glass

As desired, hardmetal tungsten carbide has been used for bowl and balls. Also other materials like zirconium oxide or steel will be suitable for grinding your sample.

For all other materials, bowls up to 500 ml volume use to be available (hardmetal tungsten carbide – max. 250ml bowls).

After 4 minutes of grinding, sample is sticking lightly to bowl and balls. This uses to happen after the majority of particles reached a fineness of < 20-30 µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further.

A longer dry grinding time is not recommended.

To determine the fineness, we sieved the complete sample with our Vibratory Sieve Shaker ANALYSETTE 3 Pro and a test sieve of 100 µm mesh. Already 80 % is able to pass the test sieves mesh.

For a finer grinding, we recommend grinding in suspension.

Because of the high density of hardmetal tungsten carbide (~ 14,9 g/ml), also 20 mm Ø grinding balls might be suitable.

To verify, the rest of sample (200g) has been ground in this trail.

Also with 20 mm Ø grinding balls, no intact pieces can be found after the first minute of grinding.

Sample use to stick a little stronger to bowl and balls after a total of 4 minutes of dry grinding. Longer dry grinding times are not recommended.

The detected fineness use to be 87% < 100 µm. The desired task of min. 75 % < 100 µm has been achieved.