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Anyone who operates a plant has an interest in ensuring that it worksas effectively as possible. However, relatively few enterprises todayare in a position to answer questions such as: Why are capacities idle, or why are they unproductive? To what extent does our actual performance deviate from our performance targets? Why do two apparently identical teams/plants produce qualitatively different products? Are all our resources being exploited efficiently for the product that we actually produce? Overall Equipment Effectiveness (OEE) is the rubric underwhich these questions can be summed up. With the highly automated processes of today, the only reasonable way to determine the overall effectiveness of the plant is by automated methods. Manufacturing ExecutionSystems (MES), which serve as the interface between the ERP (Enterprise Resource Planning) system at the management level and Distributed Control Systems (DCS) at the field level, provide the necessary tools for this. For only when management data are considered together with current production data is it possible to make a real-time statement about equipment effectiveness.
However, manufacturing processes today are as many and varied as today’s products. In order for any statement on overall effectiveness to be useful, the MES needs to be adapted to the properties of the individual production concerned. In orderto do this, very good process knowledge is required as well as experience with MES. Automation and IT experts like the German company Rösberg Engineering have an knowledge of production processes; and know which parameters are really relevant for measuring OEE.
Basically,the OEE is the product of availability, operating ratio and NEE (netequipment effectiveness). Since all three values can never reach 100%– due to the necessary set-up times, apart from anything else – an OEEof 85% is already world class. 80% is realistic; however, according to worldwide studies the average is around 60% at present. Thus there is an enormous potential for improvement. In order to ascertain the effectiveness of an actual machine or plant, specific indicators, known as Key Performance Indicators (KPIs), are helpful.
However, information alone does not solve the situation. In a production process in which many different individual processes interact and several machines are usually involved in numerous production steps, more data are usually generated than can realistically be evaluated by a human beingin a reasonable time. Thus visualization support tools are essential.Data have to be processed and presented in such a way that, for instance, the machine operator or the management can see at a glance where,and why, OEE is not as it should be, in order to initiate effective countermeasures as quickly as possible.
Here, automation and ITexperts like to use the decentral, modular MES solution Simatic IT. This system adapts to the individual requirements of the relevant user.It enables information about OEE, such as e.g. actual operating time versus planned production time, or information on the analysis of downtimes (Downtime Management) to be clearly presented.
By using aManufacturing Execution System, not only can unproductive areas be pinpointed, but savings are made straight away. Up to now orders have been printed out, due to missing ERP interfaces, and brought on paper toproduction. There, the order data have to be entered into the DCS, processed, and then more documentation has to be printed out to be transferred back into the ERP system. It is not difficult to see that this procedure is not only time-consuming, but also error-prone. If the twoareas are linked by an MES, this cuts out completely the labor input and the error sources associated with the printing out and manual recording of information. Throughout the system, only the real production data is present.
By installing an MES, plant operators can also realize compliance with legal requirements that apply in special branches of industry, e.g. traceability. Depending on the needs of the enterprise, Rösberg supports its clients in their introduction of a newautomation solution, from consulting and development.
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