Melting is the first step for making grinding balls.  Also, there are several different furnaces to melt in the world.   Undoubtedly, medium frequency induction furnace is the most welcomed and functional.

    grinding balls melting furnace


Brief Introduction

Medium frequency induction furnace divides into two big groups, one is aluminum shell, and another is steel shell type. Each type has the capacity from 0.25tons to 5tons with advantages. 

However, if only used for grinding ball project, we usually relate the size of the furnace to the customer’s target annual production so that to reduce the energy wasting and costs. 

For automatic balls making production line, most welcomed furnace size is 1ton, 1.5ton, 2tons. 

For manual metal molds to produce grinding media, 0.35 to 2tons are welcomed according to producing productivity. 

Here is the cleared discriptions between two types of furnaces.

Aluminum Shell Induction Furnace

Aluminum Shell Medium Frequency Induction Furnace consists of Furnace body, Reducer & supporting device, Water-cooled cables, Control panel, Capacitor Box. 

induction melting furnace

Furnace Body

1) Induction coil

The induction coil is in the heart of the entire induction furnace, induction coil from the intermediate frequency power supply generates a powerful magnetic field under the influence of medium-frequency voltage, current, the magnetic metal inside the furnace and eddy current heating coil is the critical power conversion of thermal energy. Coil design, so it is essential for the gifted, the furnace coil is a combination of domestic and foreign intermediate frequency furnace actual use, according to the electromagnetic theory, the preferred option through accurate analysis and calculation determined.

An induction coil with copper pipe
To guarantee the reliability of the induction coil, induction coil used the brand for T2 (purity electrolytic copper 99.5%), 5000KG furnace wall thickness using 6㎜ extrusion rectangular copper pipe on the special die winding and become, it not only ensures the coil rigid and has the most conductive section. The density of copper pipe, pipe wall thickness. Induction coil when the design considering the influence of the inherent and length of copper pipe, the copper pipe welds and electricity, water diversion area, make each group of induction coil inside without welds.

Induction coil of the exterior insulation adopts the binary forms, the inner coating by electrostatic spraying process with a high-strength insulating resin. Then use the class H class insulation paint leaching paint dry.

Induction coil by welding outer circumference series bolts and insulation stay fixed. After the loop is fixed, its turn spacing error is not more than 2 mm. All the countersunk head bolts, in order to improve the dielectric strength

Induction coil welding is made of the silver electrode, does not affect the current liquidity.

2) Furnace frame: composed of primary aluminum and magnesium alloy casting

Furnace frame by two pieces of aluminum semicircle casting furnace. Also, the surface of the upper two pieces of aluminum casting furnace with middle asbestos board, insulation board, and the self-contained stainless copper wire rod, asbestos plate with heat and blocking current generating circuit to make aluminum furnace heating effect, insulation board with insulation and tighten sensors column does not move, make the whole aluminum shell furnace is strong and durable.

Furnace frame part reserved when the design safety coefficient. Ensure furnace frame has sufficient strength, carrying the maximum charge run smoothly. Angle is greater than 95 degrees.

Reducer & Supporting device

Using RZS type reducer. RZS type reducer for especially dedicated reducer, it is mainly used for medium frequency melting furnace, high-temperature furnace automatically dumping operations, mechanization in advance, to ensure the quality of casting to reduce labor intensity and improve productivity play an important role, also can be used for automatic welding, automatic, automated assembly line workpiece transposition etc. Turn the operation requirements.

RZS reducer is the critical product electric furnace overloading, and this product is a secondary drive worm gear and worm reducer, RZS631, input power respectively 3.5kw, this product has small volume, large speed ratio, transmission self-locking, low noise advantages. RZS631 equipped with the manual and electric control device, electrical control with tilting furnace control box contactor three phases electric conversion control motor and reversing a tilting furnace oven, with extension and handle button control. Manual operation, pull a hand wheel and worm gear off the first grade, and movement to secondary worm reducer directly by the handwheel to by the second worm gear drives the output shaft. This product is convenient for installation and commissioning. 

Water Cooling Cables

Copper cable joint by the integrated processing, contacts, good conductive ability, no welding points more firmly substantial deformation; muscular tensile strength.

Capacitor Box

The capacitor box we use is purchased from the famous brand manufacturers which the registered capital more than twenty million. The production of capacitor quality first class, overvoltage ability, in the application process of long term to win the user consistent high praise.

Control Panel

The main components of the control panel, like thyristor, circuit board, and Circuit breaker, we all purchase from qualified manufacturers in the world to ensure the life and working condition for furnaces. We can also use the customer-designed brand for each part. 


Steel Shell Induction Furnace

Steel Shell Medium Frequency Induction Furnace consists of Furnace body, Hydraulic station, Water-cooled cables, Control panel, Capacitor Box. 

Furnace Body

It is adopting steel shell magnet yoke hydraulic transmission structure. It consists of the furnace fixed frame, furnace frame, induction loop, magnet yoke, refractory material, pouring device, water cooling cable.

About the induction coil, this is the key part of the induction furnace. Use reliable and durable high conductivity copper to make, the upper and lower layers of the parallel winding system. Both ends installed the water ring short circuit ring, the induction coil’s surface brush a coat of high-temperature insulating paint, the maximum to avoid the furnace shell fever.
The induction coil is the heart of the whole furnace, which not only directly affects the absorption of the furnace power, its design rationality, and quality also directly affects the lifetime of the lining. The sensor is fixed by the number of bolts and insulated bars in its outer circumference. The upper and lower parts of the loops are installed water-cooled rings, and the purpose is to make the lining material in the axial heating evenly to extend the lifetime of the lining.

Main characteristics of our made induction loop.

A. In the structure, we adopt advanced short-circuit designing. Eliminate the medium frequency furnace’s components of the fever.

B. The traditional designing of induction coil – lining produces weak electromagnetic mixing power. So brushing the bottom of furnace severely, now adopting extended circles to increase the electromagnetic power to improve the lifetime of lining.

melting furnace -induction loop

Control Panel

Medium frequency power supply

Can control medium frequency power supply is AC-DC-AC device. Using thyristor components can change three-phase AC power supply into a single – phase AC power supply. Medium frequency power thyristor rectifier KP and inverter KK thyristor uses the series-parallel connection. Layout cabinet is an easy installation, maintenance, and commissioning. Cooling method adopts water and air cooling.
Each medium frequency power cabinet has two parts: the rectification system and inverter system.

1) Medium frequency power supply (rectification system ) : automatic air circuit breaker, Fast Fuse, Current Transformer, Line Inductor, and Rectifier KP, etc.

2) Medium frequency power supply (inverter system ): Inverter KK, the main control board, commutation inductance, filter reactor…

Filter reactor: reactor, also known as inductance, consists of iron core and water-cooled coil. The filter reactor is installed outside the cabinet and it is connected between the output DC bus of the medium frequency power supply (rectification system) and the input DC bus of the medium frequency power supply (inverter system) through the water cooling cable to stabilize the output voltage and reduce the interference that medium frequency voltage brings to network voltage .

The most significant feature of the reactor made by our company is having a large amount of inductance. So the stability of the electrical system is superior to similar manufacturers; higher harmonic components are lower than comparable products.

power control panel melting furnace

Capacitor Box

The capacitor box we use is purchased from the famous brand manufacturers which the registered capital more than twenty million. The production of capacitor quality first class, overvoltage ability, in the application process of long term to win the user consistent high praise.

Water Cooling Cable

Copper cable joint by the integrated processing, contacts, good conductive ability, no welding points more firmly substantial deformation; muscular tensile strength.

Hydraulic Station

steel shell type of furnace usually adopts hydraulic station to tilt. Stable casting point, hydraulic tilting furnace device can well control casting angle, speed.

We purchase from domestic famous brand manufacturer with consistent quality. 


Comparison between Two Types

In IF industry, in general, the melting furnace structure is divided into steel-shell with the magnetic, hydraulic furnace and aluminum-shell with reducer dump furnace. 


  • With a long life (generally normal service life of more than 10 years).
  • Stability is excellent, because the use of magnetic conductor, the magnetic conductor has two functions: first, magnetic conductor with the top wire and induction coil firmly fixed, so that coil and magnetic conductor form a stable structure. Second, the magnet can create a magnetic barrier around the coil;
  • Energy saving. Because of the magnetic guide furnace than aluminum shell furnace 3%-5% energy saving;
  • Stable casting point.  hydraulic tilting furnace device can well control casting angle, speed;
  • Good safety performance. Due to the characteristics of a leakage alarm device and refractory mud layer), its good characteristics in the tonnage is greater than 2T are chosen steel shell structure.


Aluminum Shell furnace is a simple structure form, and the service life is generally in 5-8 years, there is no magnet, lining top out mechanism, refractory clay layer, general use and 3T below the capacity. For example, a 5tons medium frequency furnace, full furnace molten iron, the overall weight of equipment up to 8-10T, if the choice of aluminum shell structure, when the reducer rotary furnace body to 95 degrees, the whole furnace will lean forward, the safety performance is very poor. Aluminum Shell furnace is suitable for short-time users, small tonnage.


1) Strong and durable, beautiful and generous, especially large capacity furnace body, need a strong rigid structure, from the angle of safety, try to use steel shell furnace.

2) the magnetic yoke made of the silicon steel sheet can shield and emit the magnetic force line of the induction coil, reduce the magnetic leakage, improve the heat efficiency and increase the output, and save about 5%-8% energy.

3) the existence of furnace cover can reduce heat loss and improve the safety of equipment.

4) Long service life, aluminum in high-temperature oxidation more serious, resulting in metal toughness fatigue. In the foundry industry site, often see the use of about a year of aluminum shell furnace shell broken, and steel shell furnace, because of less magnetic leakage, equipment life greatly beyond the aluminum shell furnace.

5) the safety of the steel-shell furnace is much better than that of the aluminum-shell furnace. The aluminum-shell furnace is easy to deform because of the high temperature and heavy pressure.

Auxiliary Equipment

Closed Type Cooling Tower

closed tpe water cooling tower

Pouring Ladle

pouring ladle


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