PFI manufactures vacuum furnaces in carbon steel and stainless steel.
A vacuum furnace is a type of furnace or chamber that can heat materials, typically metals or metal injection molded (MIM) parts, to very high temperatures and carry out processes such as brazing, sintering and heat treatment with high consistency and low contamination.
In a vacuum furnace, a vacuum surrounds the items in the furnace. The absence of air or other gases prevents heat transfer with the product through convection and removes a source of contamination. Some of the benefits of a vacuum furnace are:
- Uniform temperatures in the range of 2000–2800°F (1100–1500°C).
- Temperature can be controlled within a small area.
- Low contamination of the product by carbon, oxygen and other gases.
- Quick cooling – quenching – of the product.
- The process can be computer controlled to ensure metallurgical repeatability.
Heating metals to high temperatures normally causes rapid oxidation, which is undesirable. A vacuum furnace removes the oxygen and prevents this from happening.
An inert gas, such as Argon, is typically used to quickly cool the treated metal back to non-metallurgical levels (below 400°F) after the desired process in the furnace. This inert gas can be pressurized to two times atmosphere or more, and then circulated through the hot zone area to pick up heat before passing through a heat exchanger to remove heat. This process continues until the desired temperature is reached.
A common use of a vacuum furnace is for the heat treatment of steel and other alloys. Many general heat-treating applications involve the hardening and tempering of a steel part to make it strong and tough through service. Hardening involves heating the steel to a pre-determined temperature, then cooling it rapidly.