In-Process Quality Control for Manufacturing PDF

Preface

The idea that concerns about quality control are or should be an inherent part of all manufacturing operations is a readily understood concept. In addition, this philosophy is currently receiving a large amount of attention in the manufacturing community due to the increasing challenge to produce products that are competitive in price and utility in the world marketplace. In almost all instances, this means that today's manufacturing operations can be characterized by the fact that it is undesirable to make products that are not fit for their intended use (scrap). In order to accommodate this situation, a variety of solutions may be proposed to control the quality of the finished workpieces. Rigorous testing of each individual part can be employed at the end of the manufacturing cycle to establish the quality level of the process output (within the error limits of the inspection equipment). Then, through a selection process, it is possible to assure that the quality level of the products that the customer receives will meet the agreed upon requirements within a specific level of confidence. (For instance, it could be estimated ahead of time that 99.99% of all of the products that are shipped to a customer will meet specific performance requirements.) This may be an acceptable mode of operation as long as there is a sufficient market for the lower quality products and the customer with the higher quality requirements is willing to accept the extra product certification expenses that are encountered. However, this sorting procedure does nothing to control the actual quality of the manufacturing operation-it only establishes a historical data base that describes the results of the manufacturing process. An alternative approach for improving the quality of a process's output is to employ manufacturing techniques that depend on statistical quality control, as demonstrated by Demming and others.

Author: William Barkman