How do I know what alloy to use?
The brazing alloy, or what is commonly called filler metal, must be metallurgically compatible with the metal you are brazing, commonly called the base metal. Also, when brazing two dissimilar metals, it is a wise choice to use a filler metal with nickel to prevent interface corrosion.
You should pick an alloy with the lowest melting temperature in order to prevent heat distortion of your part, however most lower temperature melting alloys contain cadmium, which is hazardous. There are various silver bearing alloys, with and without cadmium, used as filler metals along with nickel and copper based alloys which are used in brazing. When furnace brazing using a controlled atmosphere or vacuum, it is important to use an alloy with no low-melting metals such as cadmium or zinc. All alloys are used for specific applications, and our Technical Dept. can help you with the right choice.
How do I know what flux to use?
The main purpose of flux is to keep the base metal from oxidizing during brazing, thereby promoting capillary action for the filler metal. The flux must be fluid when the alloy begins to melt and continue to remain fluid until the brazing process is completed. Different brazing alloys have different melt and flow temperatures, therefore different fluxes are required. Temperature and brazing time must be considered in choosing flux. Also, black, boron-modified fluxes are most commonly used in carbide brazing and areas where excessive oxides form during the brazing process. We can recommend a wide variety of fluxes for all temperature ranges and applications.
How much flux should I put on the joint?
Enough flux should be applied to the joint so it will not burn off during brazing. Application of too much flux will cause pinholes and not allow the alloy to flow properly.
How should the joint fit together?
In silver brazing, a tolerance of .001 to .004 is recommended. For copper brazing a tight, force-fit is best.
Why am I not getting a good braze?
- Unclean parts
- Improper joint fit
- Improper choice of brazing filler metal
- Improper choice of brazing flux
- Improper heat method (too hot or not hot enough)
How are silver alloys priced?
All precious metals are priced to the market of the day. You can check the charts below to track silver and copper prices. Your order will be billed on the market the day of shipment.