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Communication Links among VariousDesign Functions

Product

Design

Process

Design

Operation

Design

Layout

Design

Objectives for Facilities Layout

q To minimize the investment required in new

equipment.q To minimize the time required for production.

q To utilize existing space most efficiently.

q To provide for the convenience, safety, and comfortof the employees.

q To maintain a flexible arrangement.

q To minimize the materials handling cost.

q To facilitate the manufacturing process.

q To facilitate the organizational structure.

Layout problems develop as

q The change in the product design.

q The addition or deletion of a product.

q Significant increase or decrease in the demand.

q The change in the process design.

q The replacement of one or more pieces ofequipment.

q The adoption of new safety standards.

q Organizational changes within the company.

q A decision to build a new plant.

Layout problems develop gradually by

q bottlenecks

q crowded conditions

q unexplainable delays and idle time

q backtracking

q excessive temporary storage space

q obstacles to materials flow

q failure to meet schedules

q a high ratio of material handling time to productiontime

Factors affecting the flow pattern

q external transportation facilities

q number of parts in product

q number of operations on each part

q sequence of operations on each part

q number of subassemblies

q number of units to be produced

q necessary flow between work areas

q amount and shape of space available

q influence of processes

Factors affecting the flow pattern(continued)

q Types of flow patterns

q product vs. process type of layout

q location of service areas

q production department locations

q special requirements of departments

q material storage

q desired flexibility

q the building

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Types of flow patterns

q

Straight line flowq L-shaped flow

q U-shaped flow

q S flow

q Circular flow

q Serpentine flow

q Vertical flow patterns

Activity Relationship Chart

q

A: Absolutely necessaryq E: Especially important

q I: Important

q O: Ordinary importance

q U: Unimportant

q X: Undesirable

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Types of layouts

q

Fixed product layout(ex) large airplanes, ships and rockets

q Product layout(ex) assembly lines, transfer lines

q Group layout

q Process layout

Fixed Product Layout - advantages

q Material movement is reduced.

q Promotes job enlargement.

q Continuity of operations and responsibilityresults from team.

q Highly flexible (accommodating changes inproduct design, product mix, and productionvolume).

q Scheduling is possible to achieve minimumtotal production time.

Fixed Product Layout - limitations

q Increased movement of personnel andequipment.

q Equipment duplication may occur.

q Higher skill requirements for personnel.

q General supervision required.

q Cumbersome and costly positioning ofmaterial and machinery.

q Low equipment utilization.

Product Layout - advantages

q Smooth and logical flow lines result.

q Small WIP result.

q

Total production time per unit is short.q Material handling is reduced.

q Training is simple, short, and inexpensive.

q Simple production planning and controlsystems are possible.

q Less space is occupied by work in transit andfor temporary storage.

Product Layout - limitations

q A breakdown of one machine may lead to acomplete stoppage of the line

q A change in product design may requiremajor alterations in the layout.

q The pace of production is determined by theslowest machine.

q Supervision is general.

q Comparatively high investment is required.

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Group Layout - advantages

q Increased machine utilization.

q Team attitude and job enlargement tend tooccur.

q Compromise between product layout andprocess layout, with associated advantages.

q Supports the use of general-purposeequipment.

q Shorter travel distances and smoother flowlines than for process layout.

Group layout - limitations

q General supervision required.

q Higher skill levels required of employees thanfor product layout.

q Compromise between product layout andprocess layout, with associated limitations.

q Depends on balanced material flow throughthe cell.

q Lower machine utilization than for processlayout.

Process Layout - advantages

q Better utilization of machines can result.

q A high degree of flexibility exists relative toequipment or manpower allocation.

q Comparatively low investment in machines isrequired.

q The diversity of tasks offers a moreinteresting and satisfying occupation for theoperator.

q Specialized supervision is possible.

Process Layout - limitations

q Material handling is more expensive.

q Production planning and control systems aremore involved.

q Total production time is usually longer.

q Comparatively large amounts of WIP result.

q Space and capital are tied up by WIP.

q Higher grades of skill are required.

Assignment model algorithm

1. Locate the smallest number in row 1 and subtract it from all theentries in row 1. Repeat for all rows.

2. Locate the smallest number in column 1 and subtract it from allthe entries in column 1. Repeat for all columns.

3. If it is possible to make a zero cost assignment, then do it. Thatwill be the optimal solution. If not, go to 4.

4. Determine the maximum number of zero cost assignments.

5. Choose the smallest uncovered number and do the following:

a. subtract it from all other uncovered number.

b. add it to the numbers where the lines cross.

c. return to 3.

Computerized Layout Techniques

q Construction algorithms

q PLANET

q

CORELAPq ALDEP

q Improvement algorithms

q CRAFT

q COFAD

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Measures of Distance

q

Euclidean distance

q Rectilinear distance

( ) ( )x a y b + 2 2

| | | |x a y b +

The single-facility rectilinear distancelocation problem

q Assume that n existing facilities are located atpoints:(a1, b1), (a2, b2), (an, bn)

q Locate a new facility among n existingfacilities.

q The goal is to find values of x and y tominimize:f(x, y) = wi (|x - ai| +|y - bi|)

q The weights allow different traffic rates.