Braze Failure Analysis

Brazing:  Mechanical Principles To Solve Problems

I quite often get calls about brazing problems that people are trying to solve by repeatedly brazing the two parts together.  Since brazing is technically the joining of two materials through the use of a third, dissimilar material this approach makes sense.

If you go through the proper startup procedures and a machine doesn’t work it is very common to start taking the machine apart to see what is broken.

The same technique can be applied to braze joints. If you have two parts and you cannot braze them successfully then you might want to consider brazing each one separately in a process called tinning.

The most common example in my world is brazing a piece of carbide to a piece of steel with a layer of flat braze alloy or tri-metal in the middle. If the braze joint fails people change something, put the three parts together and try it again.

Quite often a great deal of valuable information can be derived from seeing how the braze alloy sticks to the carbide and the steel separately. Instead of a flat piece of material you take a very small bit of braze alloy as a wire, put it in a rather generous size pool of flux on either the steel or the carbide and then heat it.  It is good if it flows out over the part and bad if it balls up.

This gives you the ability to see exactly what’s going on and makes analysis of changes much easier and more reliable.

Actually this technique can be used to work on any problem. If you want to solve a problem with the machine then you take it apart and examine each component. When you find the bad component then you have solved the problem. Sometimes you have problems with a machine, you take it apart, clean and inspect everything, put it back according to specifications and the problem goes away. This is why it’s often a good idea to do regular retraining.

There’ve been many times when I have been lecturing or training and I’ll explain that you should do something and should not do something else. When I watch the audience I can often see somebody, usually in the back row, who has an expression on their face that clearly says “Uh Oh, I better quit doing that”.

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