Centralized versus decentralized inspection


Inspection may be carried out at the job place or in a separate inspection department. The location of inspection i.e. depends on various factors e.g. types of materials to be inspected, process flows, types of inspection and testing machines and equipments etc. When the testing and inspection machines are to be kept in special rooms with various facilities—air conditioning, maintenance of temperature at certain level etc. and they cannot be taken to- the job place materials, products, parts, components etc which are to be inspected, are taken from the normal flow to- the inspection department or to such a place where such machines and equipment have been kept or installed. Thus, when material, parts, products, components etc are sent to the inspection department for inspection it is called as central inspection. It is so because inspection is carried out at the one central place only. Central inspection saves the time of inspectors, because they have not to move out in various departments for their work, but they receive in the inspection department, what they have to inspect.

But central inspection cannot be used to inspect very heavy items and also huge quantity such as casting of 25 tones, an airplane, tones and tones of material etc. It cannot be used in case of such products also, which pass continuously and automatically from one process to another or from one operation to another operation and the maintenance of continuous flow is a must. In such circumstances, inspection is done at the job place.

Moreover, in case of central inspection, materials are inspected, only when inspectors are available and therefore many a times, persons from various sections have to wait for a long time, to get the material etc inspected. This lengthens the production cycle, because without inspection the material etc cannot be taken back for further operations. Material, products etc re required to be taken to and from central inspection department several times which increases the cost of handling and transportation. It also causes delay in production and it may happen that a large number of defective units may be turned out before the defect is discovered or final decision regarding acceptance or rejection is taken.

Inspection at the job place is used to resolve the problem. It is known as ‘floor’ or ‘patrolling’ or ‘first piece’ inspection. Here the inspectors move from one place to another place, to inspect the material during various stage of production and the finished goods. They get the machines set right before production starts and also they catch defective work before a large quantity has been produced. Products of semi-automatic machines are also checked from time to time and results are recorded. If operations are found out of control, inspectors can advise to- top the machines before heavy losses have occurred. Corrective action is immediately taken to set the machines right.

This type of inspection saves time, money and labor. Materials, parts, semi-finished and finished products etc are not required to be handled and transported very often to and from central inspection place. Persons from various sections have not to wait in inspection department for getting materials, parts, products, are inspected. Thus time of production cycle becomes short to so-me extent.

Continuous production becomes necessary when

1. The item is badly needed for own use or
2. The item is badly needed for timely delivery to customers or
3. The defects can be removed by rework with a small cost.

Now, the suppliers for materials, parts, equipment etc are selected with great care after considering their past history, their reliability, volume of business, goodwill in market etc. If after inspection and testing of number of lots received from them, it is found that the lots are satisfactory, inspection can be reduced for goods received from such suppliers. It will save the cost of inspection and also the transportation and handling cost for returning the defective goods etc. It is not advisable to do away with inspection and testing of materials etc received from such suppliers, but occasional inspection should be done.

Finally, for proper and reliable inspection and testing, the equipment and tools used for the same, should also be checked periodically and maintained properly. If this is not done, the results of inspection and testing may misguide the users and may prove useless. Now a days even the most reputed manufacturers call back their products from the market once some critical defect is experienced by a large number of customers after the sale, for free repair or replacement of a critical component. A practical example of this is Automobiles, Passenger Aircraft, Heavy earth moving equipments and even white goods.