Next Generation Factory Layouts

Saifallah Benjaafar, University of Minnesota

Shahrukh Irani, Ohio State University

Sunderesh Heragu, Rensselaer Polytechnic Institute

Flexible Modular Reconfigurable Agile

Characteristics

High product variety Product demand volatility Low production volumes Short product lifecycles

Needs

Functional versus Cellular Layouts

Functional layout Cellular layout

Material handling inefficiency Scheduling complexity Vulnerability to changes in product mix/routings/volumes Prohibitive re-layout costs

Limitations of functionallayouts

Rapid obsolescence Workload unbalances Limited flexibility Resource duplication

Limitations of cellularlayouts

Distributed Layouts

Functional layout Partially distributed layout

Fully distributed layout

Effective hedging against future fluctuation in product mix, volume and routings Efficient material handling Flexible workload allocation Rapid formation of virtual cells

Advantages

Design Procedure for Distributed Layouts

Department dis-aggregation

procedure

Distribution of demand scenariosProduct process routingsProduct unit transfer loadsTravel distances

Flow allocation procedure

Layout design procedure

Layouts are constructed as a network of basic modules. Each module is a group of machines in a portion of the overall facility that has a flow pattern characteristic of a traditional layout.

Modular Layouts

No single prevailing layout configurations can individually describe the complex material flow network in a multi-product manufacturing facility. Modules can be added and removed as needed. It captures the efficiency of each layout configurations without the associated limitations.

Motivation

Layout Modules

(a) Flowline Module

(c) Cell Module

C

D

E

B

A

A B

C

G H

D

E F

(b) Branched Flowline Module

(d) Machining Center Module

A

B

C

D

E

(f) Patterned Flow Module

A+B+C

(e) Functional Layout Module

A

B C D

E

A B C D E

Example Modular Layout

5.01 5.02 5.03 5.04 5.05 5.06 5.07

2.01

2.07

2.06

3.07

3.087.03 7.02 7.01

7.04 7.05 3.04

6.01

1.03 1.04 1.05

1.02 1.01

Flowline for PHOTO

Functional Layout for ETCH

Functional Layout for

FILM Department

Flowline for BACKEND

Cell for ETCH, IMPLANT and PHOTO

Flowlines for DIFF

Functional Layout for

ETCH, FILM and PHOTO

2.08 2.09 2.10

Flowline for ETCH

5.05

4.01

2.02

2.05

3.01

3.04

3.06

5.02

5.03

5.04

3.02

3.05

String Matching-Based Design Procedure

Extract commonsub-strings

Identify predominantproduct routings

Aggregate common sub-strings and form preliminary modulesModule selection

and layout design

Layouts are physically reconfigured (by moving resources and reconfiguring the material handling system) on short notice due to change in product mix or production volumes.

Reconfigurable Layouts

In many industries, fabrication and assembly workstations are light and can be easily relocated. Newer processing technologies permit light weight equipment. Light weight equipment could be mounted on wheels and easily moved along suitably designed tracks embedded in the shop-floor.

Motivation

As a result, a layout could be changed several time a year!

Re-Layout Design Procedure

Design Data + New Product Design + New Processes Selected

Production Data

+ Expected Volume + Changed Product Mix

Revised Material Flow Matrices / Adjacency Matrices

Current Facility Layout Relocation Costs

Mat

eria

l Han

dlin

g C

osts

Facility Layout Design

Output + Machine Locations + Material Flow Plan

Layouts are designed with agility-based criteria, such as cycle time, work-in-process, and production throughput.

Agile Layouts

A Queueing-Based Layout Design Procedure

Material handling system

Processing departments

Input buffer Output buffer

4

3

2

1

Empty trip from destination of previous delivery to origin of current request

Full trip from the origin of current request to its destination department

Congestion is affected by: travel distances (empty and full travel) travel distance variability number and capacity of material handling devices dispatching policies processing time distributions utilization of processing departments

Queueing Effects

Reducing full travel does not always improve performance. Full travel- optimal layouts can be congestion-infeasible. Congestion is affected by both the mean and variance of travel times. Congestion is affected by non-material handling factors.

Queueing Effects

Although most factories of the future will need customized layout solutions, the produced layouts must be robust, adaptable, and agile. This project is exploring novel ways of achieving this goal.

Summary