What is OEE?
OEE stands for Overall Equipment Effectiveness. Essentially, it is a single figure that signifies the utilisation of a machine. This can be at a job level, shift level, overall plant or enterprise level.
Three main OEE factors make up the calculation
They are; Availability, Performance and Quality. These are expressed as a percentage and then the three factors are multiplied together to give you a single OEE figure – again expressed as a percentage.
The point of the final calculation is that it gives you a single figure to measure and compare your OEE. Therefore you may, on a single machine perhaps, compare the OEE between jobs. This will allow you to see which jobs run well and which ones don’t. You can then take corrective action.
You may compare shifts – and gain an insight to whether one shift performs better than another – again you can investigate the underlying reasons and take action to improve the OEE.
You may compare machines within, or across several plants. You may even compare different manufacturing plants where you make similar product and understand underlying reasons why one may have a better OEE than another, and then take corrective action.
The calculation for availability is simply the actual production time, including set up, out of the planned production time. Time that is lost due to downtime through machine failure, lack of input materials, lack of operator(s), as a series of examples, will be set against the calculation.
The next factor, performance, is in theory very simple. It is the actual achieved run rate against the ideal run rate for the machine. Often the machine ideal or optimum run rate may be the figure published by the machine manufacturer.
So the final factor on the overall OEE calculation is quality. This is simply a measure of good product divided by the total product (for the job, shift, day, week etc).
Understanding the theory of OEE is a relatively simple task. Furthermore improving your OEE figure can again be easy. The problem is with collecting accurate data so you know what to act upon.
OEE is an important measure of efficiency and improvements in OEE have a direct positive effect on the bottom line –getting a greater return on investment (ROI) by understanding it and improving it.
Often it is simply getting consistent and accurate data from the existing plant control systems that are the key to a successful OEE measurement implementation, extracting data from various PLC systems is where Simonswood Automation’s expertise can help, together with selecting and configuring the correct software for the OEE visualisation.