Vacuum brazing is a particular type of furnace brazing, where vacuum is created in the furnace for carrying out brazing process. Unlike other heat treating furnaces which uses protective gas atmosphere, vacuum furnace make use of comparatively low atmospheric pressures.
This metal joining technique provides much clean, superior, and flux-free brazed joints along with high strength and integrity.
Vacuum brazing is actually a three step process, which finally creates a bond that is leak tight, non-corrosive, and stronger than alternative bonding methods.
The parts to be joined are positioned together. If the components to be joined are complex, then they are assembled with special tack welding, fixturing, staking, or a combination of all these methods.
Most of the braze joint areas lend themselves to a gel binder and braze alloy sheet or powder. Some other form of alloys, such as wire, preforms, or foil can be manually applied to the braze area.
- Simultaneous vacuum brazing of multiple joints
- Uniform heating and cooling for consistent metallurgy
- No heat affected zone (HAZ)
- Reliable and repeatable
- Furnace batch process for one or a thousand assemblies
- Fluxless brazing – no post braze cleaning
- Simple or complex assemblies with varied component types
- Clean, bright assemblies
- Leak tight, high strength joint area
Stainless steel, Titanium, Stellite, Molybdenum, Carbon steel, Carbide, Copper and Ceramic.
Filler Materials or braze mediums include:
- The size and shape of items that can be vacuum brazed depends on the type of equipment operated by the heat treater. For large items, check the availability of suitably-sized facilities at an early stage.
- The process best suits joints in parallel planes that can be brazed horizontally. These usually are flat panel-type structures
Complex shapes and designs need to be carefully thought out to allow braze mediums to flow in the capillary action, complex designs and incorrect braze mediums and preparations can cause the braze to be unsuccessful.
It can be noted that Vacuum Brazing is a very successful method of joining dissimilar materials or complex components compared with alternate methods when correct designs and jigging have been established with repeatable computer controlled processes.
All of the following information should be included if possible. If uncertain, ask your heat treater before producing a specification:
- Material: type, grade, and the standard from which it is drawn, with drawing, composition and mill certificate where available.
- Braze medium or filler material
- Any general standards applicable (national, international or company) that contain relevant details which must be adhered to.
- Existing condition; e.g. details of any prior heat treatment, such as hardening and tempering, solution treatment and ageing, intended to establish mechanical or other properties.
- The level of mechanical properties required.
- The type(s) of testing required; e.g. hardness (Vickers, Brinell), tensile etc. and any special locations for testing or the removal of samples for test pieces.
- Requirements for any special certificates or data to be provided by your heat treater.
Guidance and information is always available from our experience heat treatment professionals.
Our procedures and work instructions are fully documented under our AS 9100 and ISO 9001 quality management systems.