Second Semester 2009 – 2010 Assistant Professor Abed...

Islamic University of Gaza - Palestine

Department of Industrial Engineering

EIND 2303: Work Design and Industrial Ergonomics

Second Semester 2009 – 2010Assistant Professor Abed Schokry


ERGONOMICS

Greek Words “Ergon = work, NOMOS --> = laws”

The Laws to be Observed at Work

Ergonomics means Study of Work Laws


What is Ergonomics?

New Definition: Science of fitting workplace conditions and job

demands to the capabilities of the working population


What is Ergonomics?

Ergonomics is the laws of work that define the limits to human capability.


Ergonomics is the science of improving employee performance and well-being in relation to the

job tasks, equipment, andthe environment.

Ergonomics is…» a continuous improvement

effort to design the workplace for what people do well.

What is Ergonomics?


Ergonomics is fitting the job to the person

What is Ergonomics?


“ Fitting the job to the worker”, not the worker to the job

Use your brain, not your back,Work smarter, not harder,Fix the job, not the worker,

What is Ergonomics?


ERGONOMICS and DISCIPLINES

• Ergonomics is a Multi-Disciplinary Science

• Ergonomics is also an Inter-Disciplinary Science


Applications of Ergonomics

AnatomyOrthopedicsPhysiologyMedicine

PsychologySociology

Industrial EngineeringBio-Engineering

Systems EngineeringSafety EngineeringMilitary Engineering

Computer-Aided Design

AnthropometryBiomechanics

Work PhysiologyIndustrial Hygiene

ManagementLabor Relations


Human Factors Engineering

Human Factors Engineering

Physical and mental work capacity Industrial design Fatigue Work place designBody forces, strength and posture Product designBody sizes Furniture designThermal comfort/ heat stress/cold stress Machine designVision VentilationHearing LightingPerception AcousticsInformation processing Engineering controlDecision making (Chemical & Physical)Performance and efficiency Building orientationAdaptation and rehabilitation MaintenanceBehavior & social relations


Ergonomics

Ergonomics means literally the study or measurement of WorkIn addition to work as labor for monetary gain, work also includes

SportsLeisure activitiesDomestic workEducation and trainingHealth and social services


Ergonomics considers human operators variability

An automobile design has to consider– Range of physical size and strengths of users– Seats are comfortable– Controls readily identifiable and within easy reach– Clear visibility front and back– Easily read internal instruments– Ease of entry and way out


AIMS OF ERGONOMICS

Ensure that human needs for safe and efficient working are met in the design of work systemTo design

Appliances Technical Systems Tasks

In such a way to improve Human Safety Health Comfort and PerformanceProductivity


Benefits of ergonomics

ProductivityProduct qualitySafetyHealthReliabilityJob satisfactionPersonal development


Basic aims of ergonomics

Efficiency in purposeful activityTo achieve desired result without

WasteErrorDamage to persons

Working situation in harmony with the activities of the worker


Difficulties in achieving the aims of ergonomics

Human operator is flexible and adaptableLarge individual differencesObvious differences: --> Physical size, strengthNot obvious differences --> Culture, style, level of skill

Thus a systematic approach and theory are necessary. There should be measurable objectives to be checked and remedial action taken. Adetailed study of the science of ergonomics provides these approaches and theories


DEFINITIONS OF ERGONOMICS

Ergonomics is a way of improving working conditions and reducingillness at work

Ergonomics attempts to ‘Fit the Job to the Man’ rather than ‘Fit the Man to the Job’ and select the right person to the job

Ergonomics is concerned with the design of systems in which people carry out work

Ergonomics optimizes Efficiency, Health, Safety and Comfort of people through better designs of products and work places


DEFINITIONS OF ERGONOMICS

Ergonomics is a way of improving working conditions and reducingillness at work

Ergonomics attempts to ‘Fit the Job to the Man’ rather than ‘Fit the Man to the Job’ and select the right person to the job

Ergonomics is concerned with the design of systems in which people carry out work

Ergonomics optimizes Efficiency, Health, Safety and Comfort of people through better designs of products and work places


DEFINITIONS OF ERGONOMICS (1)

Ergonomics is:“Higher productivity and a better place to work”“The science that saves both lives and dollars”“Human engineering where the goal is to optimize worker well being and productivity”“A way of thinking about and planning work so that it suits the capabilities and needs of the people”


ERGONOMICS is

Ergonomics is a solution finding method for questions like these:How can human body dimensions be applied to car seat design?What is the proper height for kitchen counters?How can traffic lights be programmed for optimal urban traffic flow throughout the day?How can stereo receiver displays and controls be coded to effectively define their respective functions?How can the material and design of swim suits for competition beimproved for minimal water resistance?How should computer software and screens work and look best to fit human cognitive capabilities?


• Force

• Repetition

• uncomfortable Postures

• fixed postures

Ergonomic Risk Factors

• Vibration

• Extreme temperatures

• Pressure and stress at work

• Forceful movements


Historical Figures Related to Work

• Industrial Revolution (1770’s)

– James Watt• steam engine

– Henry Maudslay• screw-cutting lathe

• (Factories)

– Machines started to replace workers– Produce more quickly and accurately– Specialization of labor – Use of large numbers of unskilled labors who works long hours for

low pay (including women & children)


Historical Figures Related to Work (1)

Interchangeable parts manufacture

– Eli Whitney (1765-1825)• produces 10000 muskets for the US government• Standard parts• Special tools, fixtures etc.• Unique products replaces custom-fabricate products

• Mass production (assembly line)

– Henry Ford (1863-1947)•Model T for less than $500 in 1916

Scientific management (late 1800s)

– Frederick W. Taylor (1856-1915)

•Father of scientific management


• Scientific management (late 1800s)

– Frank (1868-1924) & Lillian Gilbreth (1878-1972)• Father (mother) of motion study

– All works are composed of basic motion elements (therbligs)

– There is one best method to perform a certain task– Cheaper by the Dozen

– Motion study (finding the best method to perform a task)– Time study to establish work standards for a job– Use of standards in industry– Labor incentives (bonus payments for higher outputs)– Use of data collection, record keeping, cost accounting

– The objective is to improve the (labor) productivity

Historical Figures Related to Work (2)


Frederic W. Taylor (1856-1915)

• Founder of the ‘Scientific Management’ term

• Emphasized on:– Increasing throughput– Reducing manufacturing costs– As a result, increasing workers’ salaries

• Tools (how to do the above): – Divide the task into small elements– Separate the non-required from the required elements– Setting standards: time, quality, methods.– Specialization: training for a specific job


Who is a human operator?

Skilled professional using a complex machine in an artificial environment

Customer who has purchased a new equipmentChild sitting in a classroomDisabled person in a wheel chair


DISCIPLINES IN ERGONOMICS

ERGONOMICS

PSYCHOLOGY-COGNITIVE

-WORK

-SOCIAL

ANATOMY-ANTHROPOMETRY

-BIOMECHANICS

PHYSIOLOGY-ENVIRONMENTAL

-WORK


ERGONOMICS


-WORK

-SOCIAL


-BIOMECHANICS


-WORK

TOXICOLOGY

ENVRONMENTAL MEDICINE

INDUSTRIAL DESIGN

OPERATIONS RESEARCH

ENGINEERING

MANAGEMENTLAWECONOMICS



ERGONOMICS


-WORK

-SOCIAL


-BIOMECHANICS


-WORK

ARTIFICIAL INTELIGENCE MANUFACTURING

WORK ORGANIZATIONSYSTEMS DESIGN

TOXICOLOGY

ENVRONMENTAL MEDICINE

INDUSTRIAL DESIGN

OPERATIONS RESEARCH

ENGINEERING

MANAGEMENTLAWECONOMICS



PROFESSIONS & ERGONOMICS

ERGONOMICS

Safety

OfficerCivil

Engineer

Mechanical

Engineer

Architect

Industrial

DesignerSocial

Psychologist

Ind. Medical

Officer

Physiotherapist

Industrial

Nurse

Occupational

Health Officer


Ergonomic needs in a workplace

Physical work environmentThermal comfortNoise and vibration controlAdequate and proper lighting

Chemical environmentControl of pollutionGeneral and exhaust ventilation

Work physiologyControl excessive physical loadAvoid physical and muscular fatigueAdequate rest pausesArrangement of static and dynamic work


Anthropometry (Body sizes)

Designs to fit body sizes of usersAppropriate working levelsAdequate work spaceAvoid overcrowding of machines and workers

Occupational Biomechanics

Appropriate work postures (sitting, standing)Safe load lifting and carrying techniquesAdopt proper techniques in manual materials handling

Ergonomic needs in a workplace (1)


Psychological aspects

Avoid perceptual and mental loads and fatigueAppropriate design of displays and controlAppropriate conditions for Vigilance tasksAvoid human error and stressJob motivation and satisfaction

Social psychologyPractice good relationship among employees and between employer and employee



Macro ergonomicsSuitable working hours , intervals, holidays, leaveAppropriate shift schedulesWelfare facilitiesJob rotation and incentives schemesFair salary structure, Good administrative structureGood work organization schemesFringe benefits (housing, transport, sports)Labor union facilitiesTraining and educationPromotional prospects



Safety and Ergonomics

Good housekeepingPerformance feedback

Systems ergonomicsSystems groups in problem solving and development workParticipative ergonomicsUser centered designs



HOW CAN ERGONOMICS CONTRIBUTE TO TECHNOLOGY DEVELOPMENT IN INDUSTRIALLY DEVELOPING COUNTRIES

By adaptation of technology of the westBy improving working conditions through ergonomics interventionsBy developing traditional methodsIn acquiring modern technologyIn modifying techniquesNeed Training and Education in Ergonomics


Ergonomic contributions to development in industrially developing countries

Research on basic data needsPromote special abilitiesRefine simple methodsMore appropriate “experts”Action learning (Learning by doing, not imitating)Better supported education and researchRe-conceptualize standard setting


Work

• Is our primary means of livelihood

• Serves an important economic function in the global world of commerce

• Creates opportunities for social interactions and friendships

• Provides the products and services that sustain and improve our standard of living


The Nature of Work

• Work is an activity in which one exerts physical and mental effort to accomplish a given task or perform a duty

• Task or duty has some useful objective

• Worker applies skills and knowledge for successful completion

• The activity has commercial value

• The worker is compensated


The Questions Employers Need Answers For:

Developing new productsIncreasing production capacityIdentifying equipment and labor needsIdentifying costs of manufacturing productsDetermining work hours and shift schedulesDefining job productivity and quality standardsSetting compensation levelsIdentifying skills for tasks Structuring tasks into jobsIncreasing the available workforce by reducing problematic tasks


Work (Physics Definition)

• The displacement (distance) that an object moves in a certain direction multiplied by the force acting on the object in the same direction.

– W = F . d (Newton-meter)

• Units of measurement: – Newton-meters (N-m) in the International System of Units (metric system)

– Foot-pounds (ft-lb) in U.S. customary units

• Work is more than muscular applications.

• Combination of physical and cognitive work.


The Pyramidal Structure of Work

• Work consists of tasks

• Tasks consist of work elements

• Work elements consist of basic motion elements


Task

• An amount of work that is assigned to a worker or for which a worker is responsible

• Repetitive task – as in mass production– Time required = 30 seconds to several minutes

• Non-repetitive task – performed periodically, infrequently, or only once– Time required usually much longer than for repetitive task


Work Element

• A series of work activities that are logically grouped together because they have a unified function in the task

• Example: assembling a component to a base part using several nuts and bolts

• Required time = six seconds or longer


Basic Motion Elements

• Examples:– Reaching for an object– Grasping the object– Moving the object– Walking – Eye movement

• A work element consists of multiple basic motion elements

• Less than a second


Pyramidal Structure of Work

• Extended to a worker’s career


Importance of Time

• In many human activities, “time is of the essence”– In sports– In daily living– In business and industry– In work


Importance of Time in Business and Industry

• New product introduction • Product cost (reduced time means reduced labor costs)• Delivery time • Overnight delivery• Competitive bidding (proposals should be submitted by a

specific date)• Production scheduling (being on time)


Importance of Time in Work

• Time is the most frequently used measure of work (not Newton-meter)

– How many minutes or hours are required to perform a given task? • Most workers are paid by the time they work

– Hourly wage rate – Salary– Time=Money

• Workers must arrive at work on time– Otherwise his/her absence may handicap the rest of the team

• Labor and staffing requirements computed in units of time– Aggeragate unit


Work System Defined

• As a physical entity, a work system is a system consisting of humans, information, and equipment designed to perform useful work

• Results of the useful work contributes to the production of a product or delivery of a service

• Examples:– Worker operating a machine tool in a factory– An assembly line consists of a dozen of workers at seperate work

stations along a moving conveyor– Parcel service agent driving a delivery truck to make customer

deliveries– Designer working at a CAD workstation– A receptionist answering incoming phone calls


A Work System as a Physical Entity


Work System Defined (1)

• As a field of professional practice, work systems include:

• Work methods - analysis and design of tasks and jobs involving human work activity

– Operations analysis & methods engineering

• Work measurement – analysis of a task to determine the time that should be allowed to perform the task– Time study

• Product costs• Worker performance• Worker requirements• Standard time

– How long it takes to accomplish a given work– (Time=Money)


Work System Defined (2)

• As a field of professional practice, work systems include(cont.)

• Work management – organizational and administrative functions that must be accomplished to achieve high productivity and effective supervision of workers– Organizing workers– Motivating workers– Evaluating jobs– Evaluating performances– Compensating workers (labor wages)


Comparisons: Industries and Workers

• It is convinient to group occupations into the following four groups although there are more types of occupations

1. Production workers – Making products– Manufacturing, construction, agriculture

2. Logistics workers – Moving materials, products, people– Transportation, distribution, material handling


• It is convinient to group occupations into the following four groups although there are more types of occupations (cont.)

3. Service workers – Providing service, applying existing information knowledge,

communicate– Banking, retail, government, health care

4. Knowledge workers – Creating knowledge, solving problems, managing– Management, engineering, legal, consulting, education

Comparisons: Industries and Workers (1)


Comparison of Work Characteristics

Physical activities Cognitive activities


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 of output, LH = labor hours of input

• The definition of output depends on the process under consideration– Steel industry : ton– Automobile industry: number of cars– Labor hour (aggregate unit)

• Makes it possible to make comparisions accross different industries

LHWU


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


Increasing Productivity

• Important to recognize 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


Measuring Productivity

• Not as easy as it seems because of the following problems:– Nonhomogeneous output units (Polo vs Golf)– Multiple input factors

• Labor, capital, technology, materials, energy

• Productivity comparisons are not easy for:– Price and cost changes due to economic forces and these

effect the worth of the output• If prices decrease but costs increase productivity may be

less meaningful


Labor Productivity Index

Measure that compares output/input ratio from one year to the next

LPI =

where LPI = labor productivity index, LPRt = labor productivity ratio for period t, and LPRb = labor productivity ratio for base period

b

t

LPRLPR


Example: Productivity Measurement

• During the base year in a small steel mill, 326,000 tons of steel were produced using 203,000 labor hours. In the next year, the output was 341,000 tons using 246,000 labor hours. Determine: (a) the labor productivity ratio for the base year, (b) the labor productivity ratio for the second year, and (c) the productivity index for the second year.


Example: Solution

(a) In the base year, LPR = 326,000 / 203,000= 1.606 tons per labor hour

(b) In the second year, LPR = 341,000 / 246,000= 1.386 tons per labor hour

(c) Productivity index for the second yearLPI = 1.386 / 1.606 = 0.863

• Comment: No matter how it’s measured, productivity went down in the second year.


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


Excess Nonproductive Activities

Can be classified into three categories:

• Excess activities due to poor design of product or service• Excess activities caused by inefficient methods, poor

workplace layout, and interruptions• Excessive activities cause by the human factor


Allocation of Total Task Time


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


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 Systems2. Worker-Machine Systems3. Automated Work Systems4. Determining Worker and Machine Requirements5. Machine Clusters


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)

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

worker


Manual Work System


Worker-Machine System


Automated System


Some Definitions

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

– Workpiece being machined (production work)– Material being moved (logistics work)– Customer in a store (service work)– Product being designed (knowledge work)

• Unit operations – tasks and processes that are treated as being independent of other work activities

– As opposed to sequential operations (sequence of operations required to manufacture a product or deliver a service)


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– Dealer at a casino table dealing cards– Office worker filing documents– Assembly worker snap-fitting two parts together


Manual Work with Hand Tools

• Manual tasks are commonly augmented by use of hand tools.

• Tool is a device for making changes to objects (formally work units) such as cutting, grinding,striking, sequeezing – Scissor, screwdriver, shovel

• Tools can also be used for measurement and/or analysis purposes

• Workholder to grasp or poisiton work units


Manual Work with Hand Tools

• 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


Repetitive vs. Nonrepetitive Tasks

• Repetitive Task– Work cycle is relatively short (usually a few minutes or less)– High degree of similarity from one cycle to the next

• Nonrepetitive Task– Work cycle takes a long time– Work cycles are not similar

• In either case, the task can be divided into work elements that consist of logical groupings of motions


Cycle Time Analysis

• Cycle time Tc

where Tek= time of work element k, where k is used to identify the work elements (min) ne = number of work elements into which a cycle is divided.

1

en

c ekk

T T=

= ∑


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Second Semester 2009 – 2010 Assistant Professor Abed...

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