The quality factor (also called quality rate, quality degree QG) is the ration of the yield to the produced goods and a measure for the loss due to defect parts which have to be reworked. The quality factor is used for calculating the Overall Equipment Effectiveness (OEE) and defined according to eq. 1 as follows:
Scrapping and reworking of defect parts are considered as quality losses. Momentarily present defect parts can easily be corrected by re-setting the machine. If such defects parts are repeatedly produced over a longer period, the indication of the error source identification tends to be more difficult.