- Design components to be self-fixturing and self-locating. Aluminum's rate of expansion is approximately 1/3 greater than that of the fixturing material. As such, fixturing is generally kept simple and to a minimum.
- Some distortion will be present on brazed parts. Aluminum reaches annealed condition at brazing temperatures. Parts are quenched immediately after brazing. Some straightening can be performed to improve the distortion. In some cases, closely toleranced features must be removed from the component part and machining stock may need to be added so that these features can be machined after the brazing operation.
- Parts must be vented. Brazing salts are very dense. The density of the salt makes the aluminum very buoyant. The salt density, combined with the soft state of the aluminum, dictate a specific fixturing orientation to allow for easy immersion and removal from the bath. In some cases we may ask that vent holes be present to help this condition. The vent holes can be welded closed after the brazing operation. No closed cavity can be present due to the pressure created by expanding gases generated by the brazing flux.
- Filler metal comes in different forms.
- .003 thick shim
- paste (powder mixed with water)
- wire of varying diameters clad brazing sheet
- Joint clearance must be controlled. Dip brazing depends on the capillary action created by the proper joint clearance. The following are general guidelines only. Please consult us if you are designing your own component parts for dip brazing.
|
Joint Width |
Suggested Clearance |
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|
inches |
mm. |
inches |
mm. |
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|
<0.188 |
<4.76 |
0.002-0.004 |
0.05-0.10 |
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|
>0.187 |
>4.75 |
0.004-0.006 |
0.05-0.15 |
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|
* When clad brazing sheet is used the clad side of the sheet must be in direct contact with the mating part. |
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