Overall equipment effectiveness

The concept of overall equipment effectiveness ( OEE ) or English Overall Equipment Effectiveness (OEE ) denotes an index created by the Japan Institute of Plant Maintenance. She is one of the results in the wake of decades of development of the TPM concept ( TPM: Total Productive Maintenance). The overall equipment effectiveness is a measure of the value of an investment.

The GAE a plant is defined as the product of the following three factors:

  • Availability factor,
  • Performance factor
  • Quality factor.

Your values ​​range between 0 and 1 or between 0% and 100 %.

Measure, its definition can be found in any standard. It is very tailored individually to the -applying companies. This is usually a prolonged process because the company only understand the way of thinking in the categories of value and waste must be built. Furthermore designed depending on the equipment or products, the acquisition of the necessary basic data for the determination of the ratio may be difficult. Many companies therefore rely on special software for data collection, evaluation and analysis. The overall equipment effectiveness results together with the overall service efficiency (OSE or English jumpsuit Service Effectiveness) the overall administration Effectiveness (OAE ) of a company.

Overview GAE

The GAE is a measure of unplanned losses of an investment. Therefore, be deducted the planned shutdowns in the first step of the calendar time ( a week 24 hours, 7 days ). Planned downtime can be, for example:

  • No occupation / Instrumentation
  • Planned maintenance
  • Break
  • Strike
  • Etc.

The remaining operating time is the basis for the GAE and is therefore defined as 100%.

Of these, 100 % now the performance, availability and quality losses are deducted, thus resulting in the GAE of the plant.

Availability factor

The availability factor is a measure of losses due to unplanned plant shutdowns. It is defined as follows:

The availability factor is reduced due to unplanned plant shutdowns such as the following events:

  • In the short term lack of staff
  • In the short term missing material
  • Missing Production Order
  • Waiting for maintenance
  • Waiting for quality releases
  • Power failure
  • Etc.

In business, a convention must be made as to when there is an unplanned stop. To capture every second deadlock and also establish, in most companies is too high a cost. In operational practice, a detection limit of 1 minute has shown downtime as a pragmatic approach. All shutdowns over a minute to go with it in the power factor.

Whether Upgrade reduces the GAE, is a matter of company-specific definition. Reduce the GAE setup activities, creates a motivation to reduce setup time by SMED ( Single Minute Exchange of Die ). On the other hand, this also means that a GAE enhancement can be achieved by less conversions, ie with larger batch sizes. This is contrary to the principles of lean production. Reduce setup activities not GAE, there is a risk that disturbances are declared as set-up process, which are actually not.

The best way to deal with set-up times is to work with Rüstzeitvorgabewerten. The proposed set-up time does not reduce the GAE, but Rüstzeitüberschreitungen they reduce. However, this purpose must Rüstzeitvorgabewerte be distinguished when required for different setup options, available. The expense of this is very large may.

The availability factor is recognized frequently by the three OEE factors easiest. Therefore GAE initiatives start in business often with the detection of the availability factor.

Power factor

The power factor is a measure of losses due to deviation from the planned target time, smaller failures ( ie the shutdowns that are not included in the availability) and idle times.

It should be noted that the power factor only with respect to the runtime and can not be calculated on the operating time.

While the actual performance is measured, it is often difficult in practice to arrive at a target power as the default value. If no machine manufacturer's available or are not realistic, the concept has proven " bestdemonstrierten piece of time." The production rates of the products from the past are compared and the highest production speed is defined as the desired performance in terms of 100 % power factor. However, the power factor obtained in this way is not suitable for production programming. The factor 1 constitutes a peak value which would not regularly achieved.

For plants that produce only one or a few products, the calculation of the power factor is simple. If a variety of different products running on a system, the cost of determining a set time is high under certain circumstances.

Quality factor

The quality factor is a measure of the loss due to defective and to working parts. It is defined as follows:

In particular, in the collection of the quality factor, a pragmatic approach is useful: Frequently insufficient quality is not detected on the system, it has caused. Here it has been proven, the " discoverer " principle to use, so burdening the system with a GAE - reduction, where the error was detected. Thus, the GAE from a pure plant and becomes a process code. The optimization of the GAE a system can of course also take place by tweaking other installations. The GAE should be current as possible code. As such, the iO - determined amount should not later than the loose end and the GAE are calculated. From subsequent corrections of the GAE eg by subsequent closures is not recommended.

Overall plant efficiency

Overall system efficiency and overall equipment effectiveness is used synonymously in the German language, even if this is not correct (see effectiveness).

Overall Equipment Effectiveness

The GAE is defined as a product of availability factor, power factor and quality factor. So follows:

The result is a percentage value that indicates is how much of the planned machine time actually produced. This value is usually significantly less than 100 %, since the influent factors also usually are each less than 100 %. Thus, the variety of wastes are made ​​clear.

Benefits of GAE

The benefits of GAE is the transparency of the value share of the plant, leaving the management with a different view of the plants look. The index is ideally suited to, for example, to establish a target agreement process to a GAE increase because the code can be made due to their comprehensiveness robust to structural changes in production.

Increase in the GAE

For the targeted increase in the GAE the reasons for deviations of the GAE factors must be covered by 100 %. So the question is, why was not

By a manual or system-based detection (eg in the data acquisition or by independent IT solutions ) of the deviations from the defined ideal state, an analysis of the Pareto distribution of the largest sources of loss for a plant can be generated. Hence measures targeting the improvement of the GAE can take that can then be measured. We start the optimization with the source of the greatest GAE loss.

Practical experience

  • An agreement reached in practice GAE of 85 % can be classified as "very good". It is here to differentiate about which types of plant / production mechanism is involved. So can also serve as a lower limit of 90 % at a GAE Vollkonti system, however, can be a GAE of 60 % should be a cap on a difficult -to-handle production.
  • Particularly in the case of several interlinked without buffering systems a GAE of the overall system, for example, 85 % is difficult to achieve, since the calculation by multiplying the single - gaes done (Ex: 3 interlinked plants, each with a GAE of 90 % lead to a OEE of the overall system of 0.9 × 0.9 × 0.9 = 0.73 )
  • For multiple concatenated with buffering systems, the correct GAE detection can be performed only IT technology with several measuring points. Each measuring point is required in addition to the Standardstörgründen nor the Störkategorien "Jam " and " demolition " to identify upstream and downstream disturbances of production can.
  • The determination of GAE caused, especially in the early days a lot of effort on the one hand by the training staff and the other in the production of genuine data.
  • The GAE can not be used to measure the performance of employees. It is used for identification and measurement of investment losses, which can then be eliminated by appropriate root cause analysis and action.

Accruals

The GAE is not to be equated with other metrics that are commonly recognized in the production or maintenance, such as

  • Technical availability

Literature

Independent OEE literature:

  • Koch, Arno: OEE for the production team. The complete OEE User Manual - or as you discover the hidden machine. Ansbach: CETPM Publishing, 2008, ISBN 978-3940775047.
  • May, Constantin; Koch, Arno: Overall Equipment Effectiveness (OEE ) - tool to increase productivity, published in: Journal of Consulting ( ZUB ), H. 6/2008, pp. 245-250. for download from the Centre of Excellence for TPM ( CETPM ) (PDF file, 190 kB)
  • Oee for Operators: Overall Equipment Effectiveness, Productivity Development Team, Productivity Press, 1999
  • OEE, Inc., Jesse W. Brogan, The Management Upgrade Shop, 2004

In TPM literature:

  • The TPM fibula, JIPM, Publisher: Wolfram means Häußer, Adept - Media -Verlag, 2013, ISBN 978-3-98072765-5 [ S.46ff. ]
  • TPM - efficient maintenance and equipment management, Edward Hartmann, Landsberg, Modern Industry Publishers, 2000 [ S.77ff. ]
  • Introduction to TPM, Seiichi Nakajima Productivity Press Cambridge Massachusetts, 1988 [ S.27ff. ]
  • Total Productive Maintenance, Al - Radhi, Carl -Hanser- Verlag, Munich, 1995 [ S.30ff. ]
  • Total Productive Maintenance - The Western Way, Peter Willmott, Butterworth -Heinemann Ltd, 1994 [ S.25ff. ].
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