Dictionary · OEE component
Quality rate
Quality is the third OEE component: units right first time divided by total units produced. Scrap, rework and startup rejects live here. It is first-pass yield, not final yield — a unit that needed rework counts against you even if it eventually shipped.
Quality = Right-first-time units ÷ Total units
Nakajima's world-class floor is 99%. The rate looks like the easiest of the three to score well on, which is exactly why it hides money: at 97% quality on a high-volume line, the 3% is a full-time scrap-and-rework department nobody has hired on purpose.
Sources: Nakajima (1988) · ISO 22400-2:2014
Reading it on the floor
Common misreading
Counting reworked units as good. First-pass yield is the honest number: rework means you paid for the unit twice — once to make it wrong, once to fix it — and the second payment vanishes from a “final yield” figure.
First lever
Upstream control, not more inspection. Inspection finds defects after you've paid for them; parameter control (settings, materials, changeover verification) stops them being made. If quality dips after every changeover, the changeover procedure is the quality problem.
What good looks like
≥99% first-pass (Nakajima). Startup rejects after changeovers belong in this rate — excluding “warm-up scrap” is the most common way the number gets flattered.
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