A vacuum sintering furnace is a protective furnace that heats items in a vacuum environment. Heating methods include resistance heating, induction heating, and microwave heating.
Vacuum Induction Furnace:
This furnace uses induction heating to protect the workpiece. It can be classified by frequency: low, medium, or high, and is considered a subcategory of vacuum sintering furnaces.
Vacuum induction sintering furnaces use vacuum or protective atmospheres with medium-frequency induction heating to sinter hard alloy tools and various metal powder compacts. They are widely used in industrial production of hard alloys, metallic dysprosium, and ceramic materials.
Principle and Application:
The vacuum induction tungsten sintering furnace operates under hydrogen protection after vacuum pumping. Tungsten crucibles in the coil are heated by medium-frequency induction, generating high temperatures that transfer heat via radiation. It is suitable for powder forming of refractory metals like tungsten, molybdenum, and their alloys in research and military applications.
Main Structure and Components:
Typically vertically arranged, the furnace consists of:
- Furnace body
- Vacuum system
- Water cooling system
- Pneumatic system
- Hydraulic system
- Loading/unloading mechanisms
- Base and worktable
- Induction heating system (tungsten heater with advanced insulation)
- Power supply
- Medium-frequency power supply
- Electrical control system
Main Functions:
Hydrogen is introduced after vacuuming to control pressure and atmosphere during sintering. Fiber-optic infrared thermometers and armored thermocouples continuously measure temperature (0–2500°C). Temperature feedback is automatically sent to the medium-frequency power supply via intelligent controllers, enabling automatic control of heating and insulation programs.
Vacuum Sintering Furnace Safety Operating Procedures:
- Ensure the medium-frequency power supply, vacuum furnace body, and cooling water reservoir are filled with clean water.
- Turn on the water pump for normal circulation and adjust water pressure to specified values.
- Check vacuum pump power, belt tension, and oil level. Manually rotate the belt pulley to ensure proper operation before starting the pump.
- Inspect the vacuum furnace interior: cleanliness, coil insulation, and vacuum seal condition.
- Verify that the vacuum furnace handles operate smoothly.
- Check the rotary Maxwell vacuum gauge.
- Ensure graphite crucibles and accessories are complete.
- Power on the furnace and medium-frequency system. Test the variable frequency start procedure before operation.
- Clean observation and temperature measurement ports before each inspection.
- Load materials according to specific sintering requirements. Do not arbitrarily change packaging rules.
- Add two layers of carbon fiber in the heating crucible and cover with insulation boards to maintain temperature and prevent thermal radiation.
- Place the vacuum sealing strip.
- Rotate and lock the furnace top cover to the body with the handle.
- Slowly open the butterfly valve to achieve the required vacuum.
- Start the variable frequency system, adjust medium-frequency power, and operate according to the material-specific sintering procedure under the required vacuum conditions.