Start size with 12 mm maximum length use to be suitable for a direct grinding of sample.
We interrupted the grinding process after the first minute and found a fineness of 100 % < 400 µm. After 3 minutes of grinding, the fineness has been < 250 µm. It took a total grinding time of 5 minutes to achieve the desired fineness of < 150 µm.
Because sample does not started to stick to the grinding set, even longer grinding times are possible to improve the grinding result.
By using a grinding set made of hardmetal tungsten carbide, equal grinding results will be achieved a little faster.