Three kinds of control :
- control of the marking presence on the upper side of the nut. If the nut is badly oriented, it will be returned to the feed device.
- control of the absence of local marking where the hardness test has to take place. In fall of presence of marking in the field of the hardness test, the nut will be recycled.
- control of presence of thread on the nut. Absence of thread leads to ejection.