During production line inspection our specialist also found the following potential problems:

  • The raw materials used are highly abrasive and we recommend to use tungsten carbide inserts for guarantee mold’s lifetime of 1-2 million pressing cycles before inserts repair or change. We think that mold design used shall be changed to dismountable with the possibility of changing armor and mold’s kernels. Due to technological process is a commercial secret, we didn’t have access to the mix composition, but from the inspection it is obvious that high-silica components are used. Materials with high percentage of SiO2 (sand, basalt, granite, etc.) and some other components like crushed bricks with some content of silica and alumina are extremely highly abrasive and normal tool steel cannot a viable material for mold lining.

 

  Percentage in brick
Silica (SiO2) 55%
Alumina (Al2O3) 30%
Iron Oxide (Fe2O3) 8%
Magnesia (MgO) 5%
Lime(CaO) 1%
Organic Matter 1%

 

Picture 1. Percentage of Constituents of Clay Brick.

Based on industry experience, similar technological processes that use high-abrasive raw materials can be found in the production of refractory and sand-lime bricks. In these industries, the problem is usually addressed by using dismountable molds with replaceable linings made of tungsten carbide or tool steel. Tungsten carbide can last for several million cycles while tool steel needs to be replaced every 10-20 thousand cycles. Clients choose the most economically viable option based on the ability to achieve cheap steel lining or longer service life with tungsten, despite requiring a larger initial investment. If a local EDM shop is available, tungsten carbide inserts can be cut to size and the mold geometry can be remade with a small steel sheet for compensation, making them ideal in some situations. In summary, high-abrasive raw materials can be dealt with, but it requires adjustments to the technological process, mold design, and maintenance.