New furnace linings from expert hands
The heat-resistant furnace lining of melting and dosing furnaces makes a significant contribution to their efficiency and product lifetime. Thanks to a sophisticated relining concept in OEM quality, the StrikoWestofen frequently achieves characteristic values comparable with those of the latest generations of furnaces. “Work done incorrectly shortens the service life of the equipment, reduces the melting capacity and increases the energy consumption by up to 30 percent,” explains Holger Stephan, manager of the “Service and Spare Parts” department at StrikoWestofen. “Furthermore, additional cost-intensive and time-consuming work is often necessary – like operating dosing furnaces with porous plugs.”
Refractory linings of melting and dosing furnaces are high-tech nowadays. The materials, including six different types of refractory and insulating materials, as well as the entire interior furnace geometry are precisely engineered and constantly optimized.
Engineered process guarantees success
In the context of the relining of melting systems, StrikoWestofen offers a complete engineering service which achieves optimum results. In a first step, the service technicians record the current performance and energy consumption of the furnace under real foundry conditions. On the basis of this assessment, StrikoWestofen compiles a forecast of the values to be expected after the complete renewal of the lining. “The use of state-of-the-art materials and the latest engineering results often allow us to achieve values comparable with those of up-to-date models – at only 20 percent of the purchase price,” Holger Stephan explains. “On the premises of our customer Skoda Auto a. s. in the Czech Republic, we were able to reduce the gas consumption per tonne of molten material by 40 percent from 102 to 61.2 cubic meters by relining the furnace and training employees in a targeted way. In terms of the annual melting performance at the Mladá Boleslav location, the costs for lining a total of four melting furnaces are rapidly recouped after only ten months,” Stephan explains. Relining is not just maintenance – it is a permanent improvement of the original system as well. Once relining has finished, StrikoWestofen validates the forecast values in a field test conducted on the customer premises, thus guaranteeing optimum results.
Don’t save in the wrong place
Service lives of ten years and more are not unusual for furnace linings from StrikoWestofen. This durability is based on the exact planning of the materials used as well as angles and gradients inside the furnace. Areas undergoing particular stress are therefore lined with especially resistant refractory material and the angle of flow is optimized in order to minimize the load on the materials. However, even the most well-planned lining must be replaced at some time. Small repairs are made in situ by trained service personnel.
Westomat dosing furnaces: the crucial difference
If it becomes necessary to completely reline the dosing furnaces, it is not a good idea to do so on the customer premises, although this is in fact common practice. The problem is that all of the subsequent steps have to be taken on the customer premises as well. In particular, however, the correct drying of the fireproof lining is of crucial importance for reliable operation. If drying takes place at the foundry, it can only be done via the heating rods built into the furnace. This puts a heavy load on the heating rods and the customer has to bear the costs for the necessary electricity. In addition, foundry operation is permanently disturbed for several days. “For this reason, we are offering a totally different concept. The furnace bodies are removed and taken to our factory, where they are completely revised,” Stephan explains.
Relining in the factory
In the factory, the body of the furnace is tested for pressure tightness and the lining is renewed. The refractory material is dried in a drying chamber specially designed for the purpose. The advantage of this is that no strain is put on the heating rods. Also, the stay in the chamber guarantees that the refractory dries completely with no residual humidity. The humidity could otherwise precipitate in the melt in the form of hydrogen, contaminate it and, in the worst case, even cause a hydrogen explosion. Costly and time-consuming initial operations with porous plugs can thus be avoided. At the same time, the drying process takes only one third of the time required for drying in situ. In this way, the furnace can be taken into operation in the foundry more swiftly. Regular heating is sufficient.
To compensate for failure in foundry operation, StrikoWestofen also offers a special service. The equipment manufacturer has a portfolio of Westomat dosing furnaces which can be provided for the duration of the relining process. This allows operation to continue with a minimum of disruption.