6 Ergonomics,Works Study - Method, Motion and Time Study POM Hand Out 6

ERGONOMICS, WORKS STUDY-METHOD, MOTION AND TIME STUDY

Human Factors in Job Design

1. Consideration of man and machine in job2. Design and Adaptation of machine to man3. Ergonomics4. Working Environment5. Worker safety

Employees are the most valuable assets of an organization. They have intrinsic value which no machine can replace. They are alive to the situation with diversity of skills, emotions and levels of performance which machines do not have. Jobs are work activities performed by employees in an organization to achieve its goal. Job design specifies what, when, where and How of the task to be performed.Therefore it is crucial that for achieving the organizational goal, such job designs should be clear, specific and to be communicated and well understood. In any work environment, it is important to (1) Respect human dignity and equality of all employees.(2) Provide employees with jobs that encourage self actualization through development of their knowledge, values and job related skills.Job design

- Job objectives- its relation to work methods, - work measurement and - Job satisfaction

Job design –Job is the work activity performed by employee with or without the aid of machines, in an organization to achieve its goal. Job design is the what, when, where and how of such task to be performed. It specifies the content of the task, skill and training required to perform and the degree of specialization in terms of academic knowledge or experience or expertise.Job design is a continuous effort to organize tasks, duties and responsibilities into unit of work to achieve the goal. It integrates work content, skills, knowledge and abilities required for a job. Job design is critical to an organization’s survival. While the organization aims at improving productivity and reducing the cost and input ,

• the job should not be too • boring ,monotonous , tiring , • too hard or demanding , • repetitive

Dr. M KOTEESWARAN MBA II SEM POM 2012 Hand Out - 6 Page 55


which may generate dissatisfaction among the workers. Employees’ motivation and satisfaction are crucial to retain their services and expertise and improve the productivity. Taylor’s principles of scientific management and the behavioral school emphasized on human aspects in production and organization and their behavioral impacts on organizations. The environmental factors such as

• noise, • safety, • pollution, • ventilation, • industrial occupational hazards, • illumination etc are some of the issues addressed in job design.

Thus the objectives of job design are(1) To create a work system that is productive and effective;(2) Technically feasible – the person assigned the job should have the knowledge, skill, training, ability, experience and information; Selection of process and equipment and tools and machines.(3)Economically feasible – the cost should be reasonable (4) Behavioral feasibility – Job should provide motivation and satisfaction; promote social interaction, group reaction, attitudes etcThus the objectives of job design areThe jobs in an organization arise out of priorities it receives from market environment, capacities available to satisfy the needs. Thus the objectives of job design areThe resulting job design dictates work methods which in turn require some work measurement and produce some job satisfaction.





Economies of

production

Products to produce &

processes to use

Resources and

Technical capability

Environment

MarketSocial- Legal

OrganizationalGoals &

Principles

Organizational capabilities

and capacity

Individual &

Group- values

Job Design- Goals

- Standards

Individual Group

– Abilities- Skills


Individual &

Group- values

Job Design- Goals

- Standards

Individual Group

– Abilities- Skills

Job Satisfaction

Work Methods

- Job engineeringMotion Economy

Work measurement


Effects of specialization As a worker does a job over a period and repeatedly, he becomes more familiar, more proficient and more experienced that he is able to do it faster and better. Effects of specialization However, his expertise, knowledge and skill are narrowed down to the specialized area/task that doing the same job may become dissatisfying. This dissatisfaction may lead to lower productivity. Hence, most fundamental concern of job design relates to the degree of specialization that should be designed or built in the job.Effects of specialization Advantages

1. Lower education 2. Fewer skills required 3. Labour readily available 4. Easier / faster training5. Lower wage cost 6. High output / time period

Disadvantages 1. Repetitive, boring, monotonous2. Lower level of employee satisfaction3. Higher cost of absenteeism, turnover4. Reduced opportunity for improvement5. More imbalance of tasks.6. More difficult to control quality.JOB Motivational

TechniquesEffect on Job/ Individual

1. Variety in job a) Job enlargementb) Job rotation

Additional tasksRotation among different tasks

2. Time on Job a) Flexi timeb) 4 day weekc) Job sharing

Flexibility in arrival/departureFewer days/ longer working Hrs/dayJob shared between two workers.

3. Psychology a) Job enrichment Hertzberg – motivational factors- Achievement- Recognition- work itself- Advancement- GrowthHackman – meaningfulness and responsibility. Task identification-



Jobs are a set of activities performed by an employee in a period of time with or without the aid of machines to produce goods or service to achieve the objective of the organization. Jobs are to be designed carefully to ensure productivity at a high level and avoidance of waste of man and machine idle item. While doing so, it should also avoid creation of dissatisfaction in the worker.Every job can be considered to be a set of work activities forming a cycle. The cycles repeat during the period of time. Hence, the productivity of a single cycle is the typical productivity of that workstation comprising the man and machine.In a job, it may not be possible to engage the man or machine throughout the cycle time. The job design attempts to increase the utilization of man and machine in a cycle. This is done by using a chart recording the time consumed by each divisible activity in performing a job by man and machine. The possibilities are:Man Engaged Idle Engaged Idle Thing

EngagedTime Idle

Machine Idle Engaged Engaged Idle

The man-machine utilization has undergone great changes1. Pre automates time and 2. After Automates1. Pre automates time: Man was actually engaged in a machine whenever machine was working. Thus the man’s idle time was very little. The machine idle time was slightly more like setting / loading etc.2. After Automates:With the introduction of automates and continuous operation machines and robots and multi-activity machines like turret and multi drills etc, the machine utilization has increased while man’s idle time per work station had increased. Hence man is assigned more stations simultaneously or conveyor system us used like in assembly line – auto TV, computers etc.

Dr. M KOTEESWARAN MBA II SEM POM 2012 Hand Out - 6 9


ErgonomicsAs the industrial culture developed and progressed, it had become clear, important and necessary to investigate and study deep into the human behavior in work situation. Soon it had developed into a separate body of knowledge called human factors engineering or ergonomics. This is also called biomechanics or engineering psychology different from industrial psychology. Ergonomics means study of work and its environment in order to achieve maximum efficiency.One of the major aspects of ergonomics in job design is to make the machines and working environment more suitable and adaptable to the man working there.Job design takes into consideration the physical and mental effects of work on the workers which are taken care of while designing, positioning of machine and equipment.

Ergonomics is the study of how human being physically interfaces with their work. It provides guidelines in adjusting technology for material utilization of human potential under favorable environment and social conditions.It builds in industrial safety, comfort, effectiveness and quality of work life. Ergonomics is a multi disciplinary study and application of the branches of engineering, psychology, economics, work study and social sciences.

Ergonomics is concerned with

Dr. M KOTEESWARAN MBA II SEM POM 2012 Hand Out - 6 0

Time Man Turret Drilling

1. Loading xxxxxx

xxxxxx

2. Loading yyyyy

yyyyy

yyyyy

3. zzzzzz

zzzzzz

Zzzzzz

zzzzzzz

zzzzzzz

4.

5. Unloading Xxxxxx

xxxxxx

6. Loading

7. yyyyy

Yyyyy

yyyyy

8. Unloading Xxxxxx

xxxxxx

9. Loading

10. UnloadingLoading

Zzzzzz

zzzzzz


(1) Man – Machine interface in physical terms – I generation.(2) Man – environment interface – II generation.(3) User – System interface in technology(4) Man – Machine – environment – organization interface – III generation.

Adaptation of machines to manWhether an organization is involved in production of goods or services, man is interfaced with machine and environment as a system. Since human parts like height, length of arms or fingers, etc cannot be redesigned to suit the machine; it is the machine and environment which have to be re designed to suit the men working.It is the machine and environment which can be modified or redesigned to suit or create a congenial, comfortable and safe work place.To operate a machine, the worker must be able to understand the operating conditions and procedure and reach various controls. Unwanted motions, pictures and wasteful actions will increase the fatigue of the worker. Ergonomics aims to avoid such situations by making the machines to adapt to man. For example, the locations of controls in a machine may be within easy reach of certain arm length and not so in others. It is the location which also helps the speed of the reach and accuracy of the adjustment.People vary in height, weight, strength, skill and sizes of their limbs and organs. The anthropometrics data on the dimensions of various parts of human body have been collected to serve the basis for design of tools and systems. The data on reach, range of motion, speed of response, sitting height, working height and other variables have been tabulated for use on workstation design. For example, the principle that strength of the system is that of its weakest link is adopted in ergonomics. In a workplace, the reach to operate an equipment neither should nor be more than that of the person having the shortest reach. All controls should be clearly visible and easily accessible. The switches should have the same off/on position through out, gauge should point in the same direction. Levers and handles must be of proper size and smooth and easy to operate without effort.Similarly, the environmental conditions influence the productivity. These include temperature, humidity, noise levels, lighting, ventilation, colour scheme, colour of the machines, cleanliness, orderliness, workstation itself.

1. Improving workflow2. Reducing repetitive nature of work3. Illumination levels, direction, intensity4. Colour scheme5. Appropriately rest area; grouping people etc are other conditions.

Work study



Work study thus is the body of knowledge concerned with the analysis of work methods and equipment was in performing a job. It is concerned with developing the optimum method and standardisation of methods.Work study thus is the body of knowledge concerned with the analysis of work methods and equipment was in performing a job. It is concerned with developing the optimum method and standardisation of methods.Method Study is concerned with finding the facts about a situation and after critically examining the facts, developing a better method of doing that work.Time Study is concerned with setting time standards for a qualified worker to perform a job at a defined level of performance. Method study obviously must precede time Study.The scope of work study is to simplify the work and measure the work required to be done to work simplification and work measurement.The steps involves in work study are briefly:

Method Study Work Measurement



Work studyTime study

Work measurementMethod study

Work Simplification

Time studySynthetic methodAnalytical estimating methodPredetermined motion time systemActive sampling

Operations process chartFlow process chartTwo handed process chartTravel chartSimultaneous motion cycle chartMultiple activity chartMan-machine chartFlow diagramString diagramCycle graph

Simplify workDevelop best method

Establish work content of job

Establish std. time


1. Select the work /Job /process / operation to be studied.

1. Same

2. Record the present method in detail to justify using it.

2. Record necessary effective/ineffective time in the existing.

3. Process charts Operation Flow Motion charts

3. Examine each ineffective time element to eliminate.

4. Examine critically - Purpose - Place - Sequence - Person Means

4. Define method to be use

5. Break down job into elements 5. Break down job into elements

6. Define new method. 6. Measure quantity of work - Time study - Synthesis - Analytical study

7. Install & maintain the new method for higher productivity.

7. Estimate normal time & add relevant allowances to determine standard time

1. Select2. Record3. Examine4. Develop

5. Measure 6. Define 7. Install 8. Maintain.Benefits of work study

1. Improved layout of office, working areas of factories.2. Improved design of plant & equipment.3. Improved use of materials, equipment & manpower.4. Most effective material handling.5. Improved work flow.6. Standardisation of methods & procedures.7. Improved safety.8. Better working conditions.9. Increased productivity.10. Reduced manufacturing cost.11. Better manpower and capacity planning.12. Better employee morale and job satisfaction.



The objectives / uses of work measurement1. Work standards reduce the effort involved in a job by minimising unnecessary movements.2. It identifies inefficient methods and replaces them with efficient methods.3. It helps schedule operations.4. It provides information about time required to perform a particular task.5. Improves machine utilisation by reducing idle time.6. Compares efficiencies of different methods.7. Provide benchmarks to evaluate workers performances.8. Improves Man wing and control of activities.9. More efficient man wing of plant.10. Reliable indices for later performance, cost control and sound incentive schemes.

Recording techniques The recording technique used in method study are broadly

a) Charts b) Diagrams c) Photographic aids.Charts Information recorded

1. Outline process Only principal operations And inspection process

2. Flow process Activities of men, material, equipment are analysed into five events.

1. Operation 2. Transport 3. Inspection4. Temporary storage/delay D5. Storage

3. Two handed process Movement of two hands or limbs of the operator right/left.

4. Multiple Activity Simultaneous/interrelated activities of operators and/or machines on a common time scale

5. Simultaneous Motion Cycle (SIMO) Movement of body members of the operator (hand/s, finger/s, head, eyes, leg/s, hip) expresses as therbligs on a common time scale.

Recording techniques Diagrams Models

1.Flow diagram Path of men, materials, equipment on a scale model.



2.String diagram as above, using a string to trace the path.

3.Photographic Aidsa) Cycle graph

b) Chrono Cycle graph

1.Movement of hand obtained by photographic plate to light Emitting from small bulbs attached to operator's fingers.2. Cycle graph using flash lights.

Examine StepExamine step is carried out in three stagesa) Primaryb) Secondaryc) Alternatives.Recording techniques

Principles of Motion EconomyIn the process of examination phase of method study when alternative are critically examined certain principles are applied. These are called principles of motion economy.These considerations are know as ergonomic consideration at work. These fall in three broad categories:


Examination of Primary Stage Secondary Alternatives

1. Purpose What is the purpose of the event?Why is it necessary

What else should be done?

What should be done?

2. Place Where does it take place? Why these?

Where else could it be done?

Where should be done?

3. Sequence When does it occur? Why then?

Where else? When?

4. Person Who comes out? Why that person?

Who else? Who?

5. Means How is the purpose achieved? Why that particular way?

How else? How?


a) Related to use of human body.b) Related to arrangement of the work place.c) Related to design of tools and equipment.Principles related to use of human body: 1. Two hands should begin and end their motion at the same time.2. Both hands should not be idle at the same time except during 1st period.3. Motions of arms should be made in opposite symmetrical directions and should be made simultaneously.4. Momentum should be employed to assist the worker.5. Ballistic movements are faster, easier and more accurate.6. Rhythm is essential.Work Place Related: 1. Definite and fixed place for tools and materials.2. Tools, Materials and controls should be close to the operator.3. Gravity feed bins and containers should be used to deliver materials.4. Loop deliveries must be used where possible.5. Material and tools must be placed to permit best sequence.6. Height of the workplace should help alternate sitting and standing easily.

Design of tools and equipment: 1. Hands should be free by proper jigs and fixtures.2. Two or more tools to be considered.3. Tools and materials to be pre-positioned4. Load should be equally distributed among fingers.5. Handles of tools should offer as much surface contact to the hand as possible.

Motion Study. Motion study is to eliminate wasteful, unnecessary, inefficient and ill directed motion performed by worker in the course of his work. Motion Study.It is to improve productivity and reduce fatigue. It is a valuable technique originally formed by Gilberths. It makes analysis of minute operation in a job like movement of eyes searching for an object, locating it, and finding it which is very rapid measured in 1/2000 of a minute called THERBLIG reverse spelling of GILBRETH, filmed as a motion picture for later analysis. Time is counted as winks equal to 1/2000 of a minute.

Work Measurement The Purpose of Time StudyStop watch Time StudyPerformance RatingAllowance FactorsStandard TimeWork Sampling TechniqueMicro motion study is done by taking motion picture, preparing SIMO chart, breaking job cycle with the bligs to measure basic body motions of worker consisting of



1.When motion begins2. Nature of motion3. When motion ends.

The bligs are well defined and have notation like:-1. Search (Sr)2. Select (St)3. Grasp G4. Transport Empty (TE)5. Transport Loaded (TL)6. Hold (H)7. Release Load (RL)8. Position (P)9. Inspect (I)10. Assemble (A)11. Dis Assemble (DA)12. Use (U)13. Delay (D)14. Unavoidable Delay (UD)15. Available Delay (AD)16. Plan (P)17. Rest (R )18. Find (F)Wink count begin

Lefthand descrip tion

Therblig Time in winks

Total time

in winks

Time in winks

Therblig Right hand description

100

110

130

150

180

220

Search for bolt

Select bolt

Reach bolt

Grasp

Carry

Position

Sr 10

St 20

TE 20

G 30

TL 40

P 40

10

30

50

80

120

15

15

10

20

40

100

115

130

140

160

200

Search for worker

Select worker

Reach for worker

Grasp

Carry

Position

Time Study

The objectives / uses of work measurement:

1. Work standards reduce the effort involved in a job by minimising unnecessary movements.2. It identifies inefficient methods and replaces them with efficient methods.



3. It helps schedule operations.4. It provides information about time required to perform a particular task.5. Improves machine utilisation by reducing idle time.6. Compares efficiencies of different methods.7. Provide benchmarks to evaluate workers performances.8. Improves Man wing and control of activities.9. More efficient man wing of plant.10. Reliable indices for later performance, cost control and sound incentive schemes.

The prerequisites for work standards

1. Work should be measurable.2. It should have a definite start and finish time.3. It should have clearly defined steps.4. The output of the work studied should be large enough to justify the expenses of WM studies.

Technique Source of Time Timing Role of Analysis

1. Time Study Stop watchDirect observation record time for several cycles of task judge and record pace

2. Standard Data TableDefine task in small common elements. Look up time value in std. Data Task

3. Pre determined Motion Times systems

TableDefine task in basic body motions. Look up value in Basic Motion Tasks

4. Work Sampling

% of study period for a given task / No. of units produced.

Direct observation randomly checks employee status. Keep tallies of emp. Activities and pace. Get production count.

5. Historical Analysis Past records of actual take times

Determine arithmetic mean and/or useful statistics

6. Work Sampling % of study period buy at a given task / No. of units produced.

Direct observation randomly checks employee status. Keep tallies of emp. Activities and pace. Get production count.

The work sampling procedure.



Work sampling study includes:

1. Determine the objective of the study/select the job.2. Define the states of activities to be observed.3. Inform the workers to be observed.4. Delineate the operations and prepare list of workers activities.5. Prepare a schedule of random observation times:-(i) % of time being denotes to each phase of activity = P(ii) Setting of accuracy limits = e(max. Error %) and z std. Dev.(iii) Estimation of no. of observations required.(iv) Selection of the length of the study period.6. Observe, rate and record worker activities / schedule.

7. Record starting, stopping times and no. of acceptable units completed during the period.

8. Compute normal time NT = CT*PRCT=Cycle time= Total time/ No.of cycles9. Compute Standard Time = ST = NT *AF• where AF = 1/(1 -% Allowance) • ST = NT / (1-% Allowance) • AF = Allowance Factors.

• Time study is part of work study. • It is a technique used to measure WORK. • It identifies time standards for a particular job performed by a competent

worker under standard conditions. • The time is recorded using a time watch or by studying the video chip of the

job execution.Prerequisites for time study are:

1. The selected job should be standardised

2. It should use standard tools and materials.

3. The worker where performance is to be observed for setting time standard should be competent. He should be qualified with required physical attributes, intelligence, education, skill and knowledge to carry out the work on hand to satisfactory standards of safety, quantity and quality.

Allowances in Time Study

The normal time is the time required to perform a job by an average worker. It is not the std. Time since a worker cannot perform the job continuously nonstop for a variety of reasons. A worker has to attend to calls of nature, may be tired and fatigued, there may be avoidable and unavoidable delays in delivery of materials, machine break down may occur. Hence, it is useless to arrive at normal time as it will not reflect the reality. The purpose of time study is to fix time to perform a job over a loop period till some changes occur requiring change of timings. So far calculating standard time allowances for these factors are considered. The amount



of time elapsing during these delays is estimated and the available fraction of time for the job is calculated. The allowances are depressed as a % of total allowed time. Therefore the standard time is the normal time divided by the fractions for the actual time.Various types of allowances are:

1.Relaxation.2.Contingency3.Process.4.Special.5.Periodic Activity.

• Relaxation Allowance: is for personal affairs of the worker like – fatigue due to exertion, posture, concentration, working condition, attending to calls of nature, drinking water, attending calls etc. It varies from 10 to 20% of normal time.

• Contingency Allowance: is for in frequent non repetitive activities such as getting materials, tools from stores, sharpening tools etc. It may be above 5% of normal time.

• Process Allowance: is the idle time by worker when automatic machine processes the job. The worker is forced to be idle during part of the work cycle.

• Interference Allowance: is allowed to a worker when he looks after 2 or 3 machines. One machine may be idle when the worker is working on another for a short while.

Ratings and allowances in Time study

Periodic activity allowance is that time used for setting up a tool on the m/c. If all the allowances amount to 15% of normal time:

Standard Time = Normal Time / ( 1 – 0.15).The steps involved in Time Study

1.Job identification and division.2.Observation3.Pace rating the worker.4.Computing the normal time.5.Allowance.6.Computing the standard time.1. Job Identification and division:

• Job that is to be studied is selected.• It should be standard in terms of equipment and materials.• Divide the job into convenient elemental tasks.• Each elemental task should be identifiable.



• It should have starting and ending points, such that time taken for the element can be accurately measured.

2. Observation:

• Performance of the worker is closely watched.• Observations are noted in a preprinted study data sheet, using stopwatch.• Several cycles of each elemental task are timed.• This is to avoid the effects of early and late readings, delays and

interruptions.3. Pace Rating the worker:

• When workers are aware that their performance is recorded, then behave differently – nervous, resentful, afraid, slow down pace. So observations are recorded for several cycles and for several workers. Based on these observations, each worker is rated as a % of normal worker.

4. Computing normal time:

• Normal Time = Average cycle time x worker rating.

5. Allowances:

• Normal Time is not the standard time required to perform the task.• Hence allowances such as• Contingency (unavoidable delays)• Interference• Relation (for personal needs) are considered6. Computing Standard Time:

• Std. Time is the actual time taken by an average worker to perform a task. It is the ratio of normal time and the avoidable fraction of time for the worker to actually perform the task after allowances.

Cycle time 2.50 min. performance rating 95% Allowances 10%

Normal Time = 2.50 x 0.95 = 2.375.Standard Time= 2.375 / (1 – 0.10)

= 2.375 / 0.90 = 2.63.

The frequency distribution of Times observed by a Time Study Minutes 20 21 22 23Frequency 15 10 10 5

Find the Standard time for an operating with rating of 110% and allowance of 15%.

Cycle time = (20x15)+(21x10)+(22x10)+(23x5)/4= 300 + 210 + 220 + 115 / 40= 845 / 40 = 21.125

Normal time = 21.125 x 1.10 = 23.24Std. Time = 23.24 / (1 – 0.15)



= 23.24 / 0.85 = 27.34 mts.Work sampling study one day with 2 shifts of 420 min. each, produces 225 units. Allowance 12%

Work element 1 2 3 4

Frequency 50 90 75 85

PR% 90 150 100 115

Total duration mts 420*2=840

Observations 50 90 75 85 300

% working 50/300 90/300 75/300 85/300

16.67 30.00 25.00 28.33

Normal time 840* 0.9*0.1667

Normal time / unit 126/225

0.56 1.68 0.93 1.216

Std.Time in mts 0.56/(1-0.12)

0.64 1.90 1.06 1.38 4.98

• Time study is undertaken by selecting job. A job is selected for time study for the following reasons or when the following arise:

1. New tab is taken for production.2. Change in manufacturing method.3. Design change4. Change in raw material or material composition.5. Worker complains about inadequacy of time allowed.6. Bottle neck operations.7. High labour cost.8. For incentive scheme.9. When new tools, figs and pictures are used.Classification of elements in a job in Time Study



Every job consists of a series of elemental activity like movement of hands, reaching, grasping, loading etc. An element is a distinct part of the job which can be clearly specified and the activity has a starting and ending time which can conveniently be observed, measured and analysed.

The elements are classified according to the nature of that part of the job:-

1. Repetitive – Occurring in every cycle of operation.2. Occasional – occurring at intervals.3. Constant – basic time which is constant.4. Variable – basic time which varies.5. Manual – done by worker.6. Machine – automatic work.7. Gushing – occupies the longest time.Foreign – unnecessary element.


6 Ergonomics,Works Study - Method, Motion and Time Study POM Hand Out 6

Documents

Transcript of 6 Ergonomics,Works Study - Method, Motion and Time Study POM Hand Out 6