Overall equipment effectiveness

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Overall Equipment Effectiveness (OEE) - that is, total equipment efficiency, it is an indicator that allows the producer to evaluate the machine's efficiency. Thus, the percentage shows how many machines have made what theoretically they are able to do. This indicator consists of three parameters: accessibility, efficiency and quality. It is calculated using the formula: 

 OEE = availability x performance x quality x 100%

This indicator is the basic measure in the Total Productive Maintenance system, which helps maintain the highest efficiency of machines.

OEE history

OEE was first described in the book Seiichi Nakajima "TPM tenkai" in 1982. At the end of the 80s The 20th century the concept of TPM has become more and more popular among others thanks to Productivity Press publishing the English translation of Nakajima books. This led to the use of the TPM method outside Japan. The OEE index used in the TPM system was calculated to eliminate losses in the production process. In 1995. SEMATECH has published "Semiconductor Manufacturing Productivity Overall Equipment Effectiveness (OEE)" [1], where guidelines for the implementation of OEE were in. At present, this indicator is used around the world in virtually any type of production process.

OEE parameters

Availability

Availability includes loss of availability, i.e. all events that stop further production for a period of time. Includes unplanned interruptions (e.g. failures) and planned (e.g. changes).

Performance

Performance takes into account the loss of performance, that is all the factors that make production run slower than the maximum speed at which it can work. It includes small breaks as well as slow cycles related to, for example, starting machines.

Quality

Quality takes into account the loss of quality, i.e. those manufactured products that do not meet the quality standards. It includes production recovery as well as reduced performance when starting the machine.

Six great losses

In order to be able to specify in more detail what contributes to the largest losses, a specific loss has been assigned to each OEE parameter. They are classified as follows:

Availability Unscheduled breaks Shortage of materials
Performance. Smaller breaks. Speed ​​reduction
Quality Production defects Reduce performance

World Class

The OEE indicator is used all over the world as an indicator for measuring the machine's efficiency. However, the nature of its calculation makes it very difficult to achieve a high OEE score. For example: if all three parameters are 90%, the OEE will be only 73%. Therefore, the "global standard" of this indicator has been set, which is:

Availability 90%

  • 95% efficiency
  • 99% quality
  • OEE 85%

OEE analysis

To effectively calculate the OEE indicator, the following steps should be taken:

  1. Determine the total production time.
  2. Specify the planned production time (taking into account the planned downtime).
  3. Perform an efficiency loss analysis.
  4. Determining the availability indicator.
  5. Determining the performance indicator.
  6. Determining the quality index.
  7. Calculation of OEE - Overall Equipment Effectiveness.

An example of the OEE calculation

Data:

  • Test carried out for one shift - 8 hours, or 480 minutes (total production time)
  • Lunch break - 30 minutes
  • Measured total failure time - 40 minutes
  • Nominal machine performance - 40 pieces / minute
  • Speed ​​losses - 40 minutes
  • Waste - 520 pieces

Schema of task solution:

Determination of the planned production time

working time (length of change) - planned stoppages (break for meals) planned production time = 480 min. - 30 minutes. = 450 minutes

Determining the operating time: planned production time - unplanned downtime (machine failure) operating time = 450 min. - 40 minutes = 410 min

Determining the availability indicator

operating time / planned production time availability = 410 min. / 450 min. 1.

Determination of speed loss

working time with lower efficiency x reduced performance loss of speed = 40 min. x 50% = 20min Working at 50% efficiency is the equivalent of working at maximum efficiency for half the time and downtime for the rest of the time.

Calculation of net operating time

operational time - speed losses 410 min. - 20 minutes = 390 min.

Calculation of the performance indicator

net operating time / operational time efficiency = 390 min. / 410 min. 1.

Determination of qualitative losses

number of defective products / performance quality loss = 520 pcs / 40 pcs./min. = 13 min

Calculation of the effective production time

net operating time - quality losses effective production time = 390 min. - 13 min = 377 minutes

Calculation of the quality index

time of effective production / operational time net quality = 377 min. / 390 min. = 96.7%

Calculation of the OEE indicator

availability x yield x quality OEE = 91,1% x 95,1% x 96,7% = 83,8%

RESULT: Total Equipment Effectiveness for an 8-hour change in the plant is 83.8%.

Data collection methods

To calculate the OEE indicator, collect data, process it, and then prepare the results. These processes can be carried out in many ways using, among others (W. Mazurek 2014, pp. 12-14)

  • The "paper" method
  • The method of manually supported software
  • MES (Manufacturing Execution System)
  • Golem OEE SuperVisor Next - a simple MES system
  • Andon system
  • OEE calculator

Advantages of Overall equipment effectiveness

Overall Equipment Effectiveness (OEE) is a metric used to measure the total efficiency of a machine. It has many advantages, including:

  • Increased production output - OEE helps to identify which machines are operating at the highest efficiency, allowing for increased production output and improved profits.
  • More accurate forecasting - OEE can provide producers with detailed data about their machines’ performance, which can then be used to make more accurate forecasts about future production output.
  • Improved machine maintenance - OEE can help producers identify when a machine is beginning to wear down, allowing them to schedule maintenance before the machine fails and production is disrupted.
  • More efficient use of resources - By understanding the efficiency of their machines, producers can better allocate resources to ensure that they are being used as efficiently as possible.
  • Enhanced customer satisfaction - OEE can help producers provide higher quality products more quickly, leading to improved customer satisfaction.

Limitations of Overall equipment effectiveness

Overall Equipment Effectiveness (OEE) is a key performance indicator that helps producers measure the efficiency of their machines. However, there are several limitations to OEE that should be taken into consideration. These include:

  • OEE does not consider other factors such as quality, service, cost, or safety. It only measures the total efficiency of the machines and does not factor in other important aspects of the production process.
  • OEE is a measure of the overall efficiency of the machines and does not provide a detailed breakdown of which machines are performing better or worse than the others.
  • OEE does not take into account any external factors that may be affecting the production process, such as supplier issues or market conditions.
  • OEE is a backward-looking measure and does not take into account future trends or potential opportunities.
  • OEE can be difficult to measure accurately and is subject to errors, especially when relying on manual data entry.
  • OEE does not provide a direct measure of the profitability of the machines or the production process.

Other approaches related to Overall equipment effectiveness

Here are some other approaches related to Overall Equipment Effectiveness.

  • Total Productive Maintenance (TPM): This approach is used to maximize equipment effectiveness by focusing on proactive and preventative maintenance, as well as establishing ownership of equipment by operators.
  • Six Sigma: This approach focuses on reducing defects and improving process efficiency by identifying the root cause of problems and implementing measures to prevent them from occurring in the future.
  • Lean Manufacturing: This approach seeks to maximize value for customers by reducing waste and streamlining production processes.
  • Autonomous Maintenance: This approach is used to reduce maintenance costs by empowering operators to take ownership of their own equipment and perform basic maintenance tasks.

In summary, other approaches related to Overall Equipment Effectiveness include Total Productive Maintenance, Six Sigma, Lean Manufacturing, and Autonomous Maintenance. Each of these approaches focuses on different aspects of production, such as reducing defects, streamlining processes, and reducing maintenance costs.


Overall equipment effectiveness — recommended articles
Quality cost — Maintenance strategy — Statistical process control — Line balancing — Productivity report — Single minute exchange of die — Quality control — Scrap rate — Assignable cause

References

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