The Planetary Ball Mill PM 200 is a powerful benchtop model with 2 grinding stations for grinding jars with a nominal volume of 12 ml to 125 ml.
The extremely high centrifugal forces of Planetary Ball Mills result in very high pulverization energy and therefore short grinding times.
The PM 200 can be found in virtually all industries where the quality control process places the highest demands on purity, speed, fineness and reproducibility.
The mill is ideally suited for tasks in research like mechanochemistry (mechano-synthesis, mechanical alloying and mechanocatalysis), or ultrafine colloidal grinding on a nanometer scale, as well as for routine tasks such as mixing and homogenizing soft, hard, brittle or fibrous materials.
Benefit from particularly ergonomic handling while achieving the same finenesses down to the nanometer range.
Operation of the RETSCH planetary ball mills is particularly safe. They feature a robust Safety Slider which ensures that the mill can only be started after the grinding jar has been securely fixed with a clamping device. The self-acting lock ensures that the jar is seated correctly and securely. This proven solid mechanical system is less failure-prone than electronic solutions - the user has full access to the sample at any time. When the electronic system fails, it is not possible to unlock the jars, for example.
Wet grinding is used to obtain particle sizes below 5 µm, as small particles tend to get charged on their surfaces and agglomerate, which makes further grinding in dry mode difficult. By adding a liquid or dispersant the particles can be kept separated.
To produce very fine particles of 100 nm or less (nano-scale grinding) by wet grinding, friction rather than impact is required. This is achieved by using a large number of small grinding balls which have a large surface and many friction points. The ideal filling level of the jar should consist of 60 % small grinding balls.
For more details on jar filling, wet grinding and sample recovery watch the video.
The video shows wet grinding in the Planetary Ball Mill PM 100.
The graphic shows the result of grinding barium titanate at 500 rpm in the PM 200. After 5 h of pulverization in heptane and oleic acid mixture with 0.5 mm grinding balls, the D90 value of the original sample was reduced from 15 µm to 95 nm.
Grinding of barium titanate in heptane and oleic acid mixture with 0.5 mm grinding balls.
Blue curve: original sample; green curve: pulverized sample after 5 h.
The performance and the result of sample preparation are also determined by the choice of the grinding jar and its ball charge. The EasyFit range of jars has been specially designed for extreme working conditions such as long-term trials, even at maximum speed of 800 rpm, wet grinding, high mechanical loads and maximum speeds as well as for mechanical alloying. This line of jars is suitable for all RETSCH planetary ball mills.
The new EasyFit grinding jar series features a structure on the bottom of the 50-500 ml jars called Advanced Anti-Twist (AAT). This ensures that the jars are tightly fixed without the risk of twisting, even at high speed, and that wear and tear is drastically reduced. Secure clamping of the jars is made much easier: to find the correct clamping position, a maximum twist of 60° is required.
The geometry of the EasyFit jars in the 50 ml and 250 ml sizes has been enlarged in diameter and reduced in height compared to the previous "comfort" models. This offers two advantages: better grinding results and interchangeable lids, as there are only three diameter dimensions for the entire grinding jar range.
Diameter categories
To produce optimum grinding results, the jar size should be adapted to the sample amount to be processed. The grinding balls are ideally sized 3 times bigger than the largest sample piece. Following this rule of thumb, the number of grinding balls for each ball size and jar volume is indicated in the table below. To pulverize, for example, 50 ml of a sample consisting of 3 mm particles, a 125 ml jar and grinding balls sized at least 10 mm or larger are recommended. According to the table, 30 grinding balls are required.
| Grinding jar nominal volume |
Sample amount | Max. feed size | Recommended ball charge (pieces) | ||||||
| Ø 5 mm | Ø 7 mm | Ø 10 mm | Ø 15 mm | Ø 20 mm | Ø 30 mm | ||||
| 12 ml | up to ≤5 ml | <1 mm | 50 | 15 | 5 | - | - | - | |
| 25 ml | up to ≤10 ml | <1 mm | 95 – 100 | 25 – 30 | 10 | - | - | - | |
| 50 ml | 5 – 20 ml | <3 mm | 200 | 50 – 70 | 20 | 7 | 3 – 4 | - | |
| 80 ml | 10 – 35 ml | <4 mm | 250 – 330 | 70 – 120 | 30 - 40 | 12 | 5 | - | |
| 125 ml | 15 – 50 ml | <4 mm | 500 | 110 – 180 | 50 – 60 | 18 | 7 | - | |
| 250 ml | 25 – 120 ml | <6 mm | 1100 – 1200 | 220 – 350 | 100 – 120 | 35 – 45 | 15 | 5 | |
| 500 ml | 75 – 220 ml | <10 mm | 2000 | 440 – 700 | 200 – 230 | 70 | 25 | 8 | |
The table shows the recommended charges (in pieces) of differently sized grinding balls in relation to the grinding jar volume, sample amount and maximum feed size.
RETSCH planetary ball mills are perfectly suitable for size reduction of, for example, alloys, bentonite, bones, carbon fibres, catalysts, cellulose, cement clinker, ceramics, charcoal, chemical products, clay minerals, coal, coke, compost, concrete, electronic scrap, fibres, glass, gypsum, hair, hydroxyapatite, iron ore, kaolin, limestone, metal oxides, minerals, ores, paints and lacquers, paper, pigments, plant materials, polymers, quartz, seeds, semi-precious stones, sewage sludge, slag, soils, tissue, tobacco, waste samples, wood, etc.
Medium-hard: biomass
35 g sample
125 ml stainless steel grinding jars
7 x 20 mm stainless steel grinding balls
15 min at 500 rpm
Brittle: tin sulfide
52 g sample
125 ml agate grinding jars
50 x 10 mm agate grinding balls
60 min at 550 rpm
10 min intervals and direction reversal
Fibrous: straw
7 g sample
125 ml zirconium oxide grinding jars
50 x 10 mm zirconium oxide grinding balls
40 min at 300 rpm
10 min intervals and direction reversal
Hard: natural rocks
60 g sample
125 ml stainless steel grinding jars
7 x 20 mm stainless steel grinding balls
10 min at 420 rpm
To find the best solution for your sample preparation task, visit our application database.
Our instruments are recognized as the benchmark tools for a wide range of application fields in science and research. This is reflected by the extensive citations in scientific publications. Feel free to download and share the articles provided below.
| Applications | pulverizing, mixing, homogenizing, colloidal milling, mechanical alloying, mechanosynthesis, nano grinding |
| Field of application | agriculture, biology, chemistry, construction materials, engineering / electronics, environment / recycling, geology / metallurgy, glass / ceramics, medicine / pharmaceuticals |
| Feed material | soft, hard, brittle, fibrous - dry or wet |
| Size reduction principle | impact, friction |
| Material feed size* | < 4 mm |
| Final fineness* | < 1 µm, for colloidal grinding < 0.1 µm |
| Batch size / feed quantity* | max. 2 x 50 ml |
| No. of grinding stations | 2 |
| Speed ratio | 1 : -2 |
| Sun wheel speed | 100 - 650 min-1 |
| Effective sun wheel diameter | 157 mm |
| G-force | 37.1 g |
| Type of grinding jars | EasyFit, optional areation covers, safety closure devices |
| Material of grinding tools | hardened steel, stainless steel, tungsten carbide, agate, sintered aluminum oxide, silicon nitride, zirconium oxide |
| Grinding jar sizes | 12 ml / 25 ml / 50 ml / 80 ml / 125 ml |
| Stackable grinding jars | 12 ml / 25 ml |
| Setting of grinding time | digital, 00:00:01 to 99:59:59 |
| Interval operation | yes, with direction reversal |
| Interval time | 00:00:01 to 99:59:59 |
| Pause time | 00:00:01 to 99:59:59 |
| Storable SOPs | 10 |
| Measurement of input energy possible | Yes |
| Interface | RS 232 / RS 485 |
| Drive | 3-phase asynchronous motor with frequency converter |
| Drive power | 750 W |
| Electrical supply data | different voltages |
| Power connection | 1-phase |
| Protection code | IP 30 |
| Power consumption | ~ 1250 W (VA) |
| W x H x D closed | 640 x 480 (780) x 420 mm |
| Net weight | ~ 76 kg |
| Standards | CE |
| Patent / Utility patent | SafetySlider (DE 202008008473) |
The grinding jars are arranged eccentrically on the sun wheel of the planetary ball mill. The direction of movement of the sun wheel is opposite to that of the grinding jars in the ratio 1:-2.The grinding balls in the grinding jars are subjected to superimposed rotational movements, the so-called Coriolis forces.
The difference in speeds between the balls and grinding jars produces an interaction between frictional and impact forces, which releases high dynamic energies. The interplay between these forces produces the high and very effective degree of size reduction of the planetary ball mill.
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