The Six Big Losses in TPM: What They Are and How to Attack Each
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The six big losses are the foundation of Total Productive Maintenance (TPM). Each is a distinct source of OEE loss with its own root causes and its own fix. Plants that try to attack them all with one tool fail. Plants that match each loss to its right countermeasure win.
This guide walks through the six big losses — breakdown, setup and adjustment, idling and minor stops, reduced speed, defects and rework, and startup losses — with a specific, tested tactic for each.
1. Breakdown Losses
Unplanned equipment failures that halt production for more than a few minutes. The most visible of the six big losses and the one plants attack first.
Best countermeasure: disciplined PM program plus root cause analysis on the top 3-5 recurring failure modes. Attacking breakdown losses without RCA just trades bigger failures for smaller ones.
2. Setup and Adjustment Losses
Time lost during changeovers, tool changes, die changes, recipe changes. Often the second-largest loss in batch or short-run production.
Best countermeasure: SMED (Single-Minute Exchange of Die) — separate internal tasks (done while equipment stopped) from external tasks (done while running), then systematically convert internal to external. Typical reduction: 50-75% changeover time.
3. Idling and Minor Stops
Brief stops under 5 minutes — misfeeds, blocked sensors, small jams, pause for inspection. Individually trivial, collectively enormous. Often unrecorded and therefore invisible.
Best countermeasure: Poka-yoke (mistake-proofing) at the stations that cause repeated minor stops. Add sensors to make invisible stops visible. One plant found 3.2% OEE leaking here once they started counting.
4. Reduced Speed Losses
Equipment running below its design speed — operators throttling for quality, wear causing vibration, product variation forcing slower cycles.
Best countermeasure: root cause why the speed was reduced, address the underlying issue, not the speed itself. If operators throttle to avoid defects, fix the defect source and the speed returns.
5. Defects and Rework
Quality losses after the equipment is running steady-state. The most expensive losses per unit because you pay for material, machine time, and labor twice.
Best countermeasure: statistical process control (SPC) with real-time alarms at key quality checkpoints. First-pass yield tracking by station reveals where the defects really originate.
6. Startup Losses
Defects and scrap produced in the period immediately after a changeover or shutdown. Often bundled with defects but deserves its own attention because the root cause is different.
Best countermeasure: standardized startup procedures, pre-run quality checks, and first-article inspection with clear pass/fail criteria before declaring the line "up."
Frequently Asked Questions
Why are they called the "six" big losses?
The framework originated with Seiichi Nakajima's TPM methodology in the 1970s at Nippon Denso, where he identified these six distinct production loss categories.
Which of the six big losses should I attack first?
The one with the largest contribution to your OEE gap. For most discrete manufacturing plants that's either breakdown or idling/minor stops.
How do I measure minor stops if they aren't being logged?
Install simple cycle-time sensors or IoT edge devices on the line. Any stop longer than the design cycle time is a minor stop. You'll typically discover 2-4% of OEE leakage here.
Do the six big losses apply to continuous process manufacturing?
Partially. Minor stops and setup losses are less relevant in continuous process; reduced speed and quality losses dominate. A modified framework (Asset Effectiveness or Total Effective Equipment Performance) is more applicable.
How long does addressing all six take?
A mature TPM program takes 2-3 years. But plants see 5-10 OEE points of improvement in the first year if they focus on the top 2-3 losses.
