Quantifying TPM

A significant focus of lean manufacturing Six Sigma is measuring the effects of any program put into place to reduce waste and increase quality. This information is a critical indicator of success, or the need for additional process transformation.

In the case of Total Productive Maintenance, the impact of a pro-active equipment upkeep program must be quantified regularly. Because any lean manufacturing Six Sigma transformation relies upon flexibility, a consistently applied system of metrics is necessary to regularly establish whether or not a manufacturing environment is functioning at peak performance, or if areas of waste exist. Regular assessment is warranted to consider performance in the context of changing economic, equipment performance and workforce conditions.

The Value of TPM Metrics

Regular measurements are a significant part of implementing Total Productive Maintenance. Rather than limit metrics to an examination of production numbers pre- and post-implementation, machine conditions are assessed to make certain equipment is in good working order and able to delivery quality output. These measurements are monitored over time, and any fluctuation is duly noted. Deviation in the value of these metrics allows manufacturers to respond proactively and avoid the risk of operational defects.

Relevant Metrics for TPM

The primary means for quantifying the impact of Total Productive Maintenance is not the number of units produced at a location. This figure is affected by a number of variables and cannot be tied exclusively to TPM efforts. Instead, the Overall Equipment Effectiveness, or OEE, is used. This value specifically targets manufacturing performance in the context of equipment performance. Overall Equipment Effectiveness is based upon three variables, equipment availability (A), performance efficiency (PE) and yield (Q). Equipment availability is quantified as the amount of time a machine is available versus the amount of time it should be available. Performance is measured in terms of speed of operation. Yield is the comparison of total units produced versus the number of quality or workable units. OEE is calculated by multiplying these three variables:

OEE = A x PE X Q

It is important to set a target OEE value, and monitor performance on a regular basis as part of the overall lean manufacturing Six Sigma transformation effort. Variation in the OEE value can indicate the existence of process issues, as this value is affected by:

  • Equipment Downtime
  • Engineering Adjustment
  • Minor Stoppages
  • Unplanned Breaks
  • Time spent producing defective units
  • Waste

When the variation source has been identified, corrective measures may be implemented to return OEE to the target range. This is lean manufacturing Six Sigma put into practice.