Problems and Causes of Carbide Cutting Tools

Tungsten carbide brazed cutting tools usually have some brazing problems after brazing. Below are some of the braze problems and their causes. 

1. Tungsten carbide tip fractures and cracks

The main reasons for the fracture and the cracks in the brazing are as follows:

A: The angle of the rough surface between the bottom surface of the cutter head and the base of the cutter head is not appropriate and the brazing space is too small, so the welding material and flux cannot be entirely distributed.

B:  Mismatched solder lugs are too short relative to the braze face, resulting in direct contact between the bottom end of the carbide tip and the base metal, with the braze material distributed among them.

C: Heating and cooling times are too fast or too slow

D: The soldering temperature is too high. Since the coefficient of linear expansion of cemented carbide is very low, if the temperature is too high, large thermal stress will be generated in the joint, which exceeds the tensile strength of cemented carbide, which will lead to the cracking of cemented carbide.

2. Braze porosity

The main reasons for this brazing problem with pores are:

A: If the soldering temperature is too high, it will cause zinc foaming in the solder tab material

B: If the soldering temperature is too low, the flux will not be melted completely, resulting in foaming

3. The carbide tip falls off

The main problems with carbide tip fall off are because:

A: The choice of solder material is incorrect, it cannot be wetted with the base metal, or the wetted area is too small

B: The soldering temperature is too low, and the solder does not fully penetrate, resulting in a decrease in the strength of the braze and the cutter head falling off

C: The solder material is too small, and the strength is reduced

D: The temperature is too high, and part of the solder overflows

E: The solder material is not concentric, resulting in uneven distribution of the solder, forming part of the brazing seam false brazing, and insufficient brazing strength.

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