MULTIPLE ACTIVITY and MULTIPLE ACTIVITY and MATERIAL HANDLING MATERIAL HANDLING

STUDIESSTUDIES

Rodger Koppa, P.E., Ph.D.Rodger Koppa, P.E., Ph.D.

Industrial and Systems Industrial and Systems EngineeringEngineering

Multiple Activity StudyMultiple Activity Study

DefinitionMultiple Activity Study is the creation of a

description that brings together the contributions of more than one operator and/or equipment to complete a task, often linked by a common timeline.

Multiple Activity ChartA chart on which the activities of more than

one subject (worker, machine, or item of equipment) are each recorded on a common time scale to show their interrelationship.

Introduction to Work Study (4th Ed) G. Kanawaty (Ed) International Labour Office, Geneva, Switzerland

1992

Comments on Multiple Activity Charting

Can have both workers and equipment on same timeline

Use shading or crosshatching to discriminate “productive” from “unproductive” time

Times are observed from video recordings, actual observation (time each component separately during cycle)

SWAG for preliminary analysis

Task Description vs Task Analysis

Task description is systematic identification or recording of operations (including times) at a level adequate for purpose at hand

Task Analysis fulfills the purpose of: Job description Task improvement Workplace layout Training Standards for cost and/or wage setting

Microtask Description Two-handed Process Chart Activities of worker’s hands or limbs

recorded in their relationship to each other Use same symbols as in macro charts:

Operation O

Temporary Storage D

Transport →

Hold (“storage”) ▼

Example of Microtask Example of Microtask DescriptionDescription

Comments on 2-handed Process Comments on 2-handed Process ChartsCharts

Leave space for sketch/photo of layoutLeave space for sketch/photo of layout

Chart one hand at a timeChart one hand at a time

Video recording almost a must unless you Video recording almost a must unless you can have worker repeat many timescan have worker repeat many times

Record actions on same line only when Record actions on same line only when the occur at same time the occur at same time

Operational Sequence Operational Sequence DiagramingDiagraming

• Multiple workers and/or equipmentMultiple workers and/or equipment• Uses standard process chart symbolsUses standard process chart symbols• Can be written along vertical Can be written along vertical

timeline (sequence and approximate timeline (sequence and approximate time period)time period)

Pictorial VariantPictorial Variant

• Operational Sequence Diagrams may Operational Sequence Diagrams may use pictorial elementsuse pictorial elements

• Purpose may be to present ideas to Purpose may be to present ideas to higher management not familiar higher management not familiar with process chart conventionswith process chart conventions

• Works well for tasks that cover a lot Works well for tasks that cover a lot of territory with multiple people and of territory with multiple people and equipmentequipment

Material Handling (Travel) Material Handling (Travel) StudiesStudies

Worker/Material HandlingWorker/Material Handling

Movement of workers and/or Movement of workers and/or materials around the work areamaterials around the work area

Two approachesTwo approaches String DiagramString Diagram Travel Chart Travel Chart

String DiagramString Diagram

Scaled layout of work areaScaled layout of work area Each worker or piece of material gets its Each worker or piece of material gets its

own diagram or color thread (3 or less) own diagram or color thread (3 or less) Pins and threads (or computer analog)Pins and threads (or computer analog) Multiple cycles or other specified period Multiple cycles or other specified period

of operation of operation Each translation from one station to Each translation from one station to

another takes one threadanother takes one thread

Example of String Diagram Example of String Diagram StudyStudy

Comments on String Comments on String DiagramsDiagrams

Compelling graphicCompelling graphic Complicated operations can make Complicated operations can make

the diagram a rat’s nestthe diagram a rat’s nest Time-consuming to constructTime-consuming to construct Use Travel Charting when many Use Travel Charting when many

movements and complex paths are movements and complex paths are encounteredencountered

Travel Charting A tabular record for presenting quantitative

data about movement of workers, material, and equipment between stations over a given period of time

Matrix is always square, FROM along top and TO along side

Each column and row is assigned to a station – 6 stations would require 6 x 6 matrix

Accompanied by layout sketch showing spatial relationship of stations

Travel Chart Procedure Use data sheet to record movements

Square for each from-to movement Tallies for each time that movement

happens Fill in chart with √ or just l for each

movement Get marginal totals Compare FROM and TO marginal

totals

Travel Chart Analysis

Rank order stations from busiest to least busy

High-ranked stations should be close to each other to minimize travel times

On example, 2,5,9 highest frequency FROM or TO

Busiest route 5-2-9 cell frequencies (5-2) = 5; (2-9)=6

Weighted Travel ChartWeighted Travel Chart

Same concept as plain travel chartSame concept as plain travel chart Translations weighted by Translations weighted by

weight or volume carried (quantity)weight or volume carried (quantity) Total recorded in cells of chartTotal recorded in cells of chart

Rank order by marginal quantity Rank order by marginal quantity High loads between stations mean High loads between stations mean

short distances, conveyor belts, crane, short distances, conveyor belts, crane, etc.etc.

ResourcesResources

Resources for this lecture include:Resources for this lecture include:

Kanawaty, G. (Ed) Kanawaty, G. (Ed) Inroduction to Work Inroduction to Work Study (4Study (4thth Ed.) Ed.) Geneva: International Geneva: International Labour Office 1992Labour Office 1992

Groover, M.P. Groover, M.P. Work Systems and the Work Systems and the Methods, measurement, and Methods, measurement, and Management of WorkManagement of Work Pearson- Pearson-Prentice Hall 2007Prentice Hall 2007