Starter blocks are needed for starting up induction crucible furnaces of up to approx. 150 Hz operating frequency, so that the furnace can start with an acceptable power consumption and electrical efficiency. The diameter should be approx. 100 mm less than the crucible diameter on relining.
Conicality is required for rapid emptying from the mould. Some customers have made themselves separable moulds, and can therefore work with a very low conicality of below 1%. When casting the starting blocks, the lifting eyes of construction steel are cast directly into the block. In order to prevent damage to the lifting eyes during stacking in the crucible or during storage, it is advisable to create corresponding recesses in the lower area of the starting blocks. With the corresponding design of the mould with 2 lateral grooves, the prefabricated lift- ing eyes are inserted into these grooves and thus adequately held in place. Operators of medium-frequency systems should also keep a number of starter blocks in stock, since these are very helpful for pushing in light scrap or lower- ing the melt temperature for sump smelting.