Quality management is a company wide activity and various functional departments contribute to its success. The marketing department, specifically market research has information about: what quality characteristics the customers desired and to what extent? This is a valuable input for planning quality. Also the information regarding the quality of the manufactured products needs to be presented to the customers. This is also done by the marketing department. Product design writes the specification for the product, raw materials, bought-out parts, and the contracts with the customers. The purchasing department makes contracts with the supplier of raw materials and selects the vendors. Naturally, product design and purchasing have much to contribute to the quality of the final product. Production engineers select the processes, methods, and equipment for the manufacture of the product and can provide valuable information regarding the anticipated difficulties in implementing a certain product quality specification. The contribution of manufacturing line is obvious. They are responsible for the actual production, and therefore the final product quality depends much upon their skills, motivation to work, and their interpretation of the specifications. Since the finished product may take as much as one year before it reaches the final consumer, the product quality depends upon the design of the packaging and the method for storage in the warehouses. The quality depends also on how the product is shipped. The purpose of good product quality is to create a good feeling for the company in the minds of the customer and this feeling should be sustained. Therefore the company has to attend to the complaints from customers and provide periodic services to the customers. The quality control laboratory inspects a batch of raw materials, or semi-finished goods or finished goods or finished products and approves or rejects them as much to contribute to quality. Many a time, the quality control job is misunderstood because of this last function alone. The product quality has inputs from various angles and a total quality control program should consider all the different aspects contributing to quality. It is stated by many that â€œquality is everybodyâ€™s job in a businessâ€. When we take a look at the organizations whose products are of top quality, we always notice that in such organizations all the company employees at all levels and in all functions are motivated to contribute to the total quality establishment effort.
Customer service is at the heart of quality:
Of late, the perception as to what constitutes Quality has undergone a metamorphosis. Quality is regarding the performance of the product as per the commitment (written or unwritten) made by the producer to the consumer. It does indeed concern itself regarding the control of defectives in a manufacturing environment and or complaints in a service environment. However, the scope of quality as a concept has expanded beyond its conventional definition. Defining quality as only lack of non-conforming product /service would be taking a very limited view. The prevailing new paradigm for world class quality is Total Customer Satisfaction. The customersâ€™ expectations are therefore, paramount. Customer service is at the heart of quality for physical products as well as services .
Genichi Taguchi, a Japanese engineer, realized the importance of cost associated with poor quality and its impact on corporate profitability. Taguchi did not confine himself to the corporate losses alone but took consideration the losses due to poor quality to the society. His principle states that for each deviation there is an incremental economic loss of geometric proportion. The cumulative effect of the functional variations of various products can be very great, although these products may just deviate only a little from the target value of a measurable quality characteristic. Our traditional view has been that there is no negative effect as long as the products / components are within their respective engineering specifications. The whole Statistical Quality Control, with its percentage tolerances and the Upper and Lower Control Limits, is based on this traditional view. In our Statistical Process Control so far, we have seen 3-sigma control limits and â€˜percentâ€™ defectives As long as the process is within these limits, the process was considered to be â€˜in controlâ€™ or â€˜normalâ€™ and it was not to be disturbed. Taguchi, however, (contrary to this view) says that the point to consider is the cumulative impact of the deviations from the target value. Tagiuchi developed a mathematical model in which loss is a quadratic function of the deviation of the quality of interest from its target value.
Taguchi methods of quality control, therefore, involve the online and offline methods. On line methods include the use of statistical process control charts amongst others so that the aspect of reducing deviation about the target value care of as far as process or manufacturing is concerned. The off line methods involve market research, product design and development, and process development.
The tolerances, the key process variables and the overall system need to be so designed that the variations in the end product are minimized. The variations from the target values are very important and these variations are to be reduced as much as possible. While it is necessary to be â€˜accurateâ€™ it may be better to be â€˜precise while being inaccurateâ€™ than to be â€˜accurate but impreciseâ€™. For example, between the two hits on the dartboard, the former should be preferred; because, although the darts have missed the bullâ€™s eye, with a correction in the direction of hit, most of data will hit the bullâ€™s eye. This cannot be said of the more variable process.
The definition of quality is changed from â€˜achieving conformance to specificationsâ€™ to â€˜minimizing the variability while achieving the targetâ€™. An important aspect of philosophy is its linking of the quality of a manufactured product (total loss generated by the product) to the society. If these variations are to be minimized then one has to resort to the Design of Experiments (DOE) in order to identify the factors which are responsible for the variation, to find the relative impact of the factors on the variability and hence to suitably select a combination of input parameters to achieve the result.