On the basis of the study of quality control functions, we can say that to control the quality of a product, the quality is required to be controlled at various stages of production i.e. 1) at a design stage, 2) at a purchasing stage, 3) at a production stage and 4) after a product is sold (product support services).
Control at designs stage: Design and engineering department determines design / specifications / standard for raw materials, components, parts, tools, equipment, processes or methods of production etc. The information regarding quality and quantity of products required by the customers to satisfy their needs is provided by market research or sales department, which is being transformed into the product specifications. Product specifications or design should be based on the needs of the customer otherwise it will prove to be useless, even if it is outstanding. An error or a fault at this stage affects the quality of the final product adversely and the cost of production may also increase due to more scrap or spoilage or defective material.
Design standards, design drawings, design specifications, etc prepared by a committee of the head of various departments can serve the purpose in a better way. The quality control people have to see whether the predetermined standards, specification, drawings etc are being enforced properly or not.
Now the design standards, design specifications, design drawings etc determined once should be reviewed continuously, considering the changes in taste and needs of the customers and also technological developments. Sales people may provide information. Quality control people should see that design documents showing designs, drawings, specifications etc are up to date or not.
Control at purchasing stage: The responsibility for the procurement of materials, components, parts, tools, equipment etc of standard specifications, in a required quantity at a reasonable price rests with the purchase department. Efficient procurement gives better results. The quality of the final product depends on the efficiency shown in procurement. It does not mean that the materials, parts, components etc procured must be of the best quality because the best quality will cost more and a customer prefers that product, out of so many available, which he considers best for the money he is willing to spend. Thus cost is also to be considered, while procuring materials, parts, components, etc. Sometimes, the suppliers do not supply materials, parts, components, tools etc as per the specifications and delivery program, even though they are capable of doing so. Therefore, the suppliers should be selected after proper evaluation and after considering their reliability. Suppliers, who have supplied in the past materials, parts, components etc in required quantity as per the buyer’s specifications should be given first preference. Moreover, the quality control system or equipment of the suppliers should also be checked to determine their ability to supply quality materials regularly in required quantity.
All the materials, parts, components etc should be inspected at the receiving end to assure that the items procured conform to the predetermined standard as stated in the purchase order. Inspection at the supplier’s place only is not enough, because materials may get damaged during transportation and sometimes substandard materials, parts, components etc may form the part of total receipt. Substandard or defective lots must not be accepted, even if the suppliers have agreed to reduce the price to a great extent, because, it damages the goodwill of a manufacturer. The suppliers, who do not care for the quality and continue to supply materials, parts, etc of inferior quality, even after drawing their attention very often, must be deregistered from the reliable suppliers’ list. Purchase can assure the quality of purchased materials, parts, components etc, if it works carefully and with full responsibility.
New materials, parts, components etc are stored until they are used. Therefore, to preserve or maintain their quality, periodical checking should be carried out. If a separate stores department exists in a company, the responsibility of storage and issues of materials, parts, components, equipment, tools etc rests with it. If the method of storing is not proper the quality will deteriorate which in turn will affect the quality of a final product. Moreover, in the stores department, materials should be handled with care to minimize wastage.
Quality control people should see that strict control is exercised at the purchasing stage and storage facilities are proper.