Wikia

Industrial Engineering

WorkStudy

Talk2
12pages on
this wiki
Work Study

Definition by ILO: Is a generic term for techniques, particularly method study and time study, which are used for the examination of human work in all its contexts, and which lead systematically to investigation of all the factors which affect the efficiency and economy of the situation being reviewed, in order to seek improvements.


Work study investigates the work done in an organization and aims at finding the best and the most efficient way of utilizing the available resources (man, material, money and machinery) to achieve best possible quality work in minimum possible time.

- which involves least possible time and causes least possible fatigue to the worker

Method study or Motion study Edit

Method Study is the systematic recording and critical examinaton of existing and proposed ways of doing work, as a means of developing and applying easier and more effective methods and reducing costs.

Work StudyAreas of Application

The application of methods engineering may be required in a variety of circumstances.
It ranges from the design of a new plant, to the design of a new product, to the design of
a new process, to the improvement of an existing process, to the improvement of an
existing workplace. Wherever work is being done, methods engineering is a desirable
function to ensure that the work is being done in the easiest, safest, and most
productive way.

Origin of Methods Engineering

Methods engineering grew out of the pioneering developments of the Gilbreths (Frank
B, and his wife, Lillian M.) who developed many of the tools of “motion study” as a part
of formulation a systematic approach to the analysis of work methods. Frank B Gilbreth
first become interested in methods analysis as an outgrowth of his observations of
brick-laying.

Gilbreth, who in 1885 was employed as an apprentice bricklayer, soon observed that a
journeyman bricklayer used one set of motions when laying bricks slowly, another set
when working at average speed, and still a different set when working at rapid speed.
As a result of his observations, he invented an adjustable scaffold and developed a set
of motions that greatly increased the number of bricks that could be laid in a day.

Organization for Methods Engineering

As indicated previously, methods engineering is a necessary function to ensure that the
most efficient methods are being used. This activity is most frequently performed by
industrial engineers; however, all engineers should be concerned with work methods.
The engineers may be assigned to a central methods engineering or industrial
engineering department or may be assigned on a decentralized basis to specific
operating departments.

Some multiplant companies maintain both a central industrial engineering group to work
on problems common to many plants and also assign engineers to each plant to work
on projects pertinent only to that plant.


Approach to Methods Design

Charles E. Geisel States that in order to design a system (method) thoroughly, eight
elements must be considered.

1. Purpose: The function, mission, aim or need for the system.
2. Input: The physical items, people, and/or information that enter the system
to be processed into the output.
3. Output: That which the system produces to accomplish its purpose, such
as finished steel, assembled toasters, boxes, and so forth.
4. Sequence: The steps required to convert, transform, or process the input
to the output.
5. Environment: The condition under which the system operates, including
physical, attitudinal, organizational, contractual, cultural, political, and legal
environment.
6. Human agents: The people who aid in the steps of the sequence without
becoming a part of the output.
7. Physical catalysts: The equipment and physical resources that aid in the
steps of the sequence without becoming part of the output.
8. Information aids: Knowledge and information resources that aid in the
steps of the sequence without becoming part of the output.

To ensure that the optimum method is found, a systematic approach to methods design,
superior to the use of a ‘hit or miss’ method, is used. Stated in simplest form, this
approach consists of the following steps:

1. Analyze the problem: Identify the problem and then secure all known
information about it through the use of appropriate analysis techniques.
2. Question are present method. If a method presently exists, question the
details of the known information to determine the principles violated.
3. Synthesize a proposed method: Formulate a proposed method for
performing the work, embodying all the principles of sound methods
engineering.
4. Apply the proposed method: Standardize and apply the new method.


Tools for Methods Analysis

Name of Chart Where Used
Flow Process Macro analysis; shows big picture of a production process
operation by operation; may be performed by visual
observation.
Operation – right and left- Micro analysis: Shows steps performed by a worker within
hand an operation; may be performed by visual observation.
Simo- simultaneous Fine micro analysis; uses threbligs for a very detailed
motion chart analysis of human motions; usually makes use of videotape
or motion pictures.
Multiple activity – worker Macro; may involve machines or several workers and time
and machine or crew is of significance, may be performed by visual observation
and/or videotape.


Process ChartHarminder Singh Hundal

A flow process chart is a graphic symbolic representation of the work performed or to be
performed on a product as it passes through some or all of the stages of a process.
Typically, the information included in the charts is quantity, distance moved, type of
work done by symbol with explanation, and equipment used. Work times may also be
included.

Right and Left – Hand Operation Chart
Symbol Name Activities Represented
Operation Modification of object at one workplace. Object may be
changed in any of its physical or chemical
characteristics, assembled or disassembled, or

arranged for another operation, transportation,
inspection, or storage.
Transportation Change in location of object from one place to another

Inspection Examination of object to check on quality or quantity
characteristics

Delay Retention of object in a location awaiting next activity.
Not authorization is required to perform the next
activity.

Storage Retention of object in location in which it is protected
against unauthorized removal.


Multiple Activity Chart


In those operations involving the combination of a person and a machine, a person and
several machines, or any combination of people and machines where delays are
prevalent, the multiple activity chart provides a convenient technique for analyzing the
combined activity. Very often the objectives of this type of analysis are to attain the
maximum utilization of a machine, to attain the optimum person to machine relationship,
or to bring about the best balance of crew activity.

For this reason, the time factor is an important consideration and necessitates the use
of a graphical representation involving time.

Use of Videotape

In the past, the experienced methods engineer found that one of the most important
aids was the use of motion pictures. There are many situations in which it is difficult to
observe all of the action taking place because of the high speed of activities or the
complexity of the operation.

Having observed slow-motion motion pictures, we are familiar with the fact that one can
take motion pictures at high speed and then, by projecting them at normal speed, slow
the action down. By the same token, we can take the pictures at slow speed and project
them at what appears to be high speed.

In using motion pictures, methods engineers may have had several objectives in mind.
First and foremost, they may have wanted a permanent record of the work as it was
being performed. Or they may have wished to use the film for analysis purposes,
commonly referred to as “micromotion” or “memomotion” studies, discussed in some
detail in sections that follow.

Micromotion Study

Micromotion study, which was originated by Frank B. Gilbreth, is one of the most
exacting forms of work analysis available for job improvement. It is an analysis
technique making use of motion pictures (or videotape) taken at a constant and known
speed. The film becomes a permanent record of both the method being used and the
time consumed in doing the work.

Although micromotion study formerly made use of motion pictures, very few companies
today are using them. As indicated earlier, videotape equipment has been developed so
extensively that it has virtually supplanted the use of the motion picture camera. Further
it is so cheap and easy to use that it makes the older approach archaic.

Micromotion study provides a valuable technique for making minute analyses of those
operations that are short in cycle, contain rapid movements, and involve high production
over a long period of time. Thus it is very useful in analyzing operations such as the
sewing of garments, assembly of small parts and similar activities.


Memomotion Study

Before leaving the general area of micromotion study, let us touch briefly on
memomotion study. Memomotion study, which was originated by M.E. Mundel, is a
special form of micromotion study in which the motion pictures or videotape are taken at
slow speeds. Sixty and one hundred frames per minutes are most common.

Memomotion study has been used to study the flow and handling of materials, crew
activities, multiperson and machine relationships, stockroom activities, department store
clerks, and a variety of other jobs. It is particularly valuable on long-cycle jobs or jobs
involving many interrelationships. In addition to having all of the advantages of
micromotion study, it can be used at relatively low film or tape cost (about 6% of the
cost at normal camera speeds) and permits rapid visual review of long sequence of
activities.

Principles of Motion Economy

Through the pioneer work of Gilbreth, Ralph M. Barnes and other investigators, certain
rules for motion economy and efficiency have been developed. Some of the more
important of these principles are the following:

1. The movements of the two hands should be balanced and the two hands
should begin and end their motions simultaneously.
2. The hands should be doing productive work and should not be idle at the
same time except during rest periods.
3. Motions of the hands should be made in opposite and symmetrical
direction and at the same time.
4. The work should be arranged to permit it to be performed with an easy
and natural rhythm.
5. Momentum and ballistic-type movements should be employed wherever
possible in order to reduce muscular effort.
6. There should be a definite location for all tools and materials, and they
should be located in front of and close to the worker.
7. Bins or other devices should be used to deliver the materials close to the
point of use.
8. The workplace should be designed to ensure adequate illumination,
proper workplace height, and provision for alternate standing and sitting
by the operator.
9. Wherever possible, jigs, fixtures, or other mechanical devices should be
used to relieve the hands of unnecessary work.
10. Tools should be prepositioned wherever possible in order to facilitate
grasping them.
11. Object should be handled, and information recorded. Only once.


Job Enlargement and Enrichment

This has led to the contention of a number of social scientists that hobs need to be
enlarged or enriched. Feedrick Herzberg, one proponent of job enrichment, feels that
the purpose of job enrichment should be to eliminate the undesirable characteristics of
highly repetitive, specialized work by enlarging it to include:

1. Greater variety of knowledge and skill
2. Giving a person a complete natural unit of work (module, division, area,
etc.)
3. More complex utilization of the important cognitive and motor abilities
possessed by the worker.
4. More freedom and responsibility in the performance of the tasks at hand.

Among the principles that commonly are applied in job enrichment programs, the
following are attended to by one large company.

1. Ensure that there is variety in the job content.
2. Include in the work situation an opportunity for the worker to grow and
learn.
3. Provide an opportunity for each worker to have knowledge of the part that
his or her job plays in the total manufacturing process required to produce
the product.
4. Design the work so that it has meaning to the worker and provides pride in
performance to the worker.
5. Ensure that the work is reasonably demanding and functionally inclusive.
Provide for self-direction of the work and for the checking of quality of
output.

Value Analysis

As a part of the approach to methods improvement, the methods engineer should
question the impact of the design of the parts, the materials used, and the equipment
used on the productivity of operations. That is, the methods engineer should be
thoroughly familiar with value analysis, an activity that is closely both to the methods
improvement programs and to purchasing and that is being used extensively in industry
and the government.

Value analysis is an objective study of every item of cost in every component part,
subassembly, or piece of equipment. This includes a study of the design, the material,
and the process in a continual search for other possible materials and new processes.
Value analysis involves the evaluation of an items function and relates its effect to the
end product. The purpose is to attempt to ensure that every element of cost contributes
proportionately to the function of the item.



Social and Economic Effects of method Study

As pointed out at the beginning of this chapter, modern industry is constantly searching
for better methods. When a business ceases to move forward, it will lost ground and
may eventually fail. It is for this reason that the major companies have organized
industrial engineering groups, work simplification and value analysis programs,
suggestion systems, quality circles, and other methods of achieving reduced costs of
manufacturing their products.

One of the consequences of these programs has been increased mechanization, which,
in turn, has led to the production of more and more goods per work hour. Among the
long-range benefits derived from this increased output have been higher real wages, an
improved standard of living, a shorter work week, and a reaction of the physical rigors of
the job.
--

Work Measurement or Time study Edit

Method Study – Systematic recording & critical examination of the way of doing a work as a mean for developing more effective methods & reducing costs.

Work Measurement – Establishing the time required by a qualified worker to carry out a specified job at a defined level of performance

Steps in Method Study - :

Select job or process to be studied
Record All the details concerning job
Examine Recorded facts Develop Most economical method
Define New method
Install New method
Maintain New method

Recording Techniques - :

  1. Process Charts
    1. Outline Process chart (or operation process chart)
    2. Flow Process chart (Man type; Material type; Equipment type)
    3. Multiple activity chart
    4. Two handed process chart (or Left hand-Right hand chart)
    5. SIMO chart (Simultaneous Motion Cycle chart)
  2. Diagrams
    1. Flow diagram
    2. String diagram
    3. Cyclegraph
    4. Chronocyclegraph
  3. Models

i) Outline Process Chart – Gives bird’s eye view of the process; considers only main operations and inspections

ii) Flow Process Chart – Detailed version of operation process chart shows the "OTIDS" Operation (transforms or performs work that the customer may see as Value which is the product or service Function at a Cost); Transport/Move; Inspection/Check; Delay/Wait and Store/File. Recent "OTIDS" have adde anoth D being Decision to become "OTIDDS". The use of "Value Stream Maps" in "Lean" (John Krafcik a research student at MIT in late 1980's) are enhanced for each major step in the Value Stream by using the Flow Process Chart to provide more details on the value and non-value activities in the Stream. Value Analysis/Value Engineering and Process Failure Mode and Effect Analysis techniuques in the Automotive qualkity and technical specificvation (ISO TS16949:2002) and Boeing Aircraft Corporation Quality Tools Manaul all use Flow Process Charts

Person type – Sequence of activities performed by worker

Material type – Sequence of activities performed on material

Equipment type – Sequence of activities performed by equipment


iii) Multiple Activity chart – Activities of more than one man or machine are recorded on a common time scale

iv) Two handed Process chart – Activities performed by two hands of worker are recorded on a common time scale

v) SIMO chart – Detailed version of two handed process chart (micromotion study)

vi) Flow diagram – Shows the relative position of machines and equipments and marks the path followed by man and material

vii) String diagram – similar to flow diagram except that path is traced by a continuous string or thread

viii) Cycle graph – To study the path of movement of operators hands;

A small electric bulb is attached to hand and photograph is taken by a still camera

ix) Chronocycle graph – Similar to cycle graph except that along with path it also shows direction and speed of movement. This is done by interrupting the light source so that path appears as a series of dots.


SIMO chart is Micromotion study whereas

cycle graph and chronocycle graph are Memo Motion Study

Memo Motion study involves time-lapse photography ie a still camera takes pictures of the activity at regular intervals (1 to 5 sec) unlike micromotion study which involves making a continuous motion film

Memo motion study is used for activities which are not required to be examined in fine detail but are still too fast to be recorded accurately by human eye.

Therbligs – are the fundamental hand motions which are performed over and again in any manual work, eg Search, find, select, hold, grasp, use, assemble, dissemble, inspect, release


-developed by Mr. Gilbreth (Therblig is his name spelled backward) -used in micromotion study

Work Measurement
Std. time for any job may be established by 3 methods:


Time Study (stop watch) Short cycle ; Repetitive jobs Work Sampling Long cycle ; Heterogeneous operations PMTS Short cycle ; Highly-repetitive jobs


Work sampling

Time

study

Synthetic time

P.M.T.S.

Analytical

estimating

Direct

Indirect

Work

Measurement




Work Sampling

In this a no. of observations are made over a period othat instant. The percent of observations recorded for a particular activity is a measure of the percentage of time during which that activity occurs.


Work Sampling is used for activities of very long duration which cannot be measured with stopwatch. Eg to find out actual working time of an operator in one shift.


It is based on Statistical theory of sampling – ie adequate random samples of observations spread over a period of time can construct an accurate picture of the actual situation of system.


No. of observations required for 95% confidence level and ±5% accuracy (ie we are sure that 95% of the time the average value will not be having error more than 5% of the true value.


N = 4p(100-p) (p = percent of occurance)

---------------                                                                                   (A = Accuracy required)
A2

StopWatch TimeStudy


Why do we break down the activity to be studied into elements?(why not measure time straightly)

To provide a detailed work specification

To separate value adding & non-value adding activities

To select best method by comparing work elements of different methods


Stopwatch – one revolution = 1 minute (1 deciminute = 1/100th of minute)


Normal time = Observed time * rating factor

Standard time = Normal time + allowances


Rating – Comparing the pace rate or performance of a worker against standard performance level

to take into account different operators’ performance level


Rating techniques-

Speed- Worker’s speed/speed expected


However assigning a rating factor and allowances are largely subjective in nature and depends on personal judgment of timestudy engineer


Allowances- it is the additional time provided over and above normal time to take into account time for relaxation, attending personal needs

  • Rest and personal allowances (to overcome fatigue incurred during working)
  • Interference allowances (to take into account m/c stoppages etc)
  • Special allowances (for activities which are generally not a part of work cycle)
In this we build up the total time for a job by summing up the times for different elements
Particularly useful for operations which are still in the planning phase and have not yet started (helpful in planning and scheduling)
  • Synthesis
  • PMTS (Predetermined Motion Time System)
  • Analytical estimating
Synthesis
Element time values are taken from a catalogue of elements time built from timestudies done in the past

PMTS also make use of previously collected data but it deals with basic human motions (or therbligs) of duration 0.1 seconds or less. Whereas in synthesis duration may be 3-4 seconds

Analytical estimating is used when past time data is not available and estimator has to rely on his past experience.


PMTS

  • For short cycle & highly repetitive jobs
  • Uses video film (micromotion study)
  • More accurate than stopwatch timestudies
  • No rating factor required but allowances need to be added
  • But can deal with only manual motions of the operation

Method Time Measurement

Work Factor Systems


1 TMU = 0.0006 minutes (TMU = Time Measurement Unit)

1 wink = 0.0005 minutes (used in SIMO chart/micromotion study)


Analytical Estimating


For long and non-repetitive operations ; Least accurate


(Machine elements – calculated from information of feed, speed, depth of cut etc)




Comparison

It is difficult to compare different work measurement techniques, as each technique has its own set of application


Work sampling is used for long cycles eg amount of time actually spent working by a worker in a shift


Time study is used for short repetitive cycles eg worker working on a assembly line


'''Bold textPMTS is used for very short cycles which require a very detail analysis (micromotion study)


Time

study

Work sampling

Synthetic time

P.M.T.S.

Analytical


Time Required

MAX

MIN

Accuracy

MAX

MIN


TIME & MOTION STUDY : A NEW PARADIGM


In theory there is no difference between theory and practice,
In practice there is …….


I realized it by myself when I undertook a project on time & motion study during my summer internship. On paper it looks very easy to do timestudy with a stopwatch. But when you actually do it you realize the practical difficulties associated with the traditional method.
stung

That’s why I picked up the cause in my final year project and developed a software which automates the process of time & motion study.


Details about it can be seen at the following URL -:


http://web.archive.org/20040901135623/in.geocities.com/time_motion_study

http://www.professays.com/faq/


Please go through it; its worth a watch……


Home About_IE IE_1 Quality WorkStudy New_Tech Manufacturing Contribute Contact

Around Wikia's network

Random Wiki