2.008 Manufacturing Systems 2.008 -Spring 2004

Outline Manufacturing Systems Types of Plant Layouts Production Rates Design and Operations 2.008 -Spring 2004

Manufacture Market Research Conceptual Design Design for Manufacture Unit Manufacturing Processes Assembly and Joining Factory, Systems & Enterprise 2.008 -Spring 2004

What is mfg systems? 2.008 -Spring 2004

Time spectrum of Typical Activities in a Manufacturing Organization Seconds Period Activity 108 Decade Plant design, Machine Selection, 107 Year System Simulation Process design: CAD 106 Month Catalogs Select manufacturing methods Week 105 Day Factory Operation 104 Ship-Receive Hour Transport Inventory 103 102 Minute Part handling 101 Load/Unload Assembly 1 Second .1 Machine control CNC-DNC .01 Adaptive control Intelligent machines .001 Millisecond Process control 2.008 -Spring 2004

How Man, Machine, and Material Spend Time in the Factory People Materials Machines Value-added Waste "Waste": waiting for materials, watching machine running, producing defects, looking for tools, fixing machine breakdowns, producing unnecessary items, etc “Waste”: transportation, storage, inspect on and rework "Waste": unnecessary movement of machine, setup time, machine breakdown, unproductive maintenance, producing defective products, producing products when not needed, etc. 2.008 -Spring 2004

Disruptions/Variation (Random Events) Machine failure Set-up change Operator absence Starvation/Blockage Demand change 2.008 -Spring 2004

Types of Plant Layout Job Shop Project Shop Flow Line Transfer Line Cellular System 2.008 -Spring 2004

Job Shop Raw Material Ready part A D C Machines/Resources are grouped according to the process they perform 2.008 -Spring 2004

Project Shop Machines/Resources are brought to and removed from stationary part as required A C B D Raw material/ Ready part 2.008 -Spring 2004

Flow Line and Transfer Line Raw Material Ready part B C D F G Machines/Resources are grouped in lines according to the processes sequence of part(s) 2.008 -Spring 2004

Cellular System Raw Material Ready part B C E A D F G Machines/Resources are grouped according to the processes required for part families 2.008 -Spring 2004

Production Quantity and Plant Layout Project Shop Job Shop Cellular System Flow Line 1 10 100 1,000 10,000 100,000 Quantity 2.008 -Spring 2004

Production Rates Case I: One machine Everything works M 2.008 -Spring 2004

Production Rates (cont’d) Case II: One machine Machine breaks down (disruption) Everything else works M 2.008 -Spring 2004

Production Rates (cont’d) Case III: Many machines No machine breaks down No buffers M1 M2 Mi Mk 2.008 -Spring 2004

Production Rates (cont’d) Case IV: Many machines (same operation time) No machine breaks down No buffers M1 M2 Mi Mk 2.008 -Spring 2004

Production Rates (cont’d) Case V: Many machines (same operation time) Machine breaks down No buffers M1 M2 Mi Mk 2.008 -Spring 2004

Production Rates (cont’d) Case VI: Many machines and buffers in between Machine breaks down M1 M2 Mi Mk B1 B2 Bk-1 Mk-1 2.008 -Spring 2004

Production Rates (cont’d) Production rate increases if: Increase the rate of the slowest machine Reduce the disruptions Introduce “buffers” Introduce in-process control 2.008 -Spring 2004

Disruptions (Random Events) Machine failure Set-up change Operator absence Starvation/Blockage 2.008 -Spring 2004

Waiting Underutilization Idleness Inventory 2.008 -Spring 2004

Inventory/Work-in-Process (WIP) It costs money It gets damaged It becomes obsolete It shrinks It increases lead time 2.008 -Spring 2004

Cycle Time and Lead Time Order Supply Plant Supplier Customer 2.008 -Spring 2004

Cycle Time “Cycle Time” ．The time a part spends in the system Little’s Law: L = λw L: average inventory λ: average production rate w: average cycle time 2.008 -Spring 2004

Cycle Time (cont’d) Example: Operation time = 1, One-piece operation Production rate = 1 Cycle time = 5 Inventory = 5 M1 M2 M3 M5 M4 2.008 -Spring 2004

Cycle Time Batch Production 1. Operation time: 3 minutes Batch (Lot) size: 1000 Cycle time = 1,000*3 + 1,000*3 + 1,000*3 = 9,000min Op1 Op2 Op3 2.008 -Spring 2004

Cycle Time One-Piece Production 2. Operation time = 3 minutes Cycle time = 1,000*3 + 2*3 = 3,006 minutes Op1 Op2 Op3 2.008 -Spring 2004

Cycle Time and Lead Time Order Supply Plant Supplier Customer 2.008 -Spring 2004

Systems Design and Operation Cycle time < Lead time Lumpiness Information contents 2.008 -Spring 2004

Lumpy Demand Forging X Forging Y Steel Z Wrench A Wrench B Wrench C Wrench D D 1 P 5 D 6 P 15 D 3 P 10 D 7 P 25 Forging X Forging Y D 20 15 P 25 D 35 P 50 Steel Z D 75 25 50 2.008 -Spring 2004

Typical Design Guidelines Leveling Balancing Single-piece flow Low materials handling Low setup time Smaller lot size Low WIP Faster feedback 2.008 -Spring 2004

Plant Operations Push (MRP, ERP, etc.) vs. Pull (JIT) Batch vs. One-piece 2.008 -Spring 2004