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BITSPilaniPilani Campus

Manufacturing Organization

and Management

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BITSPilaniPilani Campus

Fundamentals of ControlLecture 13

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BITS Pilani, Pilani Campus

Planned control of all activity is a basic characteristics ofmodern industry.

Effective control of people, materials, machines, andmoney contributes toward the making of profits so

essential to the free-enterprise system. Control of materials Their procurement and storage

The processing of these materials by workers and machines.

Introduction

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Manufacturing control:it is usually in terms of automaticcontrol of industrial manufacturing processes.

The principles of process control are well established andthere are many very successful applications ofautomatically controlled production processes in industry.

Basic principles that work well for controlling processescan be applied to the manufacturing managementprocess.

It will be instructive to look at some of the concepts ofprocess control before showing their use in management

control. Two types of control systems: Open loop

Closed loop

Control Fundamentals

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Open & closed loop heating systems

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The important distinction between the two systems isthat closed-loop systems have feedback, whereas open-loop systems do not.

Although open-loop heating systems of the type shownin figure no doubt exist, their operation consists of

manually turning the furnace on when ever heat isneeded, letting the unit run until the desired temperatureis reached, then turning the unit off manually.

No provision to control the temperature of the heatedspace automatically or to start and stop the heating unit

has been provided in the arrangement. No matter which phase of manufacturing requires

control, either singly or in combination, there must befour basic elements in the control system.

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These basic control elements are interdependent and

dynamic in all manufacturing situations. They are:

1. There must be a plan.

2. A record of actual performancemust be maintained.

3. Through feedback, actual performance must continually

be compared to and evaluated with the plan.

4. Provisions must be made for correct ive act ion in

manufacturing operations when the results of the

evaluation indicate the need for such action.

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A state of control can never exist unless some sort of aplan has been made.

In manufacturing organizations, the plan generallyconsists of three elements: pol ic ies and procedures,long-range plans, and short-range plans.

Company policies and procedures are organizationalguidelines used to describe how routing function of day-to-day operation are to be handled.

Procedures which can include items such as the warningof eye protection in designated areas, company travel

policy, and so on, are generally documented in standardpractice manuals.

Other documentation, such as Q/A manuals and operatingmanuals used within departments, are further evidence ofcontrol.

Plan

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It should be pointed out that long-range planning hasbecome increasingly difficult because of changingtechnology, greatly intensified world competition, thegrowth of government regulation and its effect onbusiness, and the continuing inflationary spiral.

Successful companies also understand that their growthand possibly their very existence do not dependexclusively on what they are doing today but rather whatthey planned to do years ago.

Plans can be identified with workers, materials,

machines, or money, or with any combination of theseelements of manufacturing.

However, in making a plan, a common yardstick formeasurement must be established.

Plan cont

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Any one of these elements may be used as a basis formeasurement, but the most common base formeasurement and as a result the foundation for mostplanning - is either money or time.

Time is the common denominator to which practically all

manufacturing elements can be resolved.

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All effort used in making plans is a total loss unlessattempts are made to follow these plans in themanufacturing activity.

Keeping records of actual performance on the samebasis of measurement as the plan is an activity that is

prerequisite to any system of control.

Actual Performance

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The comparison of the records of actual performance to the planand the evaluation of the results tell us how well the plan wasmade and how well it is being followed.

When the actual performance meets the planned performance,the manufacturing situation is said to be incontrol.

When performance fails to meet the plan, the situation isconsidered outof controlIt is possible to be incontroland stillnot be operating at optimum efficiency; such a situation shouldbe evident in the broad evaluation of performance.

Another aspect of evaluation is the prediction of possible failuresin the manufacturing activity by a study of trends in

performance. Anticipation of possible production bottlenecks or materials

shortages by careful study of performance is one of the mostvaluable tools to management.

Comparison and Evaluation

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Ideally, no corrective action should ever be necessary. Realistically, corrective action is the most important aspect in a

control situation.

Modern manufacturing is too complex to anticipate all possibilities ofdelays and failures when making the plan; and at the same time the

allowance of too much time or money in anticipation of suchproblems is not good planning.

As a result, corrective action is often necessary and should be takenwithout hesitation.

Corrective action does not recognize any change in the originalplan, for the objective of the corrective action is to get operations

back on the original schedule or budget. When such changes are made, the performance of the plant is the

controlling element not be plan. It is because of this that a state ofcontrol seldom exists except where effective corrective action isbeing taken.

Corrective Action

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Re-planning has its place in modern control situations. However, it is most effective when used to improve the

making of plans in the future.

The key to successful manufacturing controls is theconstant improvement of all plans for the manufacture

and distribution of goods. The use of a re-planto compensate for failure to meet

an original plan should be made only when one is awareof all the circumstance involved.

There may be external circumstances beyond the control

of the planner- for examples, a market demand changeor an economic downturn.

Re-planning

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For optimum results, there must be a clearly definedobjective for every manufacturing control situation.

This objective should state what is to be controlledand the degree of control that is to be maintained.

Control is a tool of management that requires carefulstudy and analysis in order to avoid theestablishment of controls for the sake of control only.

Degree of control means how close a control

needs to be maintained. The design and installation of control systems

present a challenging problem to the industrialengineer.

Common Characteristics of Good

Control Procedures

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Adequate and timely information:This is a principal characteristics of the second phase ina control system, the recording of actual performance.

Determination of the adequacy of information the system

will obtain requires considerable judgment. Enough information must be gathered for the making ofdecisions; however, in many cases the accumulation ofall the information that might seem desirable is tooshortly.

An economic balance must be struck between recordcosts and the value of the information obtained.Information must also be timely.

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Flexibility:Although it is generally agreed that re-planning should

be held to a minimum, a certain amount is almost always

necessary.

This requires changes in plans, with the resultantchanges in the control records.

In much the same manner, corrective action will require

adjustments in plans and schedules.

A good control system permits the making of such

changes without upsetting the apple cart and with a

minimum of confusion and expense.

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Permit Management by exception: The system of reporting actual performance and comparing andevaluating it with the control plan should be such that only situationsthat require corrective action are brought to the immediate attentionof management or supervisory personnel.

However, procedures should be so established that correctivedecisions can be made at the lowest level possible in themanagement structure.

Force planning and corrective action :

A control system can be so designed that management and thepersonnel operating the system are continually forced to look ahead.

Manufacturing control is dynamic in every aspect: it is not a static or

oneshotaffair. Good control plans should foster better planning for futureoperations.

Also good control plans force corrective action by signaling failuresto the next higher level of management

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People are involved in both management and labor.

They must be educated and trained for its effective

operation.

Recognition of need: A definite recognition of the need for the control must be established.

Losses due to ineffective controls can be identified and savings that will

result from better controls predicted.

The biggest obstacle is the natural human tendency to resist change.

It is often difficult to sell a new control plan to a management that is

currently making good profits with the present system.

The need for control must be clearly defined and constantly kept before all

people involved.

Manufacturing Controls andPeople

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Education and training:

A sound program and education and training will

materially influence the success of any control program.

More detailed education and training are indicated for

those personnel who will actually operate the system.

For optimum effectiveness, continuing program of

education and training is required.

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Recognition and reward: Important aspect of successful control is recognition and reward of

all effort of all people make control work.

Companies with proven long term records of successful operation

recognize and reward their employees not only for short term but for

long term performance as well.

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Many well-designed control system fail to produce the anticipatedresults.

It is not possible to enumerate all the factors contributing to suchfailures. However, we can consider briefly a few of the principalreasons why a control system of procedure does not functionproperly.

Any control system can be likened to a chain it is as strong oreffective as its weakest link.

Most control procedures are in reality a system of industrialcommunications consisting of many steps.

A failure at any point in the procedure contaminatesall subsequentresults that are recorded or observed by control personnel.

All information up to the point of failure is valid, after the point offailure all information is inaccurate and may contribute to inefficientoperation of the plant.

These are tow basic sources of trouble: operating personnel andbasic data.

Basic Causes of Control Failure

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It is obvious that incompetent personnel who continuallymake mistakes should be relieved of their assignments.This, however, may be only a short-range correction ofthe problem.

The failure of a clerk may be due to lack of proper

training. He or she did not understand the what,howand whyof the duties or their importance.

In the preceding paragraphs we discussed theimportance of education and training of personnel if thecontrol procedure is to be effective. Also, we pointed out

that personnel who are thoroughly competent must besoldon the system.

Sometimes a system fails because a single person doesnot do the job properly.

Operating Personnel

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The results obtained from any control procedure are nobetter than the accuracy of the information fed into thesystem.

Inaccurate costs, standard times, inventory counts, orany one of the other items of basic data upon which the

system operates will result in poor performance. One grossly inaccurate estimate as to either cost or

production time for a large component of a product mayresult in a poor plan for the control of production.

The reporting of an inaccurate count of materials in a

mass production plant may result in a completeshutdown of the lines.

Basic data must be as accurate as the degree of controldemands.

Basic Data

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Thank You

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