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This is probably the most important of all the principles. Unless the information is timely. it is useless. This of course. also applies to adequate and accurate information. All information that is obtained in the system must have these three qualities to avoid production delays. As previously "pointed out, communication information flow is the basis of any production control system. 2. Be Flexible.

When reference is made to the flexibility of a system, it refers not only to the systems ability to adjust for variations in work loads. but also flexibility in terms of modifying the system itself to accommodate changes in the operation of the conditions that exist in the activity. Activities are dynamic; i.e. they are III a constant state of flux. This is particularly true under conditions of rapid growth. Just because a system that has been designed is adequate for conditions as they exist today does not necessarily mean that it will be adequate for conditions that will exist in the near future. Because of this it is necessary for the designer to keep in mind at all times that a system must be adjusted to changing conditions within the organisation. This may be done without completed disruption of the work that has been done in the past 3. Be simple and understandable.

By simplicity we mean that the system must be understandable to everyone connected with it. This does not mean that the system in all phases must be understandable to everyone. It only means that the part of the system which applies to an individual in a particular function must be understandable to that individual. . 4. Be economical.

Economy of course, is the basic reason for having a production control system. In all cases. we must get back more than a rupee for every rupee that is spent in planning and control. This is also one of the most difficult steps to evaluate.

Many of the benefits accrued by production control are intangible, and cannot be given in dinars. Only by comparing the cost of operation when no formal system of production control was used against the cost when a production control system is used could the economy be measured accurately.

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28.12. TYPES OF PRODUCTION (MANUFACTURING) SYSTEM Modes. of manufacture. which may affect production planning and control system, include three main relevant factors:

(1) The type of production i.e. the quantities of finished products and regularity of manufacture.

(2) Size of the plant.

(3) The type of industry i.e. the field of specialisation of the plant.

The types of production systems can be broadly grouped into three headings according to the volume of production and the regularity of manufacture:

(A) Job production. (B) Batch production. (C) Continuous production.

(A) Job Order Production.

Job order production is the manufacture of products to meet specific customer requirements of special orders. The quantity involved is small. usually one off or several off. This type of production is mainly concerned with special projects. models. proto-types, special machinery or eqUipment to perform specialised and specific tasks. components. or subassemblies to provide replacement or repairs in existing machinery etc. Examples. turbo-generators. large engines. material handling systems. shipbuilding and many other manufacturing activities are of the job production group.

Three types of job production can be defined. according to the regularity of manufacture:

(a) A small number of pieces produced only once.

(b) A small number of pieces produced intermittently when the need arises. (c) A small number of pieces produced periodically at known intervals of time.

When the order is to be executed only once, there is little scope of improvement of production techniques by employing costly method studies, research, special tools, or jigs and fixture, unless the technical requirement Justify It.

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But, II the order is repeated. tooling and jigs as well as specially designed inspection gauges should be carefully considered because the effect on production time may be considerable:

In this type of production, the products are made when orders are received from customers. One order may be all together different from the other. Therefore. prior planning becomes complex. Skilled labour is necessary to handle variety of jobs. General purpose equipment is used since it can handle variety of jobs.

The output of the shop in job production is mainly governed by plant capacity and as soon as the load presented by incoming customer orders exceeds this out put a queue of orders is formed. When immediate increase in plant capacity is impractiable the length of the queue is a major factor governing the sales policy of such plant, and a certain amount of discrimination in order selection may be essential. .

Scheduling is dependent on assessment of production times, and estimating (although it can be greatly improved by experience and skill of estimators) is based on judgement and is too often reduced to a rule-of-thumb affair. Scheduling must therefore be constantly amended to take account of reality. Repeated orders for the same items usually do not require repeated planning. Production control is also simplified in the case of repeated orders, especially at regular intervals. The master schedule can also be constructed in which production time is balanced against plant capacity, but such a state of affairs is rather rare. Usually the majority of orders are executed only once. and a small percentage of them may be repeated regularly or intermittently.

Characteristics of Job Order Production: