New Job Start-up Procedures

Probably the most critical time in the life-cycle of a production component is when the part is first introduced to manufacture. Until that the time the volume produced has of necessity been kept to a relatively low volume. Components already in production have a proven track record and the need for high levels of test has been relaxed to a low level routine test by the production staff. The question as to how that final state is achieved needs to be answered by a clearly defined and documented route. For rubber injection moulding the route can be split into two rubber compound quality and component performance. 

The rubber has to satisfy a number of criteria. First it should meet the general standard of physical properties laid down by the customer. To demonstrate compliance the first five batches of compound are subjected to the full specification tests to which are added rheometer and thermogravimetric analysis (TGA). These last two provide a production marker that will show conformity for the cure rate and to composition. They are rapid tests and allow bought in compoimds to be used with a high level of confidence provided that the supplier of the compound has been audited and found to conform to the required standard. 

Components produced from the first five batches are subject to performance related tests to include load deflection, creep and fatigue. If a satisfactory result is obtained, production can proceed with tests on each batch of the rubber for rheometry and TGA. After 50 batches the standard deviation for all results is reviewed and the frequency of test for the compound can be reduced to a frequency set by the company and agreed with the customer. A similar test frequency can be set for the component. 

---