What is OEE ? Definition, calculation

Within the framework of continuous improvement processes, the OEE is an industrial indicator key that allows the identification of losses. It can be measured in real time using Astn’go MES software.

OEE : the key indicator

Any production process depends on several parameters, which are themselves impacted by physical, technological and human factors. In order to be able to manage these processes, it is necessary to have reliable and relevant information. In this sense, indicators are essential tools for all managers who wish to achieve their objectives.

In order to respond to the need to improve production processes, and to make the necessary corrective and preventive decisions, the Overall Equipment Effectiveness has become the most widely used indicator in the industry. Its main advantage is that it represents the production efficiency of the company in a synthetic way.

Thus the standard NF E 60-182, published by the AFNOR, defines the OEE as the ratio between the fully productive time (time during which the means of production produces good parts at the right speed) and the planned production time (engagement time of the means of production).

Overall Equipment Effectiveness calculation

One method of calculating the OEE is the product of 3 rates :

• Availability
• Perfomance
• Quality

OEE = Availability x Performance x Quality

Each of the rates being the ratio between 2 values, they need to be measured.

The availability rate identifies the operating percentage of the means of production compare to the commitment range. In other words, it is a measure of operating time and downtimes.

The OEE identifies the ratio between the production speed to the theoretical speed (standard cycle time or maximum speed). It is necessary to measure the operating time but it is also relevant to measure the execution speed.

To carry out these measurements, it’s easy with Astn’go whatever your means of production type:

• Counting products, parts and boxes produced
• How Astn’go measures lengths or volume
• Follow and monitor the working time of the machine
• Follow the quality of the production

Losses

Above all, the OEE seeks to identify all the causes of productivity losses. To identify these loss factors, we compare the actual production rate of the production tool with the maximum speed of the same tool. Thus, the remaining delta is the result of all the losses reasons.

The most common one is scraps. They correspond to products that are discarded from the production cycle because of a lack of conformity. This is called non-quality.

Another form of losses, the most common one suffered by industries, is the production downtime. Tihs downtime is disadvantageous because it occurs during the planned production time, known as unplanned downtimes. Those unplanned downtimes can be induced downtimes: lack of supply, lack of personnel, lack of energy… And proper downtimes: downtimes, adjustments, controls, maintenance, tool changes… This is called non-availability.

Finally, production is very frequently subject to rate variations, observed between the maximum speed and the actual production speed. These variations can be explained by under-steering, micro-downtimes that are difficult to measure and sometimes under-productivity of the operators. This is called non-performance.

MES and OEE

In the effort to improve OEE, it is imperative to digitalize shop floor. This digitalization allows a fast and effective follow-up of all the industrial performance factors. Industries in the process of digitization are required to integrate a software able to organize their means of production in real time in a digital manner. This is known as Industry 4.0.

The MES (Manufacturing Execution System), is a production management tool that collects data from the entire production in real time through operators reports, or automated data collection via IIoTs (Industrial Internet of Things).

These collected data, then, are consolidated and verified. For example, to set up indicators measuring the performance loss reasons in the shop floor. They allow a daily production follow-up. The MES software allows an optimization of the resources needed for the production. Indeed, it reduces losses due to non-quality, non-performance and non-availability. It will also offer an tracking of all the daily actions, and all this while aiming at the “Paperless office”.

The use of the MES software Astn’go leads to continuous improvement actions with the objective of increasing the OEE.

Continuous improvement process

Continuous improvement is an industrial structured approach, which aims to increase industrial performance. One of its main characteristics is its regular activity. It is a cyclical approach known as “small steps”. This means that at the end of progress and objectives cycles, reached, will serve as a basis for the next cycle.

Continuous improvement draws its principles from Deming’s PDCA model. Commonly called the Deming wheel, the PDCA method (Plan, Do, Check, Act) illustrates the restart, to which is added a shim. This shim represents the validation of the achievements made during the last cycle. It allows the wheel not to go back down. There is therefore a perpetual movement improving the process at the end of each cycle, it is the principle of continuous improvement.

This approach allows to reduce costs, malfunctions, scraps, time per unit produced and to improve overall performance.

Among the continuous improvement methods facilitated by the integration of Astn’go software, there are :

• SIM : Short Interval Management. By automating the collect of data, strengthening them and proposing display media on the desired screens.
• Visual management : Astn’go software offers a dedicated environment for visual management. Thanks to complete dashboards, customizable widgets, intuitive presentations and a high quality digital support.
• Smed : A method that has proven itself in industry. SMED seeks to optimize the tool change and to reduce losses related to adjustment time. This is why Astn’go measures changes and adjustment times. It provides real time indicators for operators and managers.

There are many other continuous improvement methods facilitated by the use of a MES software.