An interesting dilemma to ponder over…
I have recently been employed to look at a component facility and their approach towards risk assessments and validations. The volume going out every day is quite high and a batch size of 10 to 20,000 is very normal, with 2/3 batches a day coming off a machine. Inspection is done to an agreed AQL with the customer. However, due to the high risk nature of some of the components, a lot of customers are now 100% inspecting the components before use (this is a gap in itself, we cannot 100% inspect given the volume, it is not practical). This is resulting in customer complaints which on first glance seem to be quite high (depending on the customer and the their inspection criteria), however it may be one or more in 20,000. This according to our procedure means we have a low occurrence (1 in 25,000) however we are still getting a complaint in every batch sent out (which to me indicates there is a problem in the process), but the approach here is given the volume of product we produce, we have a low occurrence, and therefore does not need additional controls. However I am beginning to think that we need to look from a different angle and instead of units, maybe look at batches instead of individual units e.g. we had the same defect over 5 different batches, even if only 2 pouches affected from each batch this is a high occurrence. So instead of saying we had an occurrence rate of 10 in 100,000 units (very low occurrence rate), we had the defect in every batch (higher occurrence rate) and requires action. This discrepancy between our inspections and the customers is leading to a sharp increase in customer complaints, leading to irate customers, however given the volume of individual units manufactured, is it really a drop in the ocean??
Am I been overcautious? Would people accept the defective product given the volume that is flying out on a daily basis? Or do we need to increase our controls??? We are still (probably) within our 32 defects per million (CPK 1.33)