Page 98 - TPM A Route to World-Class Performance

The TPM improvement plan 79

1 Restore before improve.
2 Pursue ideal conditions.
3 Eliminate minor defects.
4 Prevent causes of dust, dirt and scattering.
5 Ask why five times:
0 Why don’t we know the true consequences of failure (both obvious
and hidden)?
0 Why does this part of the process not work as it is meant to?
0 Why can’t we improve the reliability?
Why can’t we set the optimal conditions for the process?
0 Why can’t we maintain those optimal conditions?

5.1 Measurement cycle

Step 1 Equipment history and performance record
This is the essential prerequisite to the OEE calculation (Step 2) because it
records the recent effectiveness of an equipment item. This forms a basis for
the problem prevention cycle (see later).
Included in this record are:
0 data on equipment availability, performance and quality to enable OEE
to be calculated;
0 records of problems and breakdowns as a basis for problem solving and
as evidence of improvements resulting from refurbishment and ongoing
asset care;
0 measurements and records of pressure, noise, vibration and temperature
to show up any adverse trends. Under this heading will come data
collection and data analysis from condition monitoring equipment.
All of this information will have a direct bearing on the ongoing asset care
and improvement programme.
A typical equipment history record is shown in Figures 5.2 and 5.3, and
records of this type will form the basis of the OEE calculation described
below.

Step 2 Overall equipment effectiveness
The OEE formula is at the heart of the TPM process. It is soundly based on
measurable quantities and enables progress to be quantified as the organization
embraces TPM with all its implications. The formula enables calculation of
two parameters:
0 Actual effectiveness of the equipment, taking into consideration its
availability, its performance rate when running and the quality rate of
the product produced. All of these are measured over a period.