Extruded PVC

We started our first trial with sample 1 (25 cm long and brittle material). For such an application, our Cutting Mills can be used. With a desired fineness < 4 mm, a Universal Cutting Mill PULVERISETTE 19 or Universal Cutting Mill PULVERISETTE 19L (Large) are recommended to use.

Longer samples can be fed by the standard funnel. For safety reasons, we recommend precutting a sample < 15 cm, so a sample will not be pulled out of the user’s hand. Wearing personal safety equipment is obligate for the user.

We prepared a batch of 535 grams and broke the fragments manually in the middle. The majority of sample was already < 15 cm, the largest fragment was about 17 cm long.

The used Universal Cutting Mill PULVERISETTE 19 with an adjustable speed between 300 rpm and 3000 rpm was equipped with a standard rotor with V-cutting edges and fixed knives made of hardened stainless steel. When fiber enforced samples are fed on a regular basis, we recommend using the rotor with V-cutting edges and fixed knives made of hardmetal tungsten carbide for a much longer durability.

We used a speed setting of 1500 rpm for comminution. With higher speed, the grinding would be faster, but also more of fine sample dust might be formed. A lower speed setting would require longer grinding times and result in less of fine fraction, but too low settings might cause a blockage of the spinning rotor. Then the sample residues need to be removed before the machine can be switched on again.

We always fed two fragments together. This way, a thin fragment will not rest on the first fixed knife with the standard funnel and it is not required to use the sample pusher this often.

It took only 90 seconds until the 535 grams of sample was fed and ground. The used 3 Liter vessel was almost filled to its maximum with ground sample material. With photo 02, we shook the vessel to spread the ground particles on the surface of the vessel.

Next to plenty of ~ 4 mm wide particles, also a lot of fine fragments stuck to available surfaces by electrostatic forces. The grinding chamber was cleaned rapidly by vacuuming with a soft brush. A few traces of residues could be spotted on the rotor surface. From 535 grams of fed sample, we packed 524 grams. About 11 grams of fine, electrostatic charged sample material was vacuumed off.

Sample 2 was left intact for feeding. We ground the sample without a precutting first. The mill was adjusted to 700 rpm in order to achieve a coarser particle size distribution.

We fed 3 of the thinner pieces, but it was required to use the sample pusher much more often, compared to result one. Because of this, we aborted the trial after two minutes and used a standard gardening scissors to precut the fragments < 5 cm. The preparation took about two minutes and feeding of the rest of the fragments took only one minute.

The ground sample filled the collecting vessel to the maximum. More than 560 grams should not be fed with the 3 liters collecting vessel and the 4 mm sieve cassette. As expected, it seems that less of fine fraction was formed with only 700 rpm speed setting.

Cleaning was performed rapidly by vacuuming with a soft brush. Also here, a few traces on the surface of the rotor were found. Those were removed with a standard rubber for pencil marks.

It is also possible to use an optional high-performance cyclone separator to guide all particles into a collecting glass and minimize losses with the powerful air stream of the sample exhauster.