PROCESS CONTROL IN THE INVESTMENT FOUNDRY

摘要

There are many critical steps in the manufacture of investment castings. To obtain the high quality part required by the customer, a wide variety of input variables need to be controlled in each process step. Only by maintaining low variability of each step, can the variability of the final product be controlled. Poor quality and high costs result from the multiplying effect of this variability resulting in low yields in the final product. An effective quality system ensures control, stability and product quality as well as tracking of quality and performance. To be effective, a regular review of the quality and performance data is required. These results are used to determine the need to change control factors, to shift, expand or tighten control ranges, or to identify the need to perform corrective action. Setting up a formal quality control system initially involves formalizing manufacturing processes currently being used. This will involve identifying key factors that are not being controlled. Statistical process control steps are used to establish process and product quality control capabilities. Statistical process control techniques are then used to determine where and how control established processes can be refined and improved. This paper will discuss control requirements for each stage of the investment casting process. This will include raw materials, incoming products, operators and technicians, equipment, processes or process procedures and general plant and environment.