Measuring the effectiveness of a maintenance program is about quantifying important variables such as machine efficiency and reliability. Deducing these variables means diving even deeper and measuring the systematic performance of a machine. For this, manufacturers must investigate the “six big losses.”
A quick look at TPM
The six big losses are unique issues within a total productive maintenance (TPM) program. The goal of a TPM program is to reduce and eliminate breakdowns, defects, and inefficiencies — qualified by the six big losses. More than just qualifying these losses, a good TPM approach provides ways to remedy issues across different maintenance facets, including:
- Breakdown maintenance — which involves repairing equipment as it breaks down.
- Preventive maintenance — which involves repairing equipment to prevent breakdowns.
- Corrective maintenance — which improves the reliability of maintenance results.
- Maintenance prevention — which improves equipment, thereby reducing maintenance.
TPM is a course of lean manufacturing, which means it focuses on pinpointing and eliminating waste. The six big losses are so named because they represent the entire scope of waste within a maintenance approach and help qualify the approach required to address TPM.
Identifying the 6 big losses
The six big losses are distinct problems with distinct outcomes — all of them attributing to waste. They’re characterized by the type of loss they generate, as well as how they impact overall equipment effectiveness (OEE): specifically affecting availability, performance, and quality. Here are the six big losses:
1. Unplanned stops — This includes any unplanned breakdown. It’s caused by anything from equipment overheating, to component failure, to tooling failures, and more. Unplanned stops directly impact machine availability, hampering total production.
2. Setups and calibration — These issues occur during planned changeovers or adjustments and are the result of maintenance inaccuracies. Again, machine availability suffers, because equipment isn’t operating at its fullest capacity.
3. Small stops — This category includes jams, misfeeds, blockages, venting issues, and anything else that impacts productivity. Small stops are a performance issue and can be among the easiest waste issues to fix.
4. Slow running — Equipment wear and alignment problems are two examples of slow running issues. This is another form of performance loss and can bleed over into other issues, such as production defects or reduced yield.
5. Production defects — Any time a finished product falls short of expectations, it’s a defect. Defects are often scrapped, representing twofold waste: the scrap and the time used to make it. This is the most significant form of quality loss.
6. Reduced yield — Another form of quality loss, machine inefficiency leading to stunted production represents the reduced yield category of waste. Machines require maintenance to resume operation at full capacity.
While the six big losses can overlap and act as catalysts for one another, each requires distinct attention to remediate. Within a TPM program, maintenance techs should have different approaches and resources to address each form of loss.
The goal of any TPM program is to improve OEE, which first means addressing the six big losses. Targeting availability, performance, and quality issues has a direct impact on OEE, raising the availability, reliability, and efficiency of equipment.
Within your TPM program, isolate issues and categorize them within the six big losses. From there, choose the maintenance approach that best addresses each issue — breakdown maintenance for unplanned stops, preventive maintenance for small stops, or corrective maintenance for defects and yield issues. Methodically working backward from each of the six big losses leads to a direct improvement in OEE.