New Cutting Mill SM 300 – Refinement of a Well-Proven Grinding Principle - Retsch GmbH

Cutting mills are used in many different areas of sample preparation for subsequent analyses. Typical applications include the size reduction of secondary fuels, the processing of biomass for renewable energy research, the control of products in the context of RoHS and WEEE regulations or the recovery of precious metals – the variety of sample materials is huge.

To meet all the requirements of such varied applications, the mill needs to be flexible and powerful. Even though the existing cutting mills developed by Retsch already offer a high
level of performance and operating convenience, Retsch demonstrates with the new model SM 300 that it is still possible to set a new standard for the sample preparation of medium-hard, tough-elastic and fibrous materials.

What are the advantages of the new cutting mill?

Thanks to the fold-back housing, the grinding chamber is fully accessible which, in combination with the smooth surfaces, greatly facilitates cleaning the mill after grinding. The push-fit rotor can be removed quickly and safely from the open chamber. The SM 300 can be optionally equipped with a cyclone-suction-combination. In addition to a cooling effect, it also improves the discharge of material from the grinding chamber and is therefore recommended for grinding small volumes or low density materials. The improved product flow, which was achieved by an asymmetrically arranged sample feed, and the double acting cutting bars in the grinding chamber greatly enhance the performance of the new cutting mill.

The SM 300 features a variable speed ranging from 700 rpm to 3,000 rpm which allows for optimum adaptation to the sample properties with regards to breaking behaviour and temperature sensitivity. Thus it is possible to grind a great variety of products with one mill:

• When processing circuit boards, a low speed of 700 rpm should be selected to prevent the sample from getting too warm (e.g. for detection of heavy metals such as mercury). The energy required for grinding such hard metals is gained from the high torque of 20 Nm. In addition, low speed helps to reduce wear of the grinding tools.

• A speed of 1,500 rpm combines the maximum power of 3 kW with the maximum torque of 20 Nm. This speed is ideal for all materials that are neither particularly heat sensitive nor too tough.

• The maximum speed of 3,000 rpm is suitable for materials which would otherwise not be discharged from the grinding chamber or which, due to their elasticity, could cause the rotor to slow down or stall it altogether. Due to the Rotational Energy Storage (RES) technology the SM 300 ensures successful grinding without rotor blockage, even when high throughput is required. A high torque alone would be insufficient here, so that the rotational energy stored in the flywheel mass in combination with the maximum power of 3 kW guarantees excellent grinding results.