eind 2303: work design and industrial...

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Islamic University of Gaza - Palestine

Department of Industrial Engineering

EIND 2303: Work Design and Industrial Ergonomics


Learning Outcomes

After careful studying this chapter You should be able to

• Define the term productivity & Labor productivity,

• Explain the total task time (productive time versus non-

productive time),

• Discuss the causes of non-productive activities,

• Differentiate between manual work and Human-machine-

systems & automated System,

• Explain the differences between repetitive vs. non-

repetitive tasks

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Productivity

• The level of output of a given process relative to the level of input

(output/input)

• Process can refer to

– Individual production or service operations

– Can be used in the context of a national economy

• Productivity is an important metric in work systems because Improving

productivity means

– saving scarce natural and human made resources

– worker compensation can be increased without increasing the

costs of products and services they produce

• Products and services at lower prices for consumers which improves

standard of living


Labor Productivity

• The most common productivity measure is labor productivity,defined by the following ratio:

LPR =

where LPR = labor productivity ratio, WU = work units ofoutput, LH = labor hours of input

• The definition of output depends on the process underconsideration

– Steel industry : ton

– Automobile industry: number of cars

– Labor hour (aggregate unit)

• Makes it possible to make comparisions accross different industries

)(

)(

InputLH

OutputWU

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Labor Factor in Productivity

• Labor itself does not contribute much to improving productivity

• More important factors:

– Capital - substitution of machines for human labor

• Investing an automated production m/c to replace a manually

operated m/c

– Technology - fundamental change in the way some activity or

function is accomplished

• It is more than using a m/c in place of a human worker

• A technologically more developed m/c replaces the previous one.


Examples of Technology Changes

Horse-drawn carts

Steam locomotive

Telephone operator

Manually operated milling

machine

Railroad trains

Diesel locomotive

Dial phone

Numerically controlled (NC)

milling machine

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Increasing Productivity

• Important gains in productivity are more likely to be made

– By the introduction of capital and technology in a work

process than by attempting to get more work in less time out

of the workers

• For example, in construction industry, mortar in mixers pumped

into molds rather than workers mixing by shovels


Productive Work Content

A given task performed by a worker can be considered to

consist of

• Basic productive work content

– Theoretical minimum amount of work required to accomplish

the task

• Excess nonproductive activities

– Extra physical and mental actions of worker

– Do not add value to the task

– Do not facilitate the productive work content

– Take time

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Excess Nonproductive Activities

Can be classified into three categories:

• Excessive activities due to poor design of product or service

• Excessive activities caused by inefficient methods, poor

workplace layout, and interruptions

• Excessive activities caused by the human factor


Allocation of Total Task Time

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Poor Design of Product or Service

• Products with more parts than necessary, causing excess

assembly time

• Product proliferation (more choices for the customer than

necessary)

• Frequent design changes

• Quality standards too stringent


Inefficient Methods, Layout, Etc.

• Inefficient layout that increases material handling activities

• Inefficient workplace layout that increases hand, arm, and

body motions

• Methods that include unnecessary work elements that waste

time

• Long setup times in batch production

• Frequent equipment breakdowns

• Workers waiting for work

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The Human Factor

• Absenteeism

• Tardiness

• Workers spending too much time on socializing

• Workers deliberately working slowly

• Inadequate training of workers

• Industrial accidents caused by human error

• Hazardous materials that cause occupational illnesses


Manual Work & Worker-Machine Systems

1. Manual Work Systems

2. Worker-Machine Systems

3. Automated Work Systems

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Three Categories of Work Systems

1. Manual work system– Worker performs one or more tasks without the aid of

powered tools (e.g. hammers, screwdrivers, shovels)

2. Worker-machine system– Human worker operates powered equipment (e.g. a

machine tool)

• Physical effort (less)

• Machine power(more)


Three Categories of Work Systems

3. Automated work system– Process performed without the direct participation of a

human worker

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Manual Work System


Worker-Machine System

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Automated System


Some Definitions

• Work unit – the object that is processed by the work system

– Work piece being machined (production work)

– Material being moved (logistics work)

– Customer in a store (service work)

– Product being designed (knowledge work)

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Manual Work Systems

• Most basic form of work in which human body is used to accomplish some physical task without an external source of power

• With or without hand tools

– Even if hand tools are used, the power to operate them is derived from the strength and stamina of a human worker

– Hairbrush vs hair dryer

• Of course other human faculties are also required, such as hand-eye coordination and mental effort


Pure Manual Work

Involves only the physical and mental capabilities of

the human worker without machines or tools.

– Material handler moving cartons in a warehouse

– Workers loading furniture into a moving van without

the use of dollies

– Office worker filing documents

– Assembly worker snap-fitting two parts together

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Manual Work with Hand Tools

• Manual tasks are commonly augmented by use of handtools.

• Tool is a device for making changes to objects (formallywork units) such as cutting, grinding, striking, squeezing

– Scissor, screwdriver, shovel

• Tools can also be used for measurement and/or analysispurposes

• Workholder to grasp or poisiton work units


Manual Work with Hand Tools

Examples:

• Machinist filing a part

• Assembly worker using screwdriver

• Painter using paintbrush to paint door trim

• QC inspector using micrometer to measure the diameter

of a shaft

• Material handling worker using a dolly to move furniture

• Office worker writing with a pen

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Repetitive vs. Nonrepetitive Tasks

Non-repetitive TaskRepetitive Task

•Work cycle takes a long time

•Work cycles are not similar

•Work cycle is relatively short

(usually a few minutes or less)

•High degree of similarity from

one cycle to the next

In either case, the task can be divided into work elements that consist of

logical groupings of motions


Automated Work Systems

Automation is the technology by which a process or

procedure is accomplished without human assistance

• Implemented using a program of instructions combined

with a control system that executes the instructions

• Power is required to drive the process and operate the

control system

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Levels of Automated Systems

• Semiautomated machine

– Performs a portion of the work cycle under

some form of program control

– Human worker tends the machine for the remainder of the cycle, by loading and unloading it

– Operator must be present every cycle

• Fully automated machine

– Operates for extended periods of time with no

human attention


Automated

robotic

spot

welding

cell (photo

courtesy of

Ford Motor

Company)

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End of Chapter

eind 2303: work design and industrial...

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