concepts
END OF SEGMENT
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Cellular and Flexible
Manufacturing Systems
Lecture 6 Topic :
Segment C Topic:
FMS Design
Steps In The Design And
Implementation Of FMS
Systems (The C. S. Draper Lab, Inc.)
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•
•
•
•
•
Select Parts and Machines
Design Alternative FMS Configurations
Evaluate Candidate FMS Configurations
Write a Request for Proposal (RFP)
Evaluate Vendor Proposals
Prepare for, Install, and Shakedown the
FMS
• Operate the System
Slide 40
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 1: Select Parts And
Machines
• Preselect Parts and Machines Having
FMS-compatible Attributes From
Available Candidates.
• Calculate Current Production of Each
Part.
• Estimate FMS Manufacturing Cost for
Each Part.
Slide 41
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 1: Select Parts And
Machines (cont.)
• Use Either Manual Selection Methods or
a Computer Software Package (e.g.,
Part and Machine Selection (PAMS)
Program, See Volume V) to Select the
Most Economically Beneficial Parts and
Machines.
• Perform Investment Analysis to
Determine if an FMS is an Economic
Alternative
Slide 42
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 2: Design Alternative
FMS Configurations
• A. Estimate The Work Content Of The
Selected Parts
– Develop FMS Fixturing Concepts for the Selected
Parts, Minimizing the Number of Fixturings.
– Process Plan Each Part in Detail, Constrained by
the Limited Tool Capacity of an FMS and the
Effects of Using Different Machines (Roughing
and Finishing Machines, for Instance) on Overall
Accuracy and Cycle Time.
Slide 43
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 2: Design Alternative
FMS Configurations (cont.)
• A. Estimate The Work Content Of The
Selected Parts (cont.)
– Determine the Appropriate Machinability
Data for Each Material, for Each Class of
Operation (Rough Milling, Semifinish Boring,
Etc.).
– Estimate Production Requirements for Each
Part.
Slide 44
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 2: Design Alternative
FMS Configurations (cont.)
• B. Design Several Equipment
Configurations (cont.)
– Choose Specific Vendors’ Equipment in Each
Machine Class: Temper With Company
Biases ( Toward Horizontal Rather Than
Vertical Machining Centers, for Example).
– Estimate the Minimum Number of Machines
(Spindles) for Each Machine Class.
Slide 45
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 2: Design Alternative
FMS Configuration (cont.)
• B. Design Several Equipment
Configurations (cont.)
– Modify This Number of Machines to Account
for Shop and System Efficiency, Limited Tool
Storage Capacities, and Desires for Machine
Redundancy.
– Add a Material Handling System (MHS) and
Other Desired Non-Machining Processes,
Such As an Inspection Machine, to Complete
the Configuration.
Slide 46
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 2: Design Alternative
FMS Configuration (cont.)
• B. Design Several Equipment
Configurations (cont.)
– Layout the Equipment and Material
Handling System
– Develop Alternative Design Configurations
From the Original Design.
Slide 47
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 3: Evaluate Candidate
FMS Configurations
• Simulate the Operation of Each
Configuration Based on Predetermined
Scheduling, Batching, and Balancing
Rules to Provide Performance Measures
for Each Configuration.
• Improve the Configuration Designs Until
Each Provides Satisfactory Performance
Measures or Is Rejected.
Slide 48
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 3: Evaluate Candidate
FMS Configurations (cont.)
• Perform a Detailed Investment Analysis
of Each Configuration.
• Examine and Evaluate Intangibles, Such
As Flexibility, Accuracy, Etc.
• Choose the Configuration Which Best
Satisfies the Investment and Intangible
Analyses.
Slide 49
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 4: Write A Requestfor-Proposal (RFP)
• Write an RFP That Conveys Your
Findings and Desires for an FMS.
• Avoid Over Specification: Allow the FMS
Vendors to Be Creative and Competitive
in Designing an FMS for Your Situation.
Slide 50
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 5: Evaluate Vendor
Proposals
• Verify and Evaluate Vendor Proposals
Using Simulation and Economic
Analysis.
• Evaluate the Degree of Success of Each
Proposal in Satisfying Your NonQuantifiable Requirements.
• Choose the Proposal Which Best
Satisfies Your Company’s Need.
Slide 51
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 5: Evaluate Vendor
Proposals (cont.)
• Work With the Vendor to Develop
Detailed Specifications and Prices.
• Place an Order.
Slide 52
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 6: Prepare For, Install,
And Shakedown The FMS
• Select and Educate Personnel to
Operate and Maintain the FMS.
• Assess the Quality Control and
Production Control Departments’ Roles
in the Successful Implementation and
Operation of the FMS and Develop or
Augment Policies to Assure Success.
• Develop a Preventative Maintenance
Plan and Spare Parts Lists for the FMS.
Slide 53
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 6: Prepare For, Install,
And Shakedown The FMS
(cont.)
• Prepare the FMS Site.
• Assist Vendor With Installation and
Shakedown.
• Perform FMS Acceptance Tests.
Slide 54
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Step 7: Operate the
System
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Schedule Parts.
Batch Production, If Necessary.
Allocate Parts and Tools to Machines.
Balance Machine Loads.
Use a Decision Support System to
Optimize Daily Operations in the Face of
Machine Failure and Changing Part
Requirements
Slide 55
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
FMS Layout
• Circular
• U-Shaped
• Linear
– Single Row
– Double Row
• Criteria
– Minimize Material Handling
Slide 56
Computer Integrated
Manufacturing Systems
© 2000 John W. Nazemetz
Advanced Manufacturing Systems
Design
© 2000 John W. Nazemetz
Lecture 6 Topic :
Cellular Manufacturing
Segment C Topic:
FMS Design
END OF SEGMENT

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