Ultra Centrifugal Mill

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 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.

Short processing times – Avoid excessive heat generation and motor overload

The speed range from 6,000 to 23,000 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 ULTRA CENTRIFUGAL MILL 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.

Finer end products and higher sample throughput

Application examples

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.

Cryogenic Grinding

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 ULTRA CENTRIFUGAL MILL and is recommended especially for plastics or very temperature-sensitive samples.

Ideal for light & heat-sensitive materials

In combination with the cyclone suction unit, the Ultra Centrifugal Mill is even suitable for grinding light and heat-sensitive materials.

• Efficient cooling of sample and grinding tools
• Improved sample discharge from the grinding chamber
• Particularly suitable for large volumes
• The cyclone accommodates sample bottles of 0.25, 3 and 5 liters
• Ideal for cryogenic grinding

Accessories for ULTRA CENTRIFUGAL MILL

Comprehensive selection for individual requirements

The wide range of accessories makes the ULTRA CENTRIFUGAL MILL extremely versatile. The desired final fineness can be determined by selecting the ring sieve. Rule of thumb: After grinding, approximately 80% of the sample material is about half the size of the sieve aperture. You can choose between sieves with apertures ranging from 0.08 to 10 mm.

Ring sieves

For the ULTRA CENTRIFUGAL MILL 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

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.

Heavy-metal-free grinding

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.

Collecting vessels

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.

Convenient operation – easy cleaning

In the Ultra Centrifugal Mill , 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.

Typical Sample Materials

The ULTRA CENTRIFUGAL MILL is suitable for grinding a wide variety of materials:
waste, graphite, collagen, drugs, fertilizers, feed pellets, grains, spices, rubber, wood, coffee beans, bones, coal, food, corn, minerals, paper, plant parts, polymers, powder coatings, rice, seeds, straw, sweets, tobacco, textiles, chemical products, electronic components, dried fruits and vegetables, dried larvae, pharmaceutical products.

Functional Principle

The grinding process is carried out by impact and shearing forces between the rotor and the fixed ring sieve. The sample material is fed into the rotor via a funnel with splash protection, accelerated outwards by centrifugal force, and pre-ground by the wedge-shaped rotor teeth. The subsequent fine grinding takes place in the narrow gap between the rotor and the sieve.

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 °m

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 30

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