VOD Furnace Operation Technology
Vacuum induction furnace (VOD furnace) is a reducing medium-frequency electric furnace for producing metals and alloys. A VOD furnace works by using a water-cooled vacuum chamber that is connected to an electrical power supply. This power supply goes through a vacuum where induction coils create a magnetic field which heats the workpiece. Everything within the furnace is heated by the electric current, which can reach temperatures over 2500 degrees Celsius.
VOD furnaces are used for melting, alloying and refining a variety of metals such as steel, stainless steel and aluminium. They are used heavily in large industrial applications due to their efficient process times, which helps to save time and money.
Step 1: Pre-Turbo Pump
The pre-turbo pump is the starting point for accessing the vacuum in the chamber. It should be connected to the vacuum chamber and the power, which is often three phase or single phase with a start and stop switch. To get the chamber to a full vacuum, the pump needs to be connected and powered up and then allowed to pump out the air over a period of 20 to 30 minutes.
Step 2: Heating Up
Once the inside of the VOD furnace is at a vacuum state, it is ready to be heated up. This is done by adjusting the capacitors, which are external and connected to the three phase or single phase power. To start the heating process, the vacuum chamber needs to be filled with the correct charge of electrodes. The electrodes provide the magnetic energy which is then converted into a high temperature hot plasma, this is what heats up the chamber and everything inside.
Step 3: Heating Elements
To ensure the chamber and all its contents are heated up evenly, heaters are used. This can be a combination of ceramic heating rods, quartz tubes, and ceramic-coated silicon carbide heating elements. These heaters should be arranged across the top and bottom to ensure that the entire chamber is heated up. If a stainless steel burnout chamber is being used, then a combination of both ceramic heating elements and quartz tubes can be used.
Step 4: Melting Process
Once the chamber is heated, the materials can be melted. The electrode molten material will be either poured or injected into the chamber. This process usually takes 15 to 25 minutes and the molten material is then poured into a container or cast in a mould. If a graphite crucible is being used, then the material can be melted directly inside the crucible.
Step 5: Refining and Alloying
If alloying or refining is required, different selected materials can be put into the crucible. Stainless steel is often melted inside a graphite crucible to reduce the amount of oxidation. The crucible is then heated up to the desired temperatures and allowed to stay at that temperature for a certain period of time. This is important as it allows for the complete alloying or mixing between the metals. After the desired time has elapsed, the material can then be poured from the crucible.
Step 6: Cool Down
Once the process is complete, the chamber will need to be cooled down. This is done by either using a cooling fan or by the natural cooling from the furnace body. During this process, it is important to have the fan run for a set time after the chamber has cooled down. This helps to ensure that the chamber is in its proper alignment and is structurally sound.
Conclusion
VOD furnace operation technology is a common process in the production of metals and alloys. Understanding the steps of the process helps to ensure that the product or material is produced safely, cost-effectively and quickly. Familiarity with the technology should be taken into account when making a decision on the type of furnace or the desired temperature range needed. By integrating these factors, a successful VOD furnace operation technology process is sure to be achieved.
