Vacuum Brazing of Medical-Grade 304/316 Stainless Steel Tubing: Application of High-Vacuum Brazing Furnaces

2026-08-18 14:07

Vacuum brazing of medical-grade 304 and 316 stainless steel tubing is a core process in the manufacture of high-precision medical devices, such as endoscopic components, surgical instruments, medical catheter connectors, and auxiliary tools for implants. Given the medical industry’s stringent requirements for sterility, corrosion resistance, and the absence of residues, vacuum brazing stands out as the optimal choice due to its flux-free nature and ability to produce dense, high-integrity joints.

Brazing medical-grade stainless steel requires careful consideration of biocompatibility, corrosion resistance, and melting temperatures. Nickel-based filler metals (such as the BNi series) are commonly used for high-temperature vacuum brazing (950–1150°C); they offer high joint strength and excellent corrosion resistance, making them ideal for medical components subjected to high pressure or high-temperature sterilization. We recommend the use of BNi-5 filler metal.

Vacuum brazing of medical-grade 304/316 stainless steel tubing necessitates a “high-vacuum, high-temperature” environment. High vacuum effectively evacuates oxygen and reduces or prevents the formation of surface oxide films, enabling clean, flux-free welding that ensures medical-grade biocompatibility and hermetic sealing. High temperatures are required to melt nickel-based filler metals; the resulting low viscosity and capillary action allow the filler to fill micron-scale assembly clearances, while simultaneously promoting atomic diffusion between the base metal and the filler to form a high-strength metallurgical bond.

SIMUWU RHVB-557H high-temperature vacuum brazing furnace designed for flux-free joining of medical-grade stainless steel components.

SIMUWU’s RHVB-557H high-temperature vacuum brazing furnace is fully capable of meeting these requirements; its specifications are detailed below:

Furnace type	Horizontal , single chamber, internal circulation
Loading method	Front loading
Effective working zone	500×500×700 (W×H×L mm)
Max. Loading Capacity	300kg
Power supply	3Phase 380V (±5%) ; 50Hz
Max.design temperature	1350℃
Working temperature	600-1300℃
Temperature uniformity	9 point temperature measurement (±3℃) (temperature measurement standard AMS2750E)
Temperature control accuracy	S-type thermocouple ±1℃ (temperature measurement standard AMS2750E)
Quantity of heating zone	3 Independent temperature control zones
Heating element	High-temperature molybdenum
Time to reach working temperature	≤ 75min
Heating rate of empty furnace	0~20℃/min(speed adjustable and controllable)
Ultimate vacuum	6.7 x 10-4 pa (Empty furnace, cold state, after sufficient bake-out)
Working vacuum	5 x 10-3 pa
Time to pump to working vacuum	≤40min (After diffusion pump preheating, empty furnace, cold state)
Pressure rising rate	≤ 0.67 Pa/h (Empty furnace, cold state)
Cooling method	Gas cooling/natural cooling
Cooling gas	Nitrogen or argon (purity: 99.99% or 99.999%)
Cooling rate(empty furance 1200℃~150℃)	≤ 45min
Nitrogen consumption per furnace	≤ 7m3
Max. cooling gas inflation pressure	≤ 2bar
Partial pressure	50-1000 Pamanual and automatic partial pressure control
Operation model	Manual or automatic control
Equipment color	Customized