1. 100% Inspection
This is inspection of every item supplied by the supplier. This method of inspection is appropriate for high value items which cannot be destroyed during inspection. It is also appropriate when the material have a significant effect on the quality of the final product.
2. Sampling Inspection
Sampling is a set of procedure or a method of selecting some part of a group to represent the whole or total. The advantages of sampling over 100% inspection have been recognized relatively arbitrary and crude spot checking procedures being employed long before the development of statistically based sampling techniques. To be successful an acceptance sampling plan must be designed to suit each particular case seeking an economic balance between the cost of inspection and the increased cost of processing defective items. If the defective parts are dispatched to customers a balance between the cost of re-handling, replacement and possible loss
of goodwill verses the cost of increasing the cost of quality control and inspection effort. In the simplest form acceptance sampling decision are based on the testing of a sample size (n) taken at random from the batch size or population size v(N). If a rejection condition is indicated it is usual to carry 100% inspection of batch. In general acceptance sampling is appropriate where:-
- Inspection involves destructive testing
- The costs of acceptance of defective items are not prohibitive.
- Materials arrives in large batches
- It is possible to take truly random sample
- It is economically feasible to consistently identify material as acceptable or not.
- 3. Inspection by storekeeper
Where there is no separate inspection department or where that department deals only with a limited number of commodities the storekeeper may be required to undertake the examination of goods for quality as well as quantity. He is therefore provided not only with a copy of official order by the supplier but also with relevant specifications or samples and with suitable equipment necessary for the degree of inspection which he is required to perform. In those circumstances the storekeeper signs the goods received note not only for receipt of the goods but also for their inspection.
4. Inspection by Technical staff
In some organizations, inspection arrangements by storekeepers may also be supplemented for items of a technical nature by some degree of examination carried out by suitable members of the technical staff such as the plant engineers or works manager. Appropriate instructions should be issued making clear to all concerned which items are to be inspected by storekeepers and which require also the signature of a technical officer.
5. Inspection by inspection department
Inspectors have authority to accept or reject materials and endorse goods received note accordingly, unless separate inspection certificates are prepared. Storekeepers are instructed that goods awaiting inspection are to be segregated in separate place in the storehouse and that they are not to be made available for issue until cleared by the inspection department.
6. Inspection at supplier’s premises
In large organizations particularly government departments arrangements may be made for materials to be inspected at the suppliers premises including in some cases examination during the various stages of manufacture. Where this is done, an inspection certificate is given before the goods are dispatched and no inspection or at least only a limited check is necessary at the point of receipt. In these circumstances a copy of the inspection certificate is sent to the storekeeper as soon as it is available. This avoids the need for the material to be held in the inspection bay and it can be put away in its appropriate place in the storehouse immediately on receipt, thus avoiding double handling.
7. Spot checks
Spot checking is the practice of making random checks of some stores items at irregular and unspecified intervals. It is often done by senior stores officials in the course of their supervisory duties, but can be operated in parallel with the stocktaking program, irrespective of whether the periodic or continuous method is used.