What Is Quality Rate in OEE? EDGEBIC Definition

Quality rate is the OEE factor for defect loss: the share of pieces that came out acceptable the first time. In EDGEBIC by User Solutions, it is good pieces divided by the total of good, scrap, and rework pieces. A run that produced 105 good, 3 scrap, and 2 rework has a quality rate of about 95.5 percent. It captures every piece the machine made that could not be shipped as-is, whether the bad pieces were scrapped or reworked, and it is the third factor that multiplies into the overall equipment effectiveness score.

This entry is part of the EDGEBIC glossary series. For the broader planning vocabulary, see the manufacturing glossary. Quality rate is the last of the three factors behind overall equipment effectiveness; the others are availability and performance rate.

How Quality Rate Works

Availability handles lost time, performance rate handles lost speed, and quality rate handles lost pieces. It asks the simplest question of the three: of everything the machine made, how much was right the first time?

EDGEBIC computes it from three piece counts logged as production punches:

• quality rate = good pieces divided by (good + scrap + rework), capped at 100 percent

Both scrap and rework count against it. A scrapped piece is an obvious loss, and a reworked piece counts too, because the factor measures first-pass acceptable output, and a piece that needed fixing did not come out right the first time. The distinction between scrapping and reworking matters for cost, but not for this ratio.

The important behavior is what happens when there is no punch data. EDGEBIC does not assume perfect quality. If a work center has no production punch rows in the window, quality rate shows n/a rather than a fabricated 100 percent, and because OEE is the product of all three factors, the OEE column shows n/a as well. The report would rather show an honest blank than inflate the score with a quality figure nobody measured. That is why capturing punch counts is the price of a real OEE number.

A Concrete Example

Take CNC-1 over a 5-day window. Production punches for the window record:

• Good pieces: 105
• Scrap pieces: 3
• Rework pieces: 2

The quality rate:

• quality rate = 105 divided by (105 + 3 + 2) = 105 divided by 110 = 95.5 percent

Combined with 80 percent availability and 85.9 percent performance, the composite is:

• OEE = 80 times 85.9 times 95.5 divided by 10,000 = about 65.5 percent

The reading: quality is the strongest of CNC-1's three factors at 95.5 percent, so only about 5 percent of output needed scrapping or rework. The bigger drag on OEE is the availability loss, the lost day. Quality rate does its job by ruling defects out as the main problem, pointing the supervisor at time rather than quality for this machine.

How EDGEBIC Uses Quality Rate

Quality rate is a column in EDGEBIC's OEE report, beside availability, performance, and the composite OEE, along with the raw good, scrap, and rework piece counts it is built from. It is computed per work center for the range you select, from the production punches captured during actuals logging. The report's structure and the way the three factors multiply are covered in how to run the OEE report in EDGEBIC.

Rows are sorted with real OEE values first and n/a rows at the bottom, so a supervisor sees the machines with complete data before the ones still missing punch counts. If half your plant reads n/a on quality and OEE, that is the report telling you where defect capture has not started yet, not that those machines are perfect. Getting punch counts logged is what turns quality rate, and with it the full OEE score, from a blank into a number you can act on.