Vacuum Induction Melting Furnace

High Temperature Vacuum Induction Melting Furnace, Medium Frequency Up to 1700℃

This vacuum induction melting furnace adopts the theory of medium frequency induction heating and builds a high vacuum system so that the metal could be melted under a high vacuum situation. This furnace is widely used in many kinds of research and production, such as nickel and special steel, precision alloy, activity metal, high temperature alloy, magnet material, etc. Also suitable for the vacuum precision cast of small parts.

  • Adopt IGBT medium frequency power supply, the max temperature is 1700℃.
  • The vacuum system is composed of a mechanical pump, roots pump, diffusion pump, the max vacuum level is 6×10^(-3)Pa.
  • The alloy feeder built inside. The material can be fed into the melting crucible by operating the feeder handle.
  • The furnace cover is equipped with an observation window, easy to observe the performance of the furnace.
  • An induction heater consists of a rectangular copper tube, through the two mating nuts fixed on the electrode, easy to disassemble.
  • The crucible could be placed inside the inductor. The crucible material should be following the melt alloy type.

 

Vacuum Induction Melting Furnace on customer’s site:

 

Technical Specifications of Vacuum Induction Melting Furnace:

Technical Specifications 
Crucible effective volume4L
Crucible effective capacity (Steel)20kgs
Max temperature1800 ℃
Max melting vacuum●  7×10-3Pa
●  Vacuum time: open diffusion pump when preheating is complete, then up to 7×10-3Pa in 30 minutes.
Rated power60KW
Rated voltage375V
Power frequency50HZ
Rated frequency1500~2500HZ
Heat elementInduction copper coil
Vacuum system●  70L/s Double stage Rotary vane mechanical pump
●  Dia.300mm diffusion pump, Max. pumping speed: 5000L/s
●  Dia.300mm diffusion pump clod trap, effective cooling cycle for pump oil
●  Dia.300mm diffusion pump flapper valve + Dia.80mm former pump flapper valve
●  Stainless pipe + stainless bellows
Furnace Structure
Vacuum furnace shell●  Furnace Shell is a vertical cylinder with double layer water-cooling, 304 stainless steel inner was mirror polished; the outer rolled by carbon steel.

●  Double layer water-cooling arched furnace cover. Equipped with two tension springs, used to balance the weight. You can open the cover easily. When it’s locking, two tension springs can also provide furnace cover airtight pressure to ensure good sealing.

Electrode

●  The electrode is located in the left side of the furnace shell. It can work as a power supply for induction heating electrodes, and as a fulcrum of induction heater and Crucible.

●  Electrodes mounted on Sealed bearing, when needed tilting crucible, worker can operate the handle to pour the liquid steel.

Alloy feeder●  Alloy feeder is located in the center of the cover. Inside the feeder is divided into six cubicles (material of one cubicle is placed in the tipping bucket), the material can be fed into the crucible in the vacuum or protective gas.

●  When turning the feeder hand wheel every 60 degrees, there is one cubicle material fall into the tipping bucket inside the furnace cover.

●  Feeding tipping bucket is equipped with damping plate to prevent materials falls too quickly. When in use, gently shake the joystick (outside the furnace cover), you can control the speed and quantity of the material fall into the crucible

Observation window

●  The furnace cover is equipped with an observation window, easy to observe the performance of the furnace.

●  Active shutter is installed on the observation window, preventing glass from burning broken and getting dirty by steam accumulation of metal.

●  Shutter moves away shortly only when observing, controlled by the handle outside the furnace cover.

Induction heater

●  Induction heater consists of a rectangular copper tube, through the two mating nut fixed on the electrode, easy to disassemble.

●  Pre-sintering moulding crucible can be placed inside.
You can also make the crucible according to the inductor inner wall. The material of crucible is up to the melting metal.

●  In front of the sensor, at the bottom of the furnace shell (where place the ingot mould), there is a circular pipe. On the pipe, there is a circular shelf to place ingot mould. Normally, ingot mould is placed on this shelf. When you need to cast the slender ingot, the ingot mould will be high, you can remove the shelf and put the ingot mould into the circular pipe, place it on the water-cooling cover. If you have some special needs, you can replace the water-cooling cover into a suitable water-cooling ingot mould room.

Temperature measuringOn right side of the furnace exhaust pipe fitted with a temperature measuring device. When you need to measure temperature, just pull up the spring latch, turn the handle, the thermocouple tip will insert in the liquid metal. Quartz protecting tube for thermocouple prepared by the user.
Medium frequency power supply and Water-cooling●  Medium frequency power supply is a 1500-2500Hz, 50KW thyristor medium frequency equipment. To compensate for low power factor, the system is equipped capacitor.
●  The medium frequency current of furnace was sent to inductor through the outside bus-tie and water-cooled medium frequency cable. Cooling water of medium frequency cable was directed by control valve on the furnace base.
Vacuum system●  Vacuum system directly connect to exhaust port on the furnace shell. The system includes oil vapor diffusion pump, two stage rotary pump, valve, pipeline, etc.
●  The vacuum system has a 0-0.1Mpa pressure gauge, to check the rough vacuum and negative pressure of protective atmosphere.
Melting process
Step 1.  Feeding●  The materials must be carefully cleaned, removed surface contamination, oil, etc. and baked to remove moisture.
●  Some complex recycling materials must be cut off and removed surface scale, non-metallic materials, etc.
●  When feeding, you need to make sure the materials at the top of crucible is looser than the bottom. Use small piece of material to fill the gap. Place more regular shape material at the top to avoid scaffold bridging during the melting. In the direction of tapping hole can amass some granular materials.
●  Feeding movements should be light to avoid crucible damage and slags in the metallic liquid.
Step 2. Vacuum pumpingFirstly, open the 2-stage rotary pump to vacuum the furnace. At the same time, open the diffusion pump power supply, start heating the diffusion pump oil. When the vacuum of 2-stage rotary pump is 15Pa and diffusion pump have been heated for about 50 minutes, now you can close 2-stage rotary pump valve, open diffusion pump valve, vacuum the furnace to the required high vacuum.
Step 3. Melting●  Firstly, open the thyristor medium frequency power supply, increase working voltage sensors gradually. Normally, start with the small power to avoid sudden sharp rise in temperature and vacuum dropped significantly. So the general rate of power increase should not make the vacuum dropped significantly.

●  The max power of furnace is subject to the medium frequency voltage and max current.

Step 4. Refining●  After all materials melting, when need to add alloy, you can turn the handwheel, then the alloy will drop into the feeding tipping bucket. Gently turn the operation handle, the alloy will drop into the crucible at the speed you need.

●  It’s easy to cause sputtering when some alloy drop into the crucible. You need to pay attention to the speed of alloy’s adding. It can’t be too fast. Sometimes, you need to lower the power, make the liquid surface a bit harder, then adding the alloy to reduce sputtering.

Step 5. CastingWhen refining complete, no need to cut off the power, tilt crucible to pour metallic liquid into ingot mould. Notice, do not pour it out of the ingot mould.
Maintenance
Cooling water●  When melting, you should pay attention to cooling condition of each part. The temperature of cooling water should not over 50℃. If the water pressure is inadequate or some part over temperature, you should cut off the power, find the reason and fix it, then restart. The hardness of water should not be too high, should be clean. Cooling water pressure: 0.2Mpa, water consumption: 3000kg/h.

●  When stop using the furnace for a while, you need to use compressed air to blow out the remained water to prevent corrosion and extent service life.

Vacuum system●  Replace the oil of diffusion pump and 2-stage rotary pump regularly. Add diffusion pump oil as lubricating oil to the seal parts regularly.
●  Pay attention to the heater of diffusion pump regularly. You can check if the heating wire is broken by measuring current.
●  When vacuuming steam-containing gas, you should open the gas ballast valve on the 2 stage rotary pump, or it will contaminate the oil in 2 stage rotary pump and lower the max vacuum.
Furnace●  When stop using the furnace, you should clean the furnace inside and outside and vacuum it.

 

Standard Size:

ModelCapacityPowerModelCapacityPower
BR-VM-55kg40KWBR-VM-5050kgs150KW
BR-VM-1010kgs40KWBR-VM-100100kgs250KW
BR-VM-2020kgs60KWBR-VM-300300kgs500KW
BR-VM-2525kgs75KWBR-VM-500500kgs700KW