The ramming process of the furnace lining in medium-frequency induction furnaces is a critical aspect of furnace body lifespan and melting efficiency. Currently, the main ramming methods are divided into two types: wet ramming and dry ramming. These two processes are suitable for the construction of acidic, neutral, and alkaline furnace lining materials, and the appropriate method should be selected based on specific working conditions.
The core characteristic of the wet ramming process for medium-frequency induction furnaces is the addition of adhesives such as water, water glass, and brine to the furnace lining material for mixing and ramming. The addition of these adhesives provides better plasticity to the material during construction, which not only reduces dust pollution and improves the working environment but also allows for a more regular initial shaping of the furnace lining.
However, wet ramming has significant limitations: firstly, the introduction of adhesives reduces the density of the furnace lining material, leading to a decrease in refractory performance and directly affecting the high-temperature strength of the lining; secondly, the drying process of the furnace lining is time-consuming, extending the equipment preparation cycle; most importantly, the residual moisture inside the furnace lining will vaporize during high-temperature melting, which can easily cause deterioration of the inductor's insulation performance. If not handled properly, it may lead to inter-turn breakdown and fire in the inductor, or even serious accidents such as ground short circuits. Therefore, the wet ramming process is not recommended for large-scale melting medium-frequency furnaces and is more suitable for small experimental furnaces or short-term emergency use scenarios.
The dry ramming method is currently widely used in the construction of crucible-type induction furnaces due to its significant advantages. This process uses a purely dry material ratio, without adding any binders throughout the process, maximizing the retention of the refractory properties of the furnace lining material itself.
The technical advantages of dry ramming are reflected in several aspects: through precise material grading and high-strength ramming, the thickness of the sintered layer of the furnace lining can be significantly reduced, while the powdered buffer layer is correspondingly thickened, effectively reducing heat loss from the furnace lining; at the same time, the internal structure of the dried furnace lining is stable, and the stress distribution is more uniform during thermal expansion, greatly reducing the probability of crack formation. These characteristics collectively improve the reliability of the furnace lining and extend the service life of the furnace body, making it particularly suitable for continuous production medium-frequency melting equipment. In actual production, the dry knotting process should be given priority, especially for large, high-power medium-frequency induction furnaces, as it can significantly reduce the risk of equipment failure and ensure the stable operation of the melting process.
