The Six Big Losses, With Examples You'll Recognize

The "six big losses" framework is nearly fifty years old, and it survives for one reason: walk any production floor with the list in your pocket and you can put a machine's name next to every entry within ten minutes. It's not theory. It's a field guide.

The six are really three pairs — two ways to lose Availability, two ways to lose Performance, two ways to lose Quality. Here's the tour.

1. Breakdowns (Availability)

The obvious one. The gearbox lets go, the seal fails, the sensor dies, and the line stands still while maintenance gets paged. Everyone already tracks breakdowns, roughly, because they're loud and they generate work orders.

What plants track less well is the boundary of a breakdown. The stop that gets logged is often "pump failure — 40 minutes." The actual sequence was: five minutes before anyone noticed, ten minutes finding the technician, fifteen minutes waiting on a part from the store room, ten minutes of repair. Only a quarter of the loss was repair. The rest was response — and response time is usually far cheaper to fix than failure rate. If your breakdown records don't separate "time to respond" from "time to repair," you're missing the easy half of the problem.

2. Setup and changeovers (Availability)

Every product switch, mold change, format change, and the adjustments that trail after it. On flexible lines this is routinely the single biggest Availability loss — bigger than breakdowns — and it's the one most often defined out of the numbers because it's "planned."

Include it. A changeover responds to improvement like nothing else on this list; plants routinely cut changeover time in half with organization alone, no capital. And watch the tail: the changeover isn't over when the machine restarts, it's over when the line is back at rated speed with good product. That last stretch of tweaking and nursing often doubles the real duration, and it hides between categories.

3. Micro-stops (Performance)

The bottle that tips at the infeed. The double sheet that trips the feeder. The photo-eye that needs a wave of the hand. Ten seconds here, forty seconds there, cleared by the operator without a second thought, dozens of times a shift.

No single micro-stop is worth writing down, which is why almost nobody writes them down — and why, added up, they're frequently the largest loss on high-speed lines. They deserve their own article, and they have one: micro-stops, the downtime nobody writes down.

4. Reduced speed (Performance)

The line is running, nothing is alarming, and it's making 160 a minute on a machine rated for 200. Sometimes there's a reason someone chose: a tricky material that jams at full speed, a worn feed screw, a downstream machine that can't keep up. More often the speed just eroded — turned down during some long-forgotten problem and never turned back up.

Reduced speed is invisible without a rated-speed comparison, because a running line looks like a healthy line. This is the loss that a good Performance number exists to expose. When you find it, ask when the speed was last changed and why. The answer is frequently "years ago" and "nobody remembers."

5. Startup rejects (Quality)

The scrap you make getting stable: the first minutes after a changeover, a break, a jam clearance, or a Monday-morning cold start. Fill volumes drifting into tolerance, temperatures settling, the first dozen parts short-shot or off-color.

Startup rejects hide because they're expected — "the line always does that coming up." Expected isn't the same as necessary. They cluster tightly around restarts, which means every Availability fix you make (fewer stops) quietly buys you a Quality improvement too (fewer restarts). Plants that count startup scrap separately from running scrap are consistently surprised by the ratio.

6. Production rejects (Quality)

Defects made during steady-state running — the leaking seal, the missing label, the part that fails the vision check at two in the afternoon with nothing apparently wrong. This is the classic quality domain, the one with the most existing attention: inspection, SPC, complaint investigations.

From an OEE standpoint the useful move is granularity. "Reject" as a single reason tells you nothing. "Underfill," "weak seal," "label skew" point at specific stations and specific causes. The downtime-reason tree matters just as much on the quality side.

Using the list

Don't try to fix six things. Take one line, put four weeks of honest data against these categories, and rank them. The distribution is never flat — two of the six will own most of the loss, and which two varies by line more than by industry. Changeover-heavy packaging lines bleed at #2 and #3. Older process equipment bleeds at #1 and #4.

The ranking is the strategy. The six big losses aren't a checklist to eliminate; they're a way to find out which two arguments are worth having first.