Vacuum Brazing of Stainless-Steel Rods into Oxygen-Free Copper Sleeves

Using a Normantherm vacuum furnace, this assembly was vacuum brazed under carefully controlled conditions to achieve a strong, uniform, and leak-tight joint.

In this brazed assembly, a 304 stainless steel rod is inserted into a precisely machined oxygen-free copper sleeve, creating a controlled overlap joint. This joint design takes advantage of capillary action during brazing and ensures good mechanical alignment between the two materials. A suitable brazing filler alloy is placed at the joint area before heating. Due to the tight and uniform joint clearance, the filler metal is able to flow evenly between the stainless steel and copper surfaces once the brazing temperature is reached.

The brazing process is carried out in a high-vacuum furnace, where oxygen and other contaminants are removed from the chamber. Under vacuum conditions, oxide formation on both stainless steel and copper is minimized, allowing the filler alloy to wet and bond effectively without the use of flux. During the heating cycle, temperature is carefully controlled to accommodate the high thermal conductivity of oxygen-free copper while maintaining the structural integrity of the stainless steel. As the filler alloy melts, it is drawn into the joint gap by capillary action, forming a continuous and uniform bond around the entire circumference.

This method produces a clean, strong, and leak-tight joint. Brazed stainless steel and oxygen-free copper assemblies manufactured in this way are commonly used in vacuum components, electrical and thermal applications, and precision industrial equipment. With an optimized vacuum brazing cycle, consistent joint quality, excellent reliability, and repeatable production results can be achieved.