How to Braze- Part 3
Welcome to our series on how to braze! We have put together a tutorial on how to braze and broken it up into 4 parts. We will be adding a new post every few days so be sure to check in and visit us often so you can take advantage of this valuable information. In parts 1 and 2 of this series we discussed saw plate and how to prepare the saw plate for brazing, and Flux and how flux affects brazing.
When brazing carbide tips you will need:
- Braze Alloy or silver solder
- Brazing Flux
- Carbide tips
- Steel saw plate
- Also, you will need a tool to heat the braze alloy
- And you will also need a tool to help guide the carbide tip onto the saw plate.
*For successful brazing the quality of the materials used is very important and can have a significant effect on reducing the amount of tip loss and breakage you experience. We proudly sell what we believe to be some of the best brazing flux, Braze alloy, and Carbide Tips in the industry.
Part 3: carbide saw tip and preventing tip loss and breakage
The Carbide Saw Tip:
It is essential that the carbide tip be tested for wettability. The simplest way to do this is to put a very tiny piece of braze alloy wire in the middle of the carbide tip with flux. Then heat the tip and see how far the braze alloy flows. If the braze alloy balls up there is something wrong with the tip. If the braze alloy flows out into a wide, flat puddle then the tip wets well. We sell Carbide tips and have a special treatment that increases wettability.
Theoretical and Actual Braze melting points
Steel saw plate heats up much faster than carbide tips. In tests it looks like it is about a ratio of 3:1 to 5:1. If you heat the steel saw plate and the carbide tip equally the steel will get much hotter, much faster than the carbide tip.
Whether you are using induction brazing or torch brazing you should apply your heat to and then through the carbide saw tip. Ideally the carbide saw tip will come up to temperature which will heat the braze alloy which will then heat the adjacent steel to a depth of no more than 0.200”. You can tell how much steel got hot by how far the braze alloy flows onto it. The outer limit of the flow should be no more than 0.200” from the carbide tip and 0.100” is better.
Tip Loss and Tip Breakage
This concerns just the carbide tip. Failure of the steel shoulder is addressed in Part 1 of our series.
Tip loss occurs when the braze alloy does not stick to the steel or to the carbide. If the laser cut saw plate is not gummed (ground) back enough the braze alloy may not adhere fully. The tip will come off. On the back of the carbide tip will be a series of horizontal lines stretching from side to side of the saw tip. These lines are marks left by the notches from the laser cutting. Laser cutting does not really cut. Instead it melts a series of connected holes. This is what creates the lines.
If the carbide tip is not treated properly for wetting and brazing the tip will come off and leave the braze alloy in the notch. Often there will be a thin gray film on top of the braze alloy in the notch. You can scratch this film with almost anything sharp and expose the yellow braze alloy underneath it. This is caused by the surface treatment on the carbide coming off. So the braze alloy stuck to the surface treatment but the surface treatment did not stick to the carbide.
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