DEVELOPMENTS IN QUALITY IN PLASTICS MANUFACTURE.

Feedback to functions such as Design and Production Control is important to ensure improved manufacturing reliability. With the advent of automated handling and the incorporation of in-line measurement a way has been opened for the exploitation of direct statistical machine control. Advantages include the ability to anticipate out-of-control situations and to apply corrective action before defective products are produced. In tracing the development of machine control towards this goal several stages can be identified. Discrete controllers were originally used to control processing variables within certain limits; this was followed by the use of tooling control systems involving measurements of variables such as pressures and temperatures of material; practical control systems based on direct component measurement require some form of automated handling of the product. A variety of machines is now available which incorporate the capability of handling and some form of measurement for each component. 6 Refs.