1) Tool dig mark because of wrong reference.|2) After entering the CRC the operator performed step run to verify the wall thickness but after verifying the operator pressed reset and entered the correction and started the cycle without instructing proper reference.|3) Operator block searched in the program to enter the CRC value, after entering the value he did not started the program from the beginning insterd he pressed the cycle start from the point he entered correction due to which the reference value was not properly calculated by the machine and caused to dig the part.