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Common accidents involving medium-frequency furnaces include furnace leakage and melt-through. If no measures are taken when an accident occurs, the coil copper tubes could rupture, and the contact between molten iron and coolant could trigger an explosion. Let’s take a look. Medium-frequency melting furnace The cause of the leak.
1. Quality factors of furnace lining materials: Generally, acid-resistant furnace lining materials made of quartz are used. Quartz sand and quartz powder should contain more than 99.5% silicon, with crystalline structure, transparency, and free from impurities.

II. Factors Affecting the Use of Binders in Furnace Construction: Traditionally, boracic acid has been used as the binder in furnace construction. Boracic acid has both advantages and disadvantages: its advantage is that it provides rapid bonding at low temperatures—typically starting from 600 to 700 degrees Celsius—but its disadvantage is that it lacks resistance to high temperatures and corrosion. Under high-temperature conditions, the lower part of the furnace wall may experience "scouring," significantly reducing the number of times the furnace can be used. It is recommended to replace boracic acid with boron anhydride as the binder, since boron anhydride boasts characteristics such as high-temperature bonding, a high melting point, resistance to high temperatures, and resistance to corrosion.
3. Factors Affecting the Proportion of Materials Used in Furnace Construction: Typically, users mix the materials themselves, and during the mixing process, workers fail to follow the correct proportions, resulting in uneven furnace lining material with insufficient density. This leads to a shorter service life for the furnace lining—generally around 40 to 50 heats. It is recommended to use prefabricated furnace linings prepared by professional furnace lining manufacturers. Features: Consistent material proportions, uniform mixing, high density, and a furnace lining lifespan that is 1 to 2 times longer than that of manually made linings.
4. Site factors in furnace lining preparation: Typically, when users prepare furnace linings themselves, they lack a dedicated preparation area. During the lining preparation process, impurities such as iron filings and beans can easily get mixed in, significantly reducing the number of furnace batches that can be produced. It is recommended to use furnace linings manufactured by professional lining producers. Features: Professional production workshop with no sale of ferrous materials or other impurities like iron filings and beans.

5. Raw Material Factors: Currently, raw materials are in short supply and prices have risen. To cut costs, some enterprises have been purchasing raw materials—such as iron beans, iron scrap, and washed materials—at low prices. These materials often contain impurities, which severely erode the furnace lining and significantly shorten its service life.
Six. Medium-frequency electric furnace Inherent factors related to charging: The medium-frequency induction furnace combines charging with an induction coil. The furnace shell is divided into left and right sections, connected by eight stainless steel screws and several asbestos gaskets. During operation, these eight stainless steel screws must remain tightly fastened; the asbestos gaskets are absolutely essential. If the screws become loose, the furnace shell will twist back and forth when molten iron is discharged, causing the induction coil to warp and the furnace lining to loosen and crack, allowing molten iron to leak through the furnace chamber. Solution: Replace the asbestos gaskets and tighten all eight screws.
7. Induction Coil Factors: The induction coil is wound from a copper tube into several turns, with each turn containing 5 to 8 copper screws connected by insulating bakelite. During operation, the copper rings should never be missing any screws. Once the induction coil loses even a single screw, electromagnetic vibration forces will develop, continuously impacting the furnace lining and causing it to loosen and crack, ultimately leading to molten iron leaking through the furnace interior.
8. Insulating Bakelite Component: The insulating bakelite is located at the connection points between the turns of the induction coil. When molten iron is tapped out, the insulating bakelite supports the weight of the entire induction coil, the furnace lining, and the molten iron itself. Once the load-bearing capacity of the insulating bakelite is exceeded, it will bend, causing the furnace lining to loosen. Cracks typically appear at the junction between the back wall of the furnace and the furnace bottom, leading to molten iron leakage and eventually resulting in a "furnace breakthrough" phenomenon. Solution: Each piece of insulating bakelite is connected to the furnace shell using brickwork, thereby integrating the furnace shell with the induction coil and enhancing the stability of the induction coil, which in turn extends the service life of the furnace lining.
9. Gap Coefficient Between the Furnace Shell and the Induction Coil: Most medium-frequency induction furnaces used by standard manufacturers come in capacities of 0.5 ton, 0.75 ton, 1 ton, 1.5 ton, 2 tons, 3 tons, and so on. However, some manufacturers, in an effort to increase production, have increased the capacity of their induction coils—from 0.5 ton to 0.75 ton, and from 0.75 ton to 1 ton—thus reducing the gap between the induction coil and the furnace shell. During melting, the solution is to replace the furnace with a standard medium-frequency induction furnace (where the typical gap between the induction coil and the furnace shell is 250 mm to 300 mm).
10. Wall Thickness Coefficient for Medium-Frequency Induction Furnaces: The standard wall thickness is 90 mm to 120 mm, while the bottom thickness ranges from 200 mm to 280 mm. However, in order to increase production capacity, some manufacturers have added furnace linings, resulting in thinner walls—reducing the wall thickness to 40–70 mm and the bottom thickness to 150–200 mm. To achieve stable, high output, it is not advisable to build the furnace using the standard wall thickness.