Vacuum Furnace Industry
Vacuum furnace technology was developed for very high quality applications. A pressure vessel is pumped out with a vacuum pump to produce a pressure less than atmosphere.
In most applications, another gas is then injected back into the vessel. This gas aids in heat transfer and assists in other surface treatments such as Ion-Nitriding and Carburization.
Initially, all vacuum furnaces were electric, and electric furnaces still dominate the market.
Gas units were developed in the mid-1980's. Gas vacuum furnaces have several advantages over electric furnaces, including:
- lower operating costs,
- lower initial cost, and
- faster cycle time.
However, a key disadvantage has kept it from taking over more of the market. Gas vacuum furnaces currently only operate up to about 1,950oF (initially only to about 1,250oF). Electric furnaces can operate up to 2,400oF.
Although an estimated 90% of all applications take place at less than 1,950oF, this temperature limit has been the biggest barrier for the gas unit. Research continues in the higher temperature applications for gas. Currently, there are a very limited number of gas fired vacuum furnaces in operation.
High temperature applications that are NOT possible for current gas vacuum technology includes: Sintering (tools and parts made from powdered metal and heated to about 2,400oF to harden) and exotic alloy metals used in high temperature applications such as aircraft turbines.
Any existing atmosphere controlled batch process is a good candidate for vacuum. However, there must be a need for higher quality results to justify the higher cost of a vacuum furnace over a standard atmosphere controlled furnace.
Typical gas vacuum furnaces have inputs of 1.0 million - 1.2 million BTUs/Hour; electric furnaces are 150 - 200 kW. A batch process may run anywhere from a few hours to a couple of days, depending on the size of the load and what is being accomplished.
Clients use vacuum boosters for:
- Heat Treating
- Optica Coating