Rotor mills are used for high-speed size reduction of soft to medium-hard as well as temperature-sensitive or fibrous materials.
The powerful Ultra Centrifugal Mill ZM 300 provides maximum grinding performance combined with ease of use. The variable speed from 6,000 to 23,000 rpm allows for gentle, neutral-to-analysis sample preparation in a very short time.
Thanks to an integrated temperature monitoring system, reproducibility is guaranteed even for long grinding processes or pulverization of large sample volumes.
The wide selection of rotors, ring sieves and cassettes makes the ZM 300 a true allrounder which meets the requirements of a great variety of size reduction tasks.
"Very easy to operate the device. Relatively easy to clean after grinding (avoiding cross-contamination)."
Jaap Winkelhorst
BASF
"Grinding is very quick. We use the cyclone connection that makes the grinding process easy with large patches."
Eija Fogelholm
Finnish Customs Laboratory
"This equipment is a must have for ingredients science and application laboratories. Easy to use, low maintenance and safe to operate. It provides reproducible results. "
Petros Gebreselassie
Ashland Inc.
"The Retsch Ultra centrifugal mill is the one “grinder” that gave us the particle size and hence the best analytical result (e.g. oil content) in a variety of oilseed sample types. Over 30 years in the laboratory, allows me to call the Retsch mills/ grinders as the “gold standard” when it comes to sample preparation."
Douglas DeClercq
DRD
"This is best grinder in our Lab. We also have other brands, but the Retsch Mill is a top ranking. All stainless-steel parts are very easier to clean. "
Tai Ha
Nebraska Department of Agriculture Laboratory
"This grinder performs wonderfully. We have had ours close to 5 years and have not had an issue. We grind anywhere from 300-500 samples per week.
Mary Ann Barrett
Jennie-O Turkey Store
"Highly effective, easy to use, high quality product."
Ashley Brown
ISK Biosciences Corporation
"High quality instrument, fast processing time, easy to use and clean! "
Alec Keyzer
Bureau Veritas
The speed range from 6000 to 23000 rpm allows for optimum adaptation of the grinding process to the sample requirements by keeping the grinding time as short as possible and the temperature increase as moderate as possible. Too much heat may have a negative effect on the grinding results, for example, if moisture or volatile components escape.
The ZM 300 is equipped with an integrated temperature sensor which measures the temperature of the cassette lid near the ring sieve. The measured temperature is constantly shown in the mill’s display, allowing the user to optimize the grinding process and improve reproducibility.
The maximum speed of classic centrifugal mills, like the widely used ZM 200, is usually limited to 18,000 rpm (rotor peripheral speed 98 m/s). The ZM 300 achieves a maximum speed of 23,000 rpm (rotor peripheral speed 118 m/s) and produces particles which are 15 to 20 % finer in comparison, depending on the material.
The higher speed has a particularly positive impact on the grind sizes of polymer samples which are pulverized cryogenically, or of fibrous materials like hay. Compared to models with a maximum speed of 18,000 rpm, the throughput may be increased by 10 to 15 %.
Grind sizes of plastic materials (POM or PP) after grinding with different sieves and speeds. The speed of 23,000 rpm results in a higher fineness for all sieves compared to grinding at 18,000 rpm. For example, a 19 % reduction in fineness can be achieved when POM is ground with a 0.12 mm distance sieve at 23,000 rpm.
The maximum sample throughput, e.g. when crushing chicken feed with a 0.5 mm ring sieve, could be increased by 16% when crushing at maximum speed of 23,000 min-1 instead of 18,000 min-1.
The fines content in a pulverized sample can be controlled by speed reduction. If, for example, the grains of an animal feed sample are to be coarsely ground to avoid dust formation, a reduction to 6,000 - 10,000 rpm will provide the desired result.
Thanks to the variable speed, the ZM 300 can be flexibly adapted to all requirements in the food and feed industry, chemical industry, and in agriculture.
Cryogenic or cold grinding is the ideal solution for pulverizing samples that cannot be reduced to the required fineness at room temperature. This procedure involves the use of grinding aids such as liquid nitrogen (-196 °C, embrittlement of the sample outside the mill) or dry ice (-78 °C, sample/dry ice mixture) to embrittle the sample material by cooling, and thus improve the breaking behavior.
In addition, highly volatile components are better preserved in the sample by cooling. Cryogenic grinding is easy to perform with the ZM 300 and is recommended especially for plastics or very temperature-sensitive samples. The video shows the process with the predecessor model ZM 200, which is identical in the ZM 300.
This video shows dryice grinding of plastic granules with the ZM 200 which also applies to the ZM 300.
When operated with the optional cyclone-suction-combination, the ZM 300 is also suitable for grinding low-density or heat-sensitive sample materials.
The wide selection of accessories allows optimum adaptation to all size reduction requirements. The desired fineness is determined by the aperture size of the ring sieve. As a rule of thumb, about 80 % of the sample is about half the size of the aperture size of the selected sieve after grinding. Sieves are available with aperture sizes ranging from 0.08 to 10 mm.
For the ZM 300 ring sieves with reinforced rim are used which are equipped with four grooves for secure locking. Distance sieves, also secured and fixed by four grooves, have a gap between the sieve mesh and the rotor, which reduces shearing effects and thereby heat generation.
Rotors are available with either 6, 12 or 24 teeth. The standard rotor with 12 teeth is suitable for almost any material and requirement. For fibrous samples, such as straw, the rotor with 6 teeth is typically used, while for fine samples the rotor with 24 teeth is best suited.
For neutral-to-analysis work, or for pulverizing abrasive samples, grinding tools in various materials are available: titanium (titanium-niobium coating), steel 1.4404, tungsten carbide coating.
In the standard collecting vessel with 900 ml nominal volume, up to 300 ml of sample can be ground in one working step. With the large-volume cassette, the useful volume can be doubled to 600 ml. When utilizing a cassette with cyclone, various collecting vessels up to 4,500 ml useful volume are available.
The Vibratory Feeder DR 100 is controlled via an interface and conveys material in a load-dependent manner to the hopper of the ZM 300. This procedure ensures uniform grinding with maximum sample feed. The use of a feeder is particularly advantageous for large sample quantities.
The ZM 300 is easy and safe to operate. The large touch display with rotary knob permits convenient entry of the grinding parameters. It shows the current cassette temperature and load during grinding which helps to prevent overloads by feeding the sample too quickly.
A push-fit system without screws and the patented cassette principle allow for easy insertion and removal without tools.
As a result, cleaning rotors and ring sieves is particularly quick and easy. All parts in contact with the sample can be cleaned under running water or in the dishwasher.
The versatile Ultra Centrifugal Mill ZM 300 processes materials such as bones, cereals, chemical products, coal, coffee beans, collagen, corn, dried fruit and vegetables, dried larvae, drugs, electronic components, feed pellets, fertilizers, food, grain, graphite, minerals, paper, pharmaceutical materials, plant materials, polymers, powder coatings, rice, rubber, seeds, spices, straw, sweets, textiles, tobacco, waste, wood
powder coatings
coffee beans
PET flakes
herbs
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 | fine grinding |
| Field of application | agriculture, biology, chemistry / plastics, construction materials, engineering / electronics, environment / recycling, food, geology / metallurgy, medicine / pharmaceuticals |
| Feed material | soft, medium-hard, brittle, fibrous |
| Size reduction principle | impact, shearing |
| Material feed size* | < 10 mm |
| Final fineness* | < 40 µm |
| Batch size / feed quantity* | 300 ml with standard cassette 600 ml with volume cassette 4500 ml / 2500 ml / 450 ml / 230 ml with cyclone |
| Speed at 50 Hz (60 Hz) | 6,000 - 23,000 min-1, free selectable |
| Rotor peripheral speed | 31 - 119 m/s |
| Rotor diameter | 99 mm |
| Types of rotors | 6-tooth rotor / 12-tooth rotor / 24-tooth rotor |
| Material of grinding tools | stainless steel, titanium, stainless steel with wear-resistant coating |
| Sieve sizes | trapezoid holes 0.08 / 0.12 / 0.20 / 0.25 / 0.50 / 0.75 / 1.00 / 1.50 / 2.00 mm round holes 3.00 / 4.00 / 5.00 / 6.00 / 10.00 mm |
| Setting of grinding time | no |
| Collector capacity | 900 ml with standard cassette 1200 ml with volume cassette 5000 ml / 3000 ml / 500 ml / 250 ml with cyclone |
| Drive | 3-phase asynchronous motor with frequency converter |
| Power connection | 1-phase |
| Protection code | IP 20 |
| Power consumption | 1750 VA ((200..240V), 1400 VA (110..120V) |
| W x H x D closed | 452 x 431 x 426 mm |
| Net weight | ~ 38 kg |
| Standards | CE |
In the Ultra Centrifugal Mill ZM 300 size reduction takes place by impact and shearing effects between the rotor and the fixed ring sieve. The feed material passes through the hopper (with splash-back protection) onto the rotor. Centrifugal acceleration throws it outward with great energy and it is pre-crushed on impact with the wedge-shaped rotor teeth moving at a high speed. It is then finely ground between the rotor and the ring sieve.
This 2-step grinding ensures particularly gentle but fast processing. The feed material only remains in the grinding chamber for a very short time, which means that the characteristic features of the sample to be determined are not altered. The ground sample is collected in the collecting cassette surrounding the grinding chamber or in the downstream cyclone or paper filter bag.
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