CONWIP Systems CONWIP – Constant work-in-process

Slides:

Advertisements

Similar presentations

CONWIP (A pull alternative to kanban principle)

Advertisements

Process Design and Analysis

PROCESS DESIGN AND ANALYSIS Chapter Eleven Copyright © 2014 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin.

© The McGraw-Hill Companies, Inc., 1998 Irwin/McGraw-Hill Module 11 Operations Scheduling Chapter 16 (pp ) Work Center and definitions  Objectives.

11–1. 11–2 Chapter Eleven Copyright © 2014 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin.

CHAPTER FIFTEEN JUST-IN-TIME SYSTEMS Chapter 15 Just-In-Time Systems.

Lean Supply Chains Chapter Fourteen McGraw-Hill/Irwin

Operations Scheduling

DOM 102: Principles of Operations Management Operations Scheduling

23–1. 23–2 Chapter Twenty-Three Copyright © 2014 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin.

Short-Term Scheduling

1 Simulation Modeling and Analysis Session 13 Simulation Optimization.

MODELING AND ANALYSIS OF MANUFACTURING SYSTEMS Session 6 SCHEDULING E

Modeling and Analysis of Manufacturing Systems Session 2 QUEUEING MODELS January 2001.

Customer Service in Pull Production Systems Mark L. SPEARMAN Presented By: Ahu SOYLU.

Push and Pull Systems: Lecture 12

CHAPTER 14 Just-In-Time Systems.

Lean operations and JIT

Irwin/McGraw-Hill 1 Process Analysis Terms Process: Is any part of an organization that takes inputs and transforms them into outputs. Cycle Time: Is the.

1 Chapter 15 Scheduling. 2 Scheduling: Establishing the timing of the use of equipment, facilities and human activities in an organization Answering “when”

CHAPTER 19 Scheduling Operations Management, Eighth Edition, by William J. Stevenson Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.

JIT and Lean Operations

1 Chapter 7 Dynamic Job Shops Advantages/Disadvantages Planning, Control and Scheduling Open Queuing Network Model.

Operations Scheduling. Scheduling in a Process-Focused Environment.

Operations Management Contemporary Concepts and Cases Chapter Thirteen Scheduling Operations Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights.

McGraw-Hill/Irwin © 2006 The McGraw-Hill Companies, Inc., All Rights Reserved. 1.

Chapter 6 Process Analysis.

1 © The McGraw-Hill Companies, Inc., 2004 Introduction (from Chase) Process Analysis.

1-1 1 McGraw-Hill/Irwin ©2009 The McGraw-Hill Companies, All Rights Reserved.

CONWIP (A pull alternative to kanban principle)

15-1Scheduling William J. Stevenson Operations Management 8 th edition.

OM4-1Aggregate Planning Chapter 14. OM4-2Aggregate Planning Planning Horizon Aggregate planning: Intermediate-range capacity planning, usually covering.

CONWIP (A pull alternative to kanban principle) Main resources : Mark Spearman, David Woodruff and Wallace Hopp Northwestern University, Evanson, Illinois,

15-1Scheduling William J. Stevenson Operations Management 8 th edition.

Supply Chain Management Location of Inventory General Idea: Store as little inventory as possible while still being responsive to customer. Approaches:

Managing Kanban Systems Two primary control parameters for a Kanban System. Kanban container size (n i ) Number of Kanbans (k i )

1 1 Slide Short – Term Scheduling Professor Ahmadi.

Chapter 12 Just-in-Time and Lean Manufacturing. What is JIT? (Just-in-Time) An operations philosophy involving many techniques for improving the effectiveness.

Scheduling Process and Production Management.

Topics To Be Covered 1. Tasks of a Shop Control Manager.

Chapter 17 Scheduling. Management 3620Chapter 17 Schedule17-2 Overview of Production Planning Hierarchy Capacity Planning 1. Facility size 2. Equipment.

Process Characteristics

1 Manufacturing Operations Scheduling B2 [ ] B2 [ ] E5 [ E5 [ P9 [---] P9 [---] D1 [ D1 [

Scheduling. Scheduling: The allocation of resources over time to accomplish specific tasks. Demand scheduling: A type of scheduling whereby customers.

McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. 15 Lean Operations.

1 Control of Production-Inventory Systems with Multiple Echelons.

Scheduling for Low-volume Operations

Scheduling Seminar exercises Process and Production Management.

CONWIP (A pull alternative to kanban principle)

Lot-Sizing and Lead Time Performance in a Manufacturing Cell Article from Interfaces (1987) by U. Karmarkar, S. Kekre, S. Kekre, and S. Freeman Illustrates.

Aggregate Planning. Session Break Up Aggregate Planning Master Production Schedule.

Production Activity Control

The Revolution of Just-In-Time (JIT) and Lean Manufacturing

Lean operations and JIT

Chapter 5 Process Analysis. Chapter 5 Process Analysis.

PRODUCTION ACTIVITY CONTROL (PAC)

An introduction to Factory Physics

Process Design and Analysis

Constraint Management

The Revolution of Just-In-Time (JIT) and Lean Manufacturing

Performance Measures, Capacity Planning & Scheduling

Production Activity Control

PRODUCTION ACTIVITY CONTROL (PAC)

Chapter 5 Process Analysis.

Kanban Replenishment for All Types of Industries

8 Job Sequencing & Operations Scheduling CHAPTER Arranged by

Process Analysis “If you cannot describe what you are doing as a process, you do not know what you are doing.” W.E. Deming.

Sequencing Sequencing: Determine the order in which jobs at a work center will be processed. Workstation: An area where one person works, usually with.

Presentation transcript:

CONWIP Systems CONWIP – Constant work-in-process Similar to Kanban system in goal of maintaining constant level of work-in-process. Differs from Kanban in that all WIP is aggregated and treated as a whole.

CONWIP Systems CONWIP Facility Demand Backlog List CONWIP Facility Demand As a batch of jobs is completed and leaves the facility, a signal is sent to release the next order. The order is the next batch of jobs on the backlog list. The backlog list is based on the forecast of customer demand and low finished goods inventory.

CONWIP Systems Insert fig 7.11 The amount of WIP in the system (N) is the control parameter of interest for CONWIP. Too large an N results in long lead times and excess WIP. Too small an N results in idle workstations and reduced output.

CONWIP Systems Insert fig 7.11 Technique to determine N: Identify bottleneck station. Gradually increase N (release faster than withdrawals occur) until input queue before bottleneck is rarely empty.

CONWIP Systems Comparison to Kanban Systems: CONWIP systems immediately react to increases in customer demand. As customers increase the rate at which jobs are withdrawn, the high demand jobs are released into the system. CONWIP systems do not need the setup and maintenance of Kanban cards and containers for each part type. CONWIP systems react well for highly variable part mix demand while maintaining relatively constant levels of inventory.

CONWIP Systems Comparison to Kanban Systems cont: CONWIP systems are more complex in that they require a means for maintaining the backlog list. CONWIP systems require ample storage space before machines because although WIP as a whole is constant, WIP is not controlled within each workcenter. Over time, as demand changes, unwanted WIP may “clog up” the system and count towards the overall WIP, thus making the system less responsive. To resolve, periodically “cleanse” the system of the unused WIP.

CONWIP Systems Developing/Prioritizing Backlog List: Earliest due date Minimum slack time (due date – E(lead time)) Target finished-goods inventory levels Insert table 7.6

CONWIP Systems Rough performance measures if processing times are constant: Let: tj = average batch processing time at workstation j. M = number of work centers. If parts visit all work centers, then: is cumulative processing time at all stations. If there are N jobs in the system and M workcenters, then on average there are N/M jobs at each workcenter. Therefore the time, Tj spent at a job center is: And the time, T, spent in the system is: