One of the most efficient methods of joining aluminum parts is aluminum dip brazing. This is a process of joining two or more pieces of 6061 Aluminum simultaneously with a third; molten filler metal.
By uniformly heating the joint area above the melting point of the molten filler metal, but below the melting point of the parent metals, the molten filler metal flows into the gap between the other parent pieces by using capillary action.
As the assembly cools, a remarkably strong metallurgical bond is achieved. The brazed joints are often stronger than the two (parent) metals being joined together.
Because the parent metals being joined are not melted. They are not distorted or out of shape, and hold on to their original metallurgical characteristics. Dip brazing may be the most versatile method of metal joining available. Configurations of the greatest complexity are thus perfectly joined in one dip brazing operation, regardless of the number of joints involved.
Dip brazed joints have an exceptionally clean, refined appearance. Aluminum dip brazing as often the ideal metal joining method for various industries.
There are numerous cost advantages in using this process. Comparatively, dip brazing yields the lowest cost given its best characteristics in strength, control, and flexibility.
Material costs are lower in dip brazing than that of assemblies using expensive castings and time-consuming machining operations. Costly special tooling is minimized; instead simple and multi-purpose fixturing is utilized. A dip brazed assembly’s finish is uniform, clean, and smooth. The even continuous joint left by the process requires little, if any, mechanical finishing.
Time savings is another cost advantage. Regardless of the number of joints involved in an assembly, joining is performed in a one dip braze operation, minimizing time and costs.
In the dip braze process, the filler metal melts and flows into all joints through capillary action. The beauty of this process is that even a simple joint will have equal or superior strength to the base metal. Temper can be restored by an aging process to T4 or with an extended heat treatment operation (artificial age) to achieve a T6 temper.
Aluminum dip brazing achieves strong leak-tight joints regardless of the number of joints and the thickness of the base materials. Through capillary action, the process seals the joint with continuous leak-tight properties. This property is required in EMI/RFI applications. The majority of the instrument and part assemblies require leak-tight joints which aluminum dip brazing provides. Visual inspections confirm if the assembly is sealed properly. In addition, we can recommend additional testing procedures for the assurance of leak-tight assemblies.
Through aluminum dip brazing, the assemblies are uniformly heated to specific brazing temperatures and allowed to cool at an even rate. This helps to eliminate distortion and permit the joining of metals of diverse thicknesses with a positive bond.
The application of the dip brazing method of joining is limited only by the imagination of the design engineer. The most complex shapes and sizes are brazed with the distortion factor at a minimum. In the salt bath, the bath medium contacts the assemblies evenly, heating it uniformly by conduction to minimize distortion. While brazing is quick, salt bath brazing proceeds four to five times quicker than atmosphere furnace brazing, resulting in less thermal distortion of the brazement (at half the cost of furnace brazing).
Brazing out performs welding also in the rate of distortion due to its uniform heat application. Other methods of joining, such as heliarc, spot, and torch welding cause extreme thermal distortion which cannot be tolerated in today’s design of precision assemblies.
Aluminum dip brazed joints form evenly and require little, if any, mechanical finishing. The process does not leave any unattractive slag at the braze joints. All dip brazed assemblies are chemically cleaned following the braze process. The assemblies are shiny and clean, thus reducing unnecessary finishing costs and time. Glass beads also can create a very uniform finish which is an option at Parfuse Corporation.
When considering which metal joining method to select for a specific assembly, some factors need to be considered: strength, the physical characteristics of the components, permanence, the nature of the joint, and the production level required.
The following Table A rates the various metal joining methods: good, better, and best. Brazing rates the best in strength, control, and flexibility. It is also better than other methods in economics and energy used.
| Table A | Economical | Strength | Energy Used | Control | Flexibility |
|---|---|---|---|---|---|
| Mechanical Bonding | Best | Good | Best | Good | Good |
| Adhesive Bonding | Good | Good | Good | Good | Good |
| Soldering | Good | Good | Good | Good | Good |
| Welding | Good | Good | Good | Best | Good |
| Aluminum Dip Brazing | Best | Best | Best | Best | Best |
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