Epoxy polyester

During dry grinding, sample is sticking very fast. Lot of particles remains > 120µm; a longer dry grinding is not recommended.

Also a grinding in lightweight agate bowl and balls is not suitable for grinding your kind of sample.

Even with reduced speed (only 360rpm) sample starts sticking before the desired fineness will be reached.

After the second minute, sample is sticking stronger to bowl and balls. Still particles > 120µm can be found.

A planetary ball mill is not suitable for grinding this kind of sample.

Usually, by grinding samples with a rotor speed mill, majority (50% vol.; d50) of resulting particles use to be smaller as half sieve opening diameter. With 120µm sieve ring, 50% (vol.) of particles should be < 60µm.

After 2 minutes, all sample has been ground successfully. Rotor and sieve ring became quite hot. We are guessing that a grinding of higher amounts will lead to a melting of particles in front of the sieve ring.

If higher amounts should be ground, accessories for grinding large quantities will improve the airflow and will chill sample somehow better. Probably an embrittlement with liquid nitrogen will be helpful.

Using of the optional active sample exhauster system with cyclone separator will chill rotor, sieve ring and sample much better.