Vacuum melting furnace

Introduction to vacuum induction melting furnace

Application area

Mainly used for the production of nickel-based high-temperature alloys, titanium alloys, stainless steel, ultra-high-strength steel and other special alloy materials.

It is used for scientific research and production departments to smelt and cast nickel-based special steel, precision alloys, iron-neodymium-manganese, active metals, high-temperature alloys, hydrogen storage materials, magnetic materials, powder metallurgy, etc. under vacuum or protective gas.during the vacuum melting process，It can realize continuous feeding, automatic sampling and other processes.

Working principle

Under vacuum conditions, the induction coil obtains induced current through the principle of electromagnetic induction to achieve the purpose of heating. The current passes through the electromagnetic coil surrounding the metal material at a certain frequency. The changing current generates an induced magnetic field, which causes an induced current inside the metal and generates a large amount of heat to heat the material. When the heat is relatively low, it can be used in processes such as vacuum induction heat treatment. When the heat is high, the heat generated is enough to melt metal and be used to prepare metal or alloy materials.

Heating element: copper induction coil

Maximum temperature: 1800 degrees

limiting vacuum degree: 7x10-3Pa

temperature rising rate: After vacuuming is completed, start heating. Generally, the metal reaches a molten state within 30 minutes.

Smelting process: Adding materials ---> Vacuuming ---> Electrify for melting ---> Refining ---> Casting

Equipment advantages and features

1.Step-up temperature quickly

2.Adopt  high-efficiency power supply,with low heat loss and high heating efficiency;

3.products have low oxidation and with high purity qualities.

4.Can accurately control the content of each ingredient in the product;

5.operation is simple and convenient.

The components of vacuum induction melting furnace

It is mainly composed of furnace shell, inductor, crucible, tilting furnace mechanism, ingot mold mechanism, power supply device, water cooling system, vacuum system, control system, etc. The furnace body has two structures: vertical and horizontal. The furnace shell can be equipped with observation windows, temperature measurement, feeding, sampling, tamping and other devices.

1、Furnace body

There is an alloy feeder inside. By turning the handwheel of the feeder, the purpose of sequentially adding materials to the molten metal in the crucible can be achieved.

The furnace cover is equipped with an observation window to facilitate observation of the working conditions in the furnace. The glass observation window is usually covered with a shield to avoid contamination by metal vapor deposits.

You can place a pre-sintered crucible inside the inductor, or use ramming refractory material to pound the crucible firmly onto the inner wall of the inductor.  What kind of refractory materials will be used to make the crucible is according to what types of metal being smelted

Made of high-quality high-temperature resistant materials, it has the characteristics of high strength, high temperature resistance, corrosion resistance, etc., and can withstand high temperature and high pressure.

Made of high-strength carbon steel, after pickling, phosphating and rust removal, it is electrostatically sprayed, making it beautiful and elegant.Double-layer air-cooled furnace shell with 2-4 built-in cooling fans to ensure that the surface temperature of the furnace shell is below 60°C.

2、induction heating system

Including power supply, induction coil, cooling system and other equipment, it can achieve precise temperature control and uniform heating.

The inductor is located inside the furnace body. The inductor is wound by a rectangular copper tube, and the sensor is fixed on the electrode by two connectors, so it is easy to assemble and disassemble.

3、Vacuum system

Mechanical pump + Roots pump + diffusion pump vacuum unit, the working vacuum degree can reach 6×10^(-3) Pa.

Control System:

Including power supply system, PLC control system and other equipment, it can realize automated experiments and remote control.

4、security system

Including smoke detectors, alarms and other equipment to ensure experimental safety.

Vacuum melting furnace operation steps

Step one: charge feed

1. Vacuum melted materials must undergo special cleaning treatment to remove surface contamination, grease, etc., and bake to remove moisture. Overly complex casting recycling materials should be cut off, and surface oxide scale and non-metallic objects should be removed. etc.

2.The principle of feeding is to tighten at the bottom and loose at the top. Place longer rods and intricately shaped materials on the bottom and fill in gaps with smaller pieces of material. Place a relatively regularly shaped material on top of the crucible to avoid "bridging" during the melting process. Some granular materials will accumulate in the direction of the discharge port.

3.The charging action should be gentle to avoid damaging the crucible and causing slag inclusion in the molten metal.

Step 2: Vacuum

First, turn on the two-stage rotary vane mechanical pump to evacuate the furnace body. At the same time, power is supplied to the diffusion pump and the diffusion pump oil begins to be heated. When the mechanical pump evacuates to 15Pa, and the diffusion pump has been heated for about 50 minutes, the mechanical pump valve can be closed, the diffusion pump valve can be opened, and the furnace body can be evacuated to the required high vacuum.

Step 3: Electrify for melting

1.First start the thyristor intermediate frequency power supply and gradually increase the working voltage of the inductor. Generally, a smaller power is always sent in at the beginning. This is to avoid excessive power causing a sudden and sharp rise in the furnace temperature, resulting in a large amount of discharge in the furnace in a short period of time. The gas will cause the vacuum degree to drop significantly, so the general power increase rate is subject to not causing the vacuum degree to drop significantly.

2.The maximum value of the electric furnace power should be limited by the maximum value of the intermediate frequency voltage and current.

Step 4: Refining

1.After the charge is completely melted, when you need to add alloy material, you can turn the handwheel on the alloy feeder. The alloy material falls into the feeding tipping bucket, and the operating handle of the tipping bucket is gently turned by hand to add the alloy material into the crucible at the required speed.

2.Some alloy materials are easy to cause sputtering when added to the crucible. At this time, it is necessary to pay attention not to add the alloy too fast. Sometimes, the method of "conjunctival feeding" is even adopted, which is to reduce the power to slightly freeze the liquid level, and then add the alloy material. , to reduce sputtering.

Step 5: Casting

At the end of refining, the crucible can be tilted to pour the molten metal into the ingot mold without cutting off the power. Be careful not to pour molten metal outside the ingot mold.

standard configuration for complete sets of equipment

1.Furnace body  1 set;

2.control power cabinet 1set

3.induction inductor (including graphite crucible) 1 set

4.Vacuum system  1 set;

Optional spare parts

1.Induction inductor (including graphite crucible)

2.Silicone sealing ring

3.Vacuum pump oil