How to choose the heating chamber of the vacuum furnace and use the vacuum degree

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The types of vacuum furnace heating chambers are:

Graphite reflective screen: Generally, there are two kinds of graphite materials, hard felt and soft felt used in vacuum furnace, which are suitable for quenching, tempering and annealing of general steel. High temperature brazing, powder metallurgy and sintering, etc.

Metal heat shield: Stainless steel and molybdenum are generally used in vacuum furnaces. The molybdenum reflective screen is suitable for quenching, annealing, high temperature brazing, sintering, etc. of materials with high temperature and high requirements for the furnace environment (such as: high temperature alloys, titanium alloys, magnetic materials, etc.).

The stainless steel reflective screen is suitable for some low-temperature furnace options such as tempering, low-temperature annealing, aging, and vacuum aluminum brazing.

The choice of vacuum

For quenching heat treatment, medium vacuum (generally limit 4X10-1P a) can be used for vacuum heat treatment using two-stage pumps (fore-stage pump and Roots pump) such as bearing steel, die steel, structural steel, etc.
For some products that require high vacuum, such as (vacuum heat treatment or high temperature brazing of high-temperature alloys, titanium alloys, magnetic materials, etc.. Three-stage pumps (fore-stage pumps, roots pumps, diffusion pumps, etc.) are generally required. The limit is below 10-4Pa.

SIMUWU vacuum heat treatment furnace is equipped with China’s best vacuum pump brand EVP roots pump and slide valve pump, and can provide overseas after-sales service.

Basic knowledge:

When processing titanium alloys in a vacuum furnace, it is not advisable to use nitrogen as a cooling gas, because titanium and nitrogen react at high temperatures to form golden-yellow titanium nitride.

The movable connection parts of the vacuum furnace are all sealed and connected by O-shaped rubber rings, and this part is cooled by water.
When the workpiece is quenched in a vacuum state, vacuum quenching oil should be used, which has a lower saturated vapor pressure.

The vacuum furnace should be maintained in a vacuum or pure nitrogen state to avoid inhalation and moisture absorption when not in use.

During the heating process, the workpiece and the materials in the furnace will outgas, which will reduce the vacuum degree. SIMUWU engineers suggested that the vacuum furnace user should bake the vacuum furnace first when reusing the vacuum furnace equipment to let the water vapor in the vacuum furnace volatilize.

The heating temperature for vacuum tempering, vacuum annealing, vacuum solution treatment and vacuum aging is generally the same as the heating temperature for conventional treatment.

The vacuum tempering furnace should have a fast cooling device. The pressure of the cooling water should be greater than 0.2Mpa, and the flow rate should be adjustable. SIMUWU heat treatment service engineer reminds you to use neutral cooling water, not acidic.