OEE calculation with formula

In order to calculate the OEE, the three factors availability factor, performance factor and quality factor must be determined and multiplied together.

1. Calculate the availability factor: Divide the actual uptime by the planned production time.
2. Calculate the performance factor: divide the actual amount produced by the theoretically possible amount (based on the maximum production speed).
3. Calculate Quality Score: Divide the number of error-free units by the total number of units produced.
4. Multiply the three factors together: Availability Factor x Performance Factor x Quality Factor = OEE.

Example of OEE calculation

For example, suppose a production plant has the following data:

• Planned production time: 480 minutes
• Actual operating time: 420 minutes
• Theoretically possible quantity: 2000 units
• Actual Quantity Produced: 1800 Units
• Error-free units: 1700 units

Using the OEE formula, we calculate the OEE as follows:

1. Availability factor: 420 / 480 = 0.875 (87.5%)
2. Performance factor: 1800 / 2000 = 0.9 (90%)
3. Quality Factor: 1700 / 1800 = 0.944 (94.4%)
4. OEE: 0.875 x 0.9 x 0.944 = 0.743 (74.3%)

In this example, the OEE of the production plant is 74.3%.

To calculate the OEE for multiple assets, you should first determine the OEE for each individual asset. You can then calculate the weighted average of the OEE to get the total OEE for all assets. The OEE of each plant is weighted with its respective production volume in order to take into account the different capacities of the plants.

Example: Calculating Overall Equipment Effectiveness for Multiple Assets

For example, suppose we have two production plants with the following OEE values and production quantities:

• Appendix 1: OEE = 75%, production quantity = 1000 units
• Appendix 2: OEE = 85%, production quantity = 2000 units

To calculate the total OEE for both assets, we use the weighted average:

1. Multiply the OEE of each asset by its respective production volume: Plant 1 (0.75 x 1000) = 750; Appendix 2 (0.85 x 2000) = 1700.
2. Sum up the weighted OEE values: 750 + 1700 = 2450.
3. Divide the sum of the weighted OEE values by the total number of units produced: 2450 / (1000 + 2000) = 0.8167.

The total OEE for both plants is 81.67%.

The OEE calculation for a production line consisting of several plants or machines follows a similar procedure to the OEE calculation for a single plant. To determine the OEE for a production line, you must first calculate the OEE values for each individual machine or plant in the production line. This is done by analyzing the availability, performance, and quality for each machine separately and determining the factors involved.

Once you have determined the OEE values for all machines or equipment in the production line, you can calculate the total OEE of the production line. To do this, multiply the values of the individual machines together. It is important to note that bottlenecks or inefficiencies in a machine or plant can affect the entire production line and affect the overall metric.

Example: OEE Calculation of Production Lines

For example, suppose a production line consists of three machines with the following OEE values and production quantities:

• Machine A: OEE = 80%, production quantity = 500 units
• Machine B: OEE = 90%, production quantity = 1000 units
• Machine C: OEE = 85%, production quantity = 750 units

To calculate the total OEE of the production line, multiply the values of each machine together:

Total OEE = 0.8 (machine A) x 0.9 (machine) B) x 0.85 (machine) C) = 0.612

The total OEE of the production line is 61.2%. This value indicates how efficiently the entire production line is operating compared to its theoretical performance potential. In order to further increase the productivity of the production line, OEE analysis can be used to identify and implement targeted improvement measures. These include, for example, the optimisation of maintenance and set-up times, the reduction of downtimes or the improvement of production speed and quality.

Differences

Although OEE calculation is an effective tool for measuring equipment efficiency, there is another metric called Total Effective Equipment Performance (TEEP). TEEP is an extension of OEE measurement and takes into account asset availability in the context of all available time, including planned and unplanned downtime.

The main difference between OEE and TEEP is that OEE focuses on actual production time, while TEEP evaluates plant efficiency in terms of total available time. TEEP thus shows how well a plant utilizes its capacity throughout its uptime, while OEE only measures efficiency during production time.

The TEEP formula is based on the OEE formula and adds the so-called “load factor”, which reflects the ratio of production time to available time. The TEEP formula is:

TEEP = OEE x Utilization factor

When to use OEE and when to use TEEP

The decision depends on the specific needs and goals of your business. OEE is well suited for identifying areas for improvement within production and is helpful in identifying bottlenecks or inefficiencies during production time.

TEEP, on the other hand, provides a more comprehensive view of plant efficiency and also takes into account the time available outside of production. This can be helpful in identifying areas for improvement in terms of overall asset utilization, such as optimizing shift schedules or making more effective use of machine downtime.

Overall, you should use OEE if you want to focus on improving productivity during actual production time, while TEEP is better suited to assess the overall performance potential of the equipment and maximize the utilization of the available time.

Difficulties and pitfalls

Although OEE calculation is a valuable tool for improving plant efficiency, there are some challenges and pitfalls that companies should be aware of:

• Quality: Incomplete or inaccurate data can lead to a distorted picture. Ensure that the data used for the calculation is collected and maintained correctly.
• Uniform measurement methods: To ensure the comparability of OEE values between different plants or production lines, it is important to use consistent measurement methods and definitions for downtime, performance and quality.
• Contextual assessment: Overall equipment effectiveness should always be evaluated in the context of the specific company and production conditions. A high value does not always equate to optimal productivity and in some cases can even lead to excessive plant load.
• Avoidance of “OEE tunnel vision”: Overall Equipment Effectiveness is just one of many metrics that can be used to evaluate plant efficiency. Avoid focusing solely on OEE values and also consider other aspects such as energy efficiency, employee satisfaction, and environmental impact.

How to overcome these challenges

To overcome the above-mentioned challenges in OEE calculation, companies should take the following steps:

• Data management: Implement effective data management processes to ensure the quality and accuracy of the data used to calculate OEE.
• Standardization: Develop enterprise-wide standards and guidelines for measuring and evaluating OEE scores to ensure comparability and consistency of results.
• Continuous Improvement: Leverage OEE as part of a broader approach to continuous improvement and integrate it with other metrics and analysis methodologies.
• Employee involvement: Create awareness of the importance of OEE within the organization and encourage active employee participation in improving plant efficiency.