Vacuum Furnace Articles

Vacuum Furnace for Effective Vacuum Brazing

The materials that are too complexed to be machined are joined using various methods. There are many metal joining processes, each having advantages for certain applications.

Vacuum brazing is an important process which involves three process and utilizes vacuum furnace to create a bond that is leak tight, non-corrosive, and stronger than alternative joining methods.

The first step of vacuum brazing is very easy as due to tight tolerances, many components fit tightly together and are ready brazing filler material to be applied to the joining area. In the second step the braze alloy is applied to the joining area. The final step, vacuum furnace treatment which involves heat up, preheat, holding period, braze alloy solidification, and quenching.

It should be kept in mind that Vacuum brazing doesn't just join metal components, but also enhances the quality and value of the resulting assembles in other ways.

Nickel braze alloys are used as fillers to fill the gap between the parts being joined in vacuum brazing. Nickel alloy fillers have extensive applications, including all commonly used stainless steels, tool steels, low carbon steel etc.

The brazing process has the ability to clean and brighten the metals. This is immediately evident when parts come out of the furnace.

During the vacuum braze process, oxides, oils, and other contaminants from the part assembly gets removed more effectively than chemical cleaning. This process also increases the productivity because no flux or other contaminants need to be removed after the vacuum braze process.

Vacuum brazing can provide several simultaneous thermal treatments with some stainless steels and/or precipitation hardened alloys.

Single assemblies, or large quantities of assemblies, can be efficiently brazed in a vacuum furnace. This enables a commercial vacuum braze operation to process a small assembly with other jobs needing the same brazing cycle. The capacity of the furnace limits the size of the vacuum brazed piece. The typical brazed part is small enough to run hundreds of brazed assemblies. However a heat treater with various sized furnaces can schedule efficient runs of thumbnail sized or large single piece assemblies.

Before resorting to vacuum brazing lot of experimentation and prototype work is needed. For selecting correct brazing alloy one should have clear understanding of the assembly application as well as metallurgical expertise. Vacuum brazing utilizes capillary action to draw braze alloy into the interface between parts.

Many nickel braze alloys contains elements like boron, phosphorus, silicon, etc and are normally used to bond stainless steels. If the joint gap is wide it will result in centerline band which is brittle. However these bands and hence the brittleness can be minimized, by controlling over variables like time, temperature, and braze joint clearance. Most instrument and part assemblies need a leak-tight joint that vacuum brazing provides. To ensure that bonding area is not a weak link proper procedures should be followed.