Advanced Manufacturing Systems Design 2000 John W

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Advanced Manufacturing Systems Design © 2000 John W. Nazemetz Cellular and Flexible Manufacturing Lecture 6 Topic : Cell Formation Using Materials Flow Segment A Topic: Computer Integrated Manufacturing Systems

Overview • Cell Formation – Goal • – Concepts • • • 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 (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 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 -> Ope. Ration 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 M 1 = M - w – Exclude all Key Machine Operations from ORj – Let Modified Sequence be OR 1 j 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. , OR 1 j has only One Machine Type – Let there be n such Parts • OR 1 j has only One Key Machines – Let there be n 1 such Parts • Remaining Parts – N 1 = N - n 1 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 – N 2 Have Multiple Visits – N 3 Do Not – N 3 = N 1 - N 2 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 – N 4 Have Identical Sequences (from N 2) – N 4 Have Identical Sequences (from N 3) • Establish Group Indexes – OR 1 h, where h is part group (Multiple Visits) and – OR 1 g, 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 g 1 is grouped with g 2 if its Processing Sequence is contained in OR 2 g 2, (Same Operations, Same Sequence) » N 6 Have Grouped Sequences (from N 4) » N 7 Have Grouped Sequences (from N 5) 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 (N 7) 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 N 6 -(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 • Inter. Cell 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 Computer Integrated Manufacturing Systems

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 “Pseudo. Products (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 • • • 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

Steps In The Design And Implementation Of FMS Systems (The C. S. Draper Lab, Inc. ) • • • 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 Non. Quantifiable 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 • • • 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