Chapter IV - Industrial Engineering -30.6.04

8/8/2019 Chapter IV - Industrial Engineering -30.6.04

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Chapter IV

Industrial Engineering:

The subject of industrial engineering primarily deals with effecting

appropriate improvement of methods of doing a given job and of adoptingscientific methodologies of measuring the time required to do a job. Afundamental job of industrial engineering is to scientifically study of givenwork, also called “work study.”

To increase productivity, two important functions of production managementare:

• Installation of the most effective method of performing the

operation, and

• The control of resources-mainly plant and labour required in carryingout the operation.

Work study, formerly known as time and Motion Study, fulfills these tworequirements through its two complimentary specialisations of Method

Study and Work Measurement.

Method study aims to determine the most effective method ofperforming a job, the most logical layout of manufacturing facilities, thesmooth flow of men and materials throughout the company to enableprocessing a job in the quickest possible time and at the least possible cost.

Work measurement, on the other hand, helps to determine the timerequired by the operator to complete specified task for the defined methodat the defined pace of performance.

Method study and work measurement though they are considered astwo separate techniques, yet they are closely related and complement eachother. The time for a job can be assessed accurately only afterstandardising the method, which implies that method study, should precedework measurement.



The relationship between method study and work measurement shownin Fig. 9 below.

Fig.9.: Relationship between Method Study and Work Measurement.

Method Study:

“Method study is the systematic recording and critical examination ofexisting and proposed ways of doing work, as a means of developing andapplying easier and more effective methods and reducing costs.”

Basic Procedure of Method Study: Method is an organised approach andits investigation rests on the following six basic steps outlined in the blockdiagram (Fig.10)

1) Select the work to be analysed.

WORK STUDY

Work MeasurementMethod Study

Work MeasurementCritical Analysis of

existing jobs to develop

easier & better method.

Define, install and

maintain improved

method.

To achieve improved

planning, improved

manning, basis for

financial incentiveschemes, labour cost

control, improved

methods, reliable indices

to measure an employee’s

progress etc.

To achieve improved

processes and procedures,

better working conditions,

better utilisation of

resources, improved

morale etc.

Resulting in higher

Productivity



2) Record all facts relating to the existing method.3) Examine the recorded facts critically but impartially.4) Develop the most economical method commensurate with plant

requirements.

5) Install the new method as standard practice.6) Maintain the new method.

Fig.10. Block Diagram of the steps in method study.

Let us elaborate each of these 6 steps or bit more extensively.

Step No 1:

Select the job

to be analysed

Record facts

relating to theexisting method

Examine facts

critically butimpartially.

Maintain the new

method.

Install the new

method.

Develop

Alternatives to theExisting Method

Purpose PersonSequencPlace Means

Economic Consideration

Technical Consideration

Human Consideration

Charting Symbol

Chartin Conventions



Selection of the Job: The selection of the job to be analysed is amanagement responsibility. The selection of the job should be done based onthe following considerations:

Economic consideration.

Technical consideration. Human consideration.

(a) Economic Consideration:

Economic consideration is the most important consideration in selectingthe most appropriate job, for conducting the method study. Under this jobmay be selected based on the following considerations:

i. Plant, department, section, or, machines employing excessive overtime.ii. Bottleneck operations, which are holding up other production

operations.iii. Operations involving repetitive work and liable to run for a long time.iv. Sections having an un-orderly movement of men and materials over

long distances.v. Operations requiring a lot of manpower.vi. Operations having poor utilisation of man and machine.vii. Operations producing high rejection./scrap.viii. Sections/departments from which too many suggestions for

improvement are received.

(b) Technical Consideration:

The considerations here are:

i. Operations producing excessive scrap, or, process defects.ii. Frequent complaints from workmen regarding jobs whose performance

standards cannot be achieved.iii. Operations involving frequent/close supervision, or, deployment of

skilled workmen.iv. Jobs having inconsistent quality.v. Operations inviting frequent requests from supervisors for relaxation

in allowed time.



vi. Jobs in which too many man-hours are spent in checking andrechecking work.

(c) Human Considerations

Human consideration is the greatest consideration of all. Method studymeans a change but a change, which is accepted; half-heartedly by theworkers and their representatives is really no good a change. A fewsituations when human consideration should be given preference over otherconsiderations are:

Workers complaining of necessary and tiring work.Poor morale evidenced by trivial complaints.

Repeated cases of accidents and health hazards.Inconsistent earnings when the earnings are tied to output.

Step No 2

Recording of Facts:

The next step is to record the facts about the existing method. But wedo not follow a descriptive methodology to record the existing method, and

use standard international charting symbols and conventions asrecommended by International Labour Institute, Genera (ILU). These are:

(a) Operation/ Activity represented by : ο

(b) Transport ..,,.. : ⇒

(c) Storage ..,,.. : ∇

(d) Inspection represented by :

(e) Delay ..,,.. : D

Using the above symbols we prepare the following types of charts.Besides we also represent the existing method through Diagrams. Thereare different types of charts and Diagrams as enumerated below:



Charts Symbol used Diagrams

(1) Operations Process Chart (OPC ) ο , (1) Flow

Diagram.(2) Flow Process: ο , , ⇒, ∇ , D (2) StringDiagram.

Chart (FPC)

There are 3 types of Flow Process Charts

(3) Multiple Activity: working

Chart (MAC), also called man- non-workingMachine chart.

(4) Two-Handed Process Chart (THPC): ο , , ⇒, ∇ , D

Let us take each one of them one by one.

1. Operation Process Chart.(OPC) :-

An operation process chart is a chart on which the major activitiesand entry points of materials are recorded to have a graphic view of theoperations and inspection involved in the process. Here we use only twosymbols Ο and .

Example 1: Auto-craft Pvt. Ltd. manufactures different precisionturned components and small auto-part assemblies in their factory. Outof many small auto-part assemblies produced in this company, there issmall assembly called relief valve assembly.

(Materials) (Man) (Equipment)



Operation Process Chart (OPC):Present Method.

Task : Manufacture of Relief value assembly.

Chart Begins : Raw materials/ Bought out parts in stores.Chart Ends : Completed Assemblies delivered to stores.Charted by : Abhijit NagDate of Charting : 7.4.04.

Obtain

Locks

Obtain

SpringsObtain (1/4)” Φ Bar stock for plumbers

Obtain 17A/F Enl.A.

Barstock for value body.Machine

blanks 1.00 2.50

Machine

blanks

Remove

Pip

0.05 0.05 Remove Pip

Heat Treat. --

0.15 C’less grind

OD.

C’less

Grind OD

0.10 0.70 Drill 2.5Φ cnrs.

hole

C’sink 2.5Φ

hite on both

sides.

0.16 C’less grind

threaded

length to pre-

rolling Φ

0.10 Roll threadsM10x4

0.60 Drill 2.4Φ

x

8mm deep.

7.50 Drill & ream

4Φ

x 25 mm.

0.10C’sink 2.4

Φ&

4Φ

.

0.05 Inspect.

2.50Assemblecomponents.

3.00 Inspect

Assemblies.

1

2

3

4

2

1

2

1

3

4

5

Ins ect 0.050.08

6

7

8

9

1

0

1

1

5

3



Summary:

Symbol Frequency Time (minutes)

15 15.69

3 3.10

Flow Process Chart (FPC):

Flow process chart is a chart, which sets out the sequence of flow ofwork of a product, or, any part of it through the section, or, thedepartment, or, the factory by recording the events under review usingappropriate symbols. In drawing the flow process chart, we use all the fivesymbols, namely, Ο , , →, D, & ∇ .

Flow process charts are of three types, the material type which showsthe events that occur to the materials till all the operations are completedon it; the man type which deplict the activities performed by the man, andthe equipment type which exhibits the activities performed by theequipment. Flow process chart (materials) is also called product processchart while flow process chart (man) is also called man process chart.

Why Is Flow Process Chart Prepared:

It is prepared to explore the possibilities of reducing distance travelled byman/materials.(to reduced the cost adding time and increase only the value adding times).

Avoiding waiting time and thereby reduce production losses. Eliminating operations, or, combining one operations with another. Evolving better sequence of activities.

Example 1: One of the industrial jobs involved the following activities:

i. Component was brought from stores 10 metres away from themachine.



ii. It waited near the machine for the operator to be free from hisprevious job (40 minutes).

iii. It was loaded on the machine (2 minutes).

iv. It was machined on one surface (4 minutes).

v. It was unloaded from the machine (1 minute).

vi. Activities (iii), (iv) and (v) were repeated till the component wasmachined on all the four surfaces.

vii. The component was then taken to the inspection bench, 20 metres

away from the machine.

viii. The component’s accuracy was checked (3 minutes).

ix. It was then moved to the work distribution centre, 10 metres awayfrom the inspection bench.

x. It was finally placed in the appropriate rack (0.50 mins).

You are required to prepare the flow process chart (materials) to recordthe above activities.

Answer:



Flow Process Chart ( Materials )

[Present Method]

Task : Machining of a component

Chart Begins: Component lying in the rack of work distribution centrebefore machining.Chart Ends: Component lying in the rack of work distribution centre aftermachining.Charted by: Abhijit Nag.Date of Charting: 08.04.04.

Summary:

Symbol Frequency Time (minutes) Distance (metres)

1

13

3

2

1

2L in in the rock

Re lace in the rack

Inspected for accuracy

To Ins ection bench

Unloaded from the

machine

Machined on one side

Loaded on the machine

Waited for the operator

to be free

Component lying in the

racks of work distribution

centre.

Repeat for 4

sides

10 metres 1

40

2

4

2

3

3

0.5

20 metres

To work distribution centre10 metres



13 28.50 --

1 3 --

3 -- 40

1 40 --

2 -- --

Other Numerical for Students to Solve and Practice:

Numerical No. 1:

The following represent the procedure to testing concrete pipes. Form the

storage yard the pipes are loaded on the four-wheel trolley and transportedto the inspection shed 50 metres away. After unloading, the pipes wait from60 minutes till inspector marks the identification number on them. Themarking takes 10 minutes for a trolley load of pipes (50 nos.). Tests forleakage and straightness are carried out on each of the pipes in sequence,the tests taking 10 minutes and 4 minutes respectively. The acceptance /rejection tally is marked on the pipes. This takes 5 minutes. The pipes arethen loaded on the four-wheel trolley and transported back to the yard (50metres). At the yard, the accepted and rejected pipes are separated (5

minutes) as per the marking and stored in two groups for furtheruse/disposal.

You are required to prepare the flow process chart (materials) forthe above activities.

Numerical No. 2:

The following represents the procedure of manufacturing aluminium discs

for single-phase energy meters. The aluminium discs used in energy metersare made from 1 mm. thick aluminium sheets (8’ x 3’). These sheets arestored 10 ft. away from the shearing machine, where they are first cut intostrips of 91 mm width, giving 10 strips for each sheet. The strips aretransported over 4 feet and kept in racks to wait for further operations.From these racks they are taken to a 10-ton power press located 10 ft. awayfrom the racks. Here the strips are blanked into discs. In the same



operation, the edges of the discs are serrated and a centre hole is punched.The blanked discs are taken to a degreasing tank located 60 feet from10-ton press. The degreasing is done in trichlorocthylene vapours. They arethen taken over 60 feet to a 100-ton power press where the discs are

embossed to give rigidity. They are again taken for degreasing. They arethen transported over 50 feet to the inspection centre and after inspection,they are taken over 120 ft. to the stores.

You are required to prepare a flow process chart (materials) forabove process.

3.Multiple Activity Chart, or, Man-Machine Chart:

A multiple activity chart is a chart on which the activities of morethan one subject are recorded to indicate their interrelationship in a givenwork cycle. In other words, this chart shows what each subject does at anytime in relations to the other.

Why is it Made?

A multiple activity chart is prepared to:

• Detect idle time on man and machine.• Established the number of machines that can be handled by the

operator.• Determine number of operators required to perform a job involving

team working.

Chapter IV - Industrial Engineering -30.6.04

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