Maintenance of production plant leads to the improved availability of such systems. On the one hand there is pure repair maintenance, i.e. which is only carried out when the system has broken down or when minor faults provide indications of possible failure. For some components, this can still be the best solution. On the other hand, it is becoming increasingly necessary to undertake repair measures before damage actually occurs. In the case of cars, inspections are carried out and certain parts replaced on the basis of mileage or the time interval between servicing. The same procedure should also be considered for induction furnace systems and the relevant system components, in order to avoid unpleasant surprises. For this reason, some companies have introduced preventive maintenance. Depending on the level of utilisation of systems, maintenance work and checks are carried out with a view toward maintaining availability of the system. Certain parts are replaced as a preventive measure, irrespective of their actual condition, so that unforeseeable or unavoidable breakdowns cannot occur. This can include for example the replacement of an induction furnace coil after 5, or even after 3 years of operation. Depending on the condition of cooling water hose surfaces, it may prove necessary to replace such hoses prematurely even after very short operating times. The firm of ABB introduced a system of preventive maintenance by means of checklists as early as the mid-1970’s. In this process, as for a car undergoing a road test, the whole system and all its components are inspected, from the furnace transformer to the casting spout, and the further procedure or necessary repairs established. Some foundries have these checks carried out every year in the period up to April, so that the necessary measures can be taken during or even before the company holidays.
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