How to Select Vacuum Heat Treatment Furnace

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Vacuum heat treatment furnace can be divided into vacuum quenching furnace, vacuum tempering furnace, vacuum annealing furnace and so on.

Vacuum quenching furnace: vacuum quenching furnace can be divided into vacuum oil quenching furnace and vacuum gas quenching furnace.

1) Vacuum oil quenching furnace is suitable for vacuum heat treatment of die steel, spring steel, stainless steel, bearing steel, superalloy steel, etc. Its main characteristics are wide data scale, strong hardenability, low cost and reusable quenching oil. The shortcomings are: the deformation is relatively large, and the follow-up requirements of the workpiece are clean. The vacuum oil quenching furnace can be divided into two-chamber furnace and three-chamber furnace.

2) Vacuum high-pressure gas quenching furnace is suitable for vacuum heat treatment of high-speed steel, stainless steel, die steel and other materials with good hardenability. It is characterized by small deformation of parts and no need for cleaning after heat treatment. The shortcomings are that quenching gas can not be recovered and the cost is high. Vacuum high pressure gas quenching furnace can be divided into horizontal type and vertical type. Horizontal type can be divided into single room, double room and three rooms. Vertical type is suitable for heat treatment of ring-shaped, cylindrical and long rod-shaped parts. The quenching pressure of vacuum high pressure gas quenching furnace is usually 2bar~10bar. According to the user’s needs, parts can be selected for pressure furnace type.

2. Vacuum tempering furnace: Vacuum tempering furnace can be divided into single chamber, double chamber and vertical type. Usually, nickel-chromium strip is used to heat the highest temperature at 800℃. Vacuum tempering furnace is usually suitable for parts with bright appearance and no oxidation color after tempering.

3. Vacuum annealing furnace: Vacuum annealing furnace can be divided into single chamber, double chamber and vertical type. Vacuum annealing furnace can select medium and high temperature and low temperature according to the part data, (medium and high temperature 800℃～1350℃, low temperature 800℃).

Selection of Heating Chamber for Vacuum Furnace
1. Graphite reflecting screen: Hard felt and soft felt are usually used in vacuum furnace. They are suitable for quenching, tempering and annealing of common steel. High temperature brazing, powder metallurgy and sintering.

2. Metal heat shield: stainless steel and molybdenum are commonly used in vacuum furnaces. Molybdenum reflective screen is suitable for quenching, annealing, brazing and sintering of high temperature materials (such as superalloys, titanium alloys, magnetic materials, etc.) which have high demand for furnace environment. Stainless steel rice shooting screen is suitable for tempering, low temperature annealing, aging, vacuum aluminium brazing, and some low temperature furnace type selection.

Selection of Vacuum Degree
1. Vacuum heat treatment of bearing steel, die steel and layout steel can be selected for quenching heat treatment by using medium vacuum (usually limit 4X10-1Pa) and two-stage pumps (front pump and Roots pump).

2. Vacuum heat treatment or brazing at high temperature for some commodities requiring high vacuum, such as superalloys, titanium alloys, magnetic materials, etc. Three-stage pump (front pump) can be selected. Roots pumps, decentralized pumps, etc.) usually require a vacuum limit of 10-4Pa.

Selection of Control System
1. Standardize the equipment: take imported temperature controller and programmable controller as the center, complete temperature programmable, manual and active control.

2. Accounting computer control system: with industrial computer and programmable controller as the center technology programming, storage and report forms. It can operate independently, actively, manually and technically.

3. Cluster control system of accounting computers: high-tech control system of monitoring, collecting data, operating status and report management of several vacuum furnaces with industrial computer as the center.