Control of quality


Today, in the modern era of industrialization products are being produced on a large scale to take advantage of mass scale production. Things like tooth brushes, tooth-pastes, screws, nuts, bolts, cloth, sugar etc are produced in huge quantities everyday. But one screw is not exactly the same as another in all respects. There are bound to be some variations in the size or composition of a product. For example, if screws of length 1.5cm, are produced, some screws will be slightly longer than 1.5cm, say 1.59cm or 1.6cm etc and some screws will be slightly smaller than 1.5cm say 1.49cm or 1.4cm etc. Variations within certain limits are tolerable, as they are unavoidable, but if they are too large, the product becomes useless. Maintaining the quality of a product means keeping the size and composition within the tolerance limit. Quality control is the actual checking or completion of various tasks involved in the quality procedures which have determined within the quality assurance function.

Cause of Variation:

The factors which cause variations in the size or composition of a product can be classified into two classes:

1. Chance variation, and
2. Assignable cause of variation

Chance variation arises due to a large number of factors which are out of everybody’s control. These chance causes of variations can neither be discerned nor removed. Chance causes arise from so many very sources that even if a few were found and something one about them, the overall effect would be negligible. These types of variations may take place due to a slight variation in the electric current supplied to the machine, or a slight variation in the machine.

Assignable causes of variations are disturbances that can enter the system undetected until large penalties are paid for poor quality of production that has occurred. There may be variations due to negligence of the operator or due to the disturbance in the process or some faults of a machine. Variations caused by these factors are generally high. When such cases are present quality of a product is lost and we say that the process is out of control.

Functions of Quality Control:

The functions of quality control include the following:

1. To see that the product is designed in such a way to meets customers’ demand. It is the function of design and engineering division.

2. To see that the product is not harmful and that the instruction or warning is given on the product in the form of leaflet. If there is no proper instruction or leaflet than or if the product is harmful than the firm or the manufacturer has to face a legal action or litigation.
3. To maintain interest for the workers to work there should be an healthy atmosphere. The quality of products in a particular unit depends upon the performance of the workers working i.e. more the sincere effort will increase the level of quality of the products.

4. To see that the materials, parts, components, tools, equipment etc of standard quality only are purchased and used. Use of sub-standard material results in more scrap or defective materials. The defective material increases the cost of production. If a material worth Rs. 50 is inspected before it is sent for further processing, it saves Rs. 500 at the final stage, because the cost of labor and overheads spent on the same during the production cycle is saved, if it is found at the initial stage that the material is defective.

5. To provide current information on variations and trends sown by the process for the purpose of control: It is necessary to find out the causes of variations so that corrective can be designed in a proper way.

6. To make the employees quality conscious by fixing their responsibility at various stages of production: A particular employee can be held responsible for a certain defect, if the stage of defect is identified. A worker may have worked with full responsibility but there may be a fault in a machine also. Therefore the responsibility of a defect found out afterwards must determined very carefully.

7. To reduce the wastage or scrap during the process: The causes should be studied carefully and the points or stages of such losses should be identified, so that corrective action is taken to reduce the wastage and scrap.

8. To see that product support services are provided satisfactorily after the products have been sold. This factor also affects the goodwill of any manufacturing unit and therefore it is very important to maintain service stations region wise in the market area with proper staff and equipment.

The word ‘Quality control’ is changed to ‘Quality Assurance’ because the word control was giving a dual meaning like ‘inhibiting quality’. The latest is ‘Total Quality Management’ or TQM which means the Quality assurance is just not restricted to manufactured goods but the entire spectrum of all Organizational functions.