THE NEW PLANETARY BALL MILL PM 300
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Retsch GmbH Retsch-Allee 1-5 42781 Haan Germany Phone 02104/2333-100 E-Mail info@retsch.com THE NEW PLANETARY BALL MILL PM 300 INCREASED THROUGHPUT MEETS EASY HANDLING Planetary ball mills meet and exceed all requirements for fast and reproducible grinding to analytical fineness. They are used for the most demanding tasks in the laboratory, from routine sample processing to colloidal grinding and advanced materials development. With the new PM 300 RETSCH has developed a powerful tool which offers high sample throughput combined with ease-of-use. Fig. 1: Planetary Ball MIll PM 300 Thanks to extremely high centrifugal forces which result in very high pulverization energy, planetary ball mills process soft, hard, brittle, and fibrous materials in dry or wet mode in a very short time. They are ideally suited for tasks in research, like mechanochemistry (mechano-synthesis, mechanical alloying and mechanocatalysis), but also for ultrafine colloidal grinding on a nanometer scale. A crucial advantage of planetary ball mills is their great versatility: They are available with different numbers of grinding stations and can be operated with jars and balls of various sizes and materials. The ”Planetary” Principle In the planetary ball mill, every grinding jar represents a “planet”. This planet is located on a circular platform, the so-called sun wheel. When the sun wheel turns, every grinding jar rotates around its own axis, but in the opposite direction. Thus, centrifugal and Coriolis forces are activated, leading to a rapid acceleration of the grinding balls. The result is very high pulverization energy allowing for the production of very fine particles. The enormous acceleration of the grinding balls from one wall of the jar to the other produces a strong impact effect on the sample material and leads to additional grinding effects through friction. For

colloidal grinding and most other applications, the ratio between the speed of the sun wheel and the speed of the grinding jar is 1: -2. This means that during one rotation of the sun wheel, the grinding jars rotate twice in the opposite direction. Operation and Accessories With the development of the Planetary Ball Mill PM 300 RETSCH has closed a gap in the product portfolio. This benchtop model with two grinding stations accepts grinding jar volumes up to 500 ml which results in a maximum batch size of 2 x 220 ml sample material. Thanks to the maximum speed of 800 rpm and the enormous...

The larger sun wheel has less effect on the result than the maximum speed of 800 rpm as compared to 650 rpm for, e. g., a PM 200, see Figure 5. The results achieved in the PM 300 using a 50 ml grinding jar and 4 x 20 ml grinding balls to pulverize granite samples are only marginally better compared to the process in the PM 200; both mills were operated with 650 rpm. When the speed in the PM 300 was increased to 800 rpm, the obtained particle size was 40 % finer. A similar effect has been observed while grinding glass particles with 3 x 20 mm balls. Here, the increased speed resulted in a...

Three lid diameters for all jars: I Diameter 1: 12 ml and 25 ml jar I Diameter 2: 50 ml, 80 ml and 125 ml jar I Diameter 3: 250 ml and 500 ml jar With the new EasyFit grinding jar line, more options for jar materials and volumes for aeration lids or the temperature and pressure measurement system GrindControl have been realized. Both the aeration lid and GrindControl can now be equipped with inlays of different materials. Thus, the lid can be used for, e. g. a steel and a zirconium oxide jar by simply exchanging the inlay. Advantages of the EasyFit jar line: I Safe clamping thanks to...

Fibers left Fibers left Perfectly homogeneous Fig. 9: Grinding results of dried plant samples in the different jar geometries in the PM 100 and PM 300.. Images on the left: sample milled in old jar design (PM 100) Images on the right: sample milled in new flat jar design (PM 300) with better results Further options Aeration lids are the accessories of choice if the grinding process needs to be performed under inert conditions, for example under argon atmosphere, because oxygen affects the mechanochemical reaction inside the jar or the grinding process itself. Fig. 10: GrindControl system on...

MILLING SIEVING ASSISTING Conclusion With the powerful, ergonomic benchtop Planetary Ball Mill PM 300 RETSCH covers a wide range of size reduction applications and increases the throughput thanks to two grinding stations for jars up to 500 ml. It is also suitable for pulverizing small sample volumes down to 3 ml. With the new grinding jar line EasyFit and new options for the GrindControl system and aeration lids this mill opens up new possibilities in ball milling. part of VERDERtw scientific