The core advantages of vacuum heat treatment furnace application

Vacuum heat treatment furnaces have gradually replaced traditional open flame processes with their disruptive advantages and have become the “gold standard” for high-end bearing manufacturing. What are the core differences between vacuum furnaces and ordinary fire-fired boilers? How does vacuum furnace technology have “hard-core competitiveness”?

Ⅰ Comparison of process principles of vacuum heat treatment furnaces
1. Environmental control: “pure space” to isolate oxidation
Ordinary fire-fired boilers are heated in an open flame or salt bath environment. The surface of the workpiece is easy to react with oxygen to form oxide scale (the thickness of the decarburization layer can reach 0.1-0.3mm), resulting in a decrease in hardness and an increase in the risk of fatigue cracks.
The vacuum furnace is completely isolated from oxygen by pumping to a high vacuum environment below 0.133Pa, making the surface of the bearing steel as smooth as a mirror and the metallographic structure more uniform (such as 40Cr has no decarburization layer after vacuum quenching, and the carbide distribution is denser).
2. Heat conduction method: from “extensive convection” to “precision radiation”
Traditional boilers rely on heat convection of air or salt bath media, which is prone to soft spots or deformation due to uneven temperature (such as the ovality deviation of the ring exceeds 0.05mm).
The vacuum furnace adopts pure radiation heating, combined with multi-zone temperature control technology, the temperature difference in the furnace can be controlled within ±5℃, and the deformation after quenching is reduced by 70% compared with salt bath treatment.
3. Material performance: from “passive compromise” to “active optimization”
Ordinary processes require a processing allowance (about 0.5mm) due to oxidation, resulting in reduced material utilization.
The vacuum furnace can directly process the finished parts in a non-oxidizing environment, and at the same time improve the toughness of the steel through degassing (such as reducing the hydrogen content to below 1ppm), so that the impact resistance of the bearing is increased by 30%.

Ⅱ Core advantages of vacuum heat treatment furnace
1. Zero defect surface: opening the era of “nano-level precision”
The surface roughness of the needle roller treated by the vacuum furnace can reach Ra≤0.2μm (traditional process Ra≥0.8μm), and the contact fatigue life is extended by 3-5 times with the non-carburization characteristics.
2. Microstructure: from “martensite coarsening” to “ultra-fine grains”
Through vacuum high-pressure gas quenching technology, a faster critical cooling rate is achieved to obtain fine needle-shaped martensite (grain size of more than 10 levels), which has a 40% increase in wear resistance compared to traditional oil-quenched lath martensite.
3. Win-win situation of environmental protection and efficiency: energy consumption of a single furnace is reduced by 30%
The vacuum furnace adopts a modular heat insulation design (such as multi-layer molybdenum screen + ceramic fiber composite structure), with a thermal efficiency of more than 91%, and no oil fume emissions. Calculated based on an annual output of one million sets of bearings, the cost of waste slag treatment can be reduced by more than 500,000 yuan per year.
4. Intelligent control: Error rate changes from “empirical judgment” to “digital closed loop”
Integrated PLC and infrared temperature measurement system (accuracy ±1.5℃) to achieve automatic programming of the entire process of quenching-tempering-stabilization.

Ⅲ Vacuum furnace to handle extreme working conditions of high-end bearings
1. High-temperature bearings: 9Cr18Mo stainless steel is used for vacuum carburizing, and the surface carbon concentration gradient can be controlled at 0.8-1.2%. The service life exceeds 8000 hours under 250℃ working conditions.
2. High-speed spindle bearings: GCr15 steel is vacuum nitrided to form a 5-10μm compound layer on the surface, and the friction coefficient is reduced to 0.08, meeting the 20000rpm speed requirement of CNC machine tools.
3. Complex structure For thin-walled needle roller rings (wall thickness ≤1mm), vacuum low-pressure carburizing + graded quenching process controls the deformation within 0.02mm, and the scrap rate is reduced from 15% to 2%.

Vacuum Heat Treatment Furnace