Overall effectiveness of the equipment
Overall effectiveness of the equipment (Overall Equipment Efficiency — OEE) — the indicator allowing to estimate in a complex efficiency of creation of production process except for entrance and output logistics. The term is offered in the late sixties the last century by Seiichi Nakajima, but began to be used outside Japan only in the late eighties
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Determination of value of this indicator comes down to the relation of number of the made products to number of products which could be made for the same time in ideal conditions on the ideal equipment or in other words — to calculation of percent of the actual operating time of the equipment during which it releases a qualitative product.
One of the most widespread approaches to observation is comparison of an indicator of OEE with some target value. For operational management of equipment downtimes, probably, it is better to use the indicators reflecting self-produced specifics. The analysis of the reasons of inefficiency includes three main stages: data collection, data analysis and development of the program of increase in efficiency.
Formula for calculation of OEE
OEE = Availability the X Speed is X Quality
- Availability: is defined as the relation between the actual time of production and the planned time.
- Speed is defined as the relation between actual production speed to rated speed.
- The quality is defined as the relation of quantity of the made products, excepting defects and a total quantity of products.
The indicator of OEE is represented in two formats: digits and percent. OEE in the form of digits are the measured reasons of the arising losses grouped in certain, depending on equipment type, to categories. Percent — the calculated indicator, relative value for a certain time span.
Best value of OEE
The indicator of OEE is used for identification of the losses arising both on separate installation and on a production line, and allows to monitor the happening improvements/deteriorations for a certain period. Deterioration in OEE value can indicate the hidden or not used power of technology process. Control of OEE values can bring impressive results. According to the report of 2003 from ARC Advisory Group, on project deliverables of performance improvement of production of Kraft company using OEE, executed by Rockwell Automation, "lines with full-fledged functionality of OEE provide economy of funds for 2-3 % big, than similar without OEE". The average indicator of OEE at manufacturing enterprises is 60 %. Specialists consider best value of an indicator of OEE more than 80 % for digital processes and more than 85 % for continuous. Respectively, if at the enterprise an indicator of OEE:
- less than 65 % — mean to the enterprise the help is urgently necessary.
- from 65 % to 75 % — it is satisfactory, but there is an essential not used reserve.
- more than 75 % — the good result, however and in this case is opportunities for improvement.
The reasons influencing reduction of a measure value of OEE
- Load time (planned time): a set-up time to production process start, including readjustment of the equipment, the period of loading of information, unplanned stops on check of the equipment, personnel and quality.
- Time during which production is not planned by the diagram. Includes planned stops for maintenance of the equipment, planned meetings, time for release of pilot batches (if this product is not going to be sold), planned training (if at the same time not to be made a product), time off — holidays and the days off.
- Quantity of a defective product.
- Stop time — both planned, and unplanned time.
- Operation of the equipment with lower speed, than it was expected for production of a product of this size and a format. This downtime which represents a difference between the required time and time which is actually spent for production of a product.
Software solutions for management of equipment downtimes
- BAAN system.
- Merit system.
- Wonderware OEE system.
- SIMATIC IT system.
- the Web Navigator system in structure SCADA- systems WinCC.
Optimal use of fixed assets allows to increase the market value of actions, to manage profitability of production process, to promote considerable cost reduction and increase in profit, and, therefore, and to business competitiveness growth.
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