Application of statistics in Maintenance

It often happens to us that we have a lot of data collected in tables and that we have to interpret. An example is the recording of downtimes on different equipment.

We all know that the analysis of data in tables is difficult to do and that is why graphical representations are desirable.

The MINITAB statistical software provides us with graphical and statistical tools that process this data in a form that is easy to analyze. I mention some of the most used: Histogram, Box Plot, Pareto, Time Chart.

The histogram is useful when we want to see the data distribution. The histogram shown in the image shows us that the stops with the highest frequency are 4 minutes and the average of the stops is 4,175 minutes. The goal is to reduce the average of stops, which could be done by lowering the values ​​that are above average.

Box Plot gives us information about outliers and allows the summary display of multiple data sets for a visual comparison. The BoxPlot in the figure shows the shutdown times on two production lines.

We use Pareto when we want to analyze the frequencies of defects. This is a tool that helps us decide on the improvement projects we should implement.

With the time diagram we observe the evolution trend of the defects on the equipment and we can obtain indications regarding their reliability. We use the Time series Plot tool from MINITAB.

Therefore, as can be seen, the application of statistical tools in MINITAB or other statistical programs (eg SigmaXL) can help us in the maintenance activity to have a more accurate assessment of the performance of the equipment we manage.