As we know in foundry in contrast of other industries because of wide range of affective parameters on quality, it will be very hard and sometimes impossible to control all parameters and processes.
In these situation workers experiences and skills have an important role in quality. Technical knowledge and process control should decrease the fluctuations to produce sound casting in large quantities. But even with various tools of process control and simulation, defects could be appeared.
Nowadays in foundries 1 to 5 percent scrap rate is accepted as the nature of foundry. Therefore to do not deliver defective parts to customers foundryman should do something. We called it "Zero Escaped defects" . It means that we are responsible to be sure that only sound and defect free parts will be delivered to customers. Criteria for assessment of goal is returned parts rate. It should be near to zero.