Three roll mill
Encyclopedia
A three roll mill is a machine that uses shear force created by three horizontally positioned rolls rotating in opposite directions and different speeds relative to each other, in order to mix, refine, disperse, or homogenize
viscous materials fed into it.
, is fed between the feed roll and the center roll. Due to the narrowing space between the rolls, most of the paste is rejected to the feed region. The part that makes it through the first in-running nip experiences very high shear force. Upon exiting, the material that remains on the center roll moves through the second nip between the center roll and apron roll, which subjects it to even higher shear force due to the higher speed of the apron roll. A knife blade then scrapes the processed material off the apron roll and transfers it to the apron. This milling
cycle can be repeated several times to maximize dispersion
.
The gaps between the rolls can be mechanically or hydraulically adjusted and maintained. Typically, the gap distance is far greater than the particle size. In some operations, the gap distance is gradually decreased to achieve the desired level of dispersion.
, plastisol
s, carbon
/graphite
, paints, printing inks, pharmaceuticals, chemicals, glass coatings, dental composites, pigment
, coatings, adhesives, sealants, and foods. With the recent development in technology, they are also utilized in the production of cable cover, electronics, soap
, and artificial plastics.
Small bench models are used for bench-top development work, laboratory work, and low volume production. Larger bench and floor models are built to meet different production needs from pilot plants to large volume productions.
Mikrons
Charles Ross & Son Company
Sigma Equipment Corp.
Homogenization (chemistry)
Homogenization or homogenisation is any of several processes used to make a chemical mixture the same throughout.-Definition:Homogenization is intensive blending of mutually related substances or groups of mutually related substances to form a constant of different insoluble phases to obtain a...
viscous materials fed into it.
Operation of a three roll mill
The three adjacent rolls of a three roll mill (called the feed roll, centre roll and apron roll) rotate at progressively higher speeds. Material, usually in the form of pastePaste
Paste may refer to:*Wheatpaste, also known as potato paste, flour paste, rice paste, Marxist glue, or simply paste, made from vegetable starch and water*Paste , a Mexican pastry*Paste , an American music and entertainment magazine...
, is fed between the feed roll and the center roll. Due to the narrowing space between the rolls, most of the paste is rejected to the feed region. The part that makes it through the first in-running nip experiences very high shear force. Upon exiting, the material that remains on the center roll moves through the second nip between the center roll and apron roll, which subjects it to even higher shear force due to the higher speed of the apron roll. A knife blade then scrapes the processed material off the apron roll and transfers it to the apron. This milling
Milling machine
A milling machine is a machine tool used to machine solid materials. Milling machines are often classed in two basic forms, horizontal and vertical, which refers to the orientation of the main spindle. Both types range in size from small, bench-mounted devices to room-sized machines...
cycle can be repeated several times to maximize dispersion
Dispersion
Dispersion may refer to:In physics:*The dependence of wave velocity on frequency or wavelength:**Dispersion , for light waves**Dispersion **Acoustic dispersion, for sound waves...
.
The gaps between the rolls can be mechanically or hydraulically adjusted and maintained. Typically, the gap distance is far greater than the particle size. In some operations, the gap distance is gradually decreased to achieve the desired level of dispersion.
Application
Three roll mills are widely used to mix electronic thick film inks, high performance ceramics, cosmeticsCosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
, plastisol
Plastisol
Plastisol is a suspension of PVC particles in a plasticizer; it flows as a liquid and can be poured into a heated mold. When heated to around 177 degrees Celsius, the plastic and plasticizer mutually dissolve each other. On cooling the mold below 60 degrees C, a flexible, permanently plasticized...
s, carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
/graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
, paints, printing inks, pharmaceuticals, chemicals, glass coatings, dental composites, pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
, coatings, adhesives, sealants, and foods. With the recent development in technology, they are also utilized in the production of cable cover, electronics, soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
, and artificial plastics.
Small bench models are used for bench-top development work, laboratory work, and low volume production. Larger bench and floor models are built to meet different production needs from pilot plants to large volume productions.
Production run rate
The larger diameter rollers provide more shear force and a higher production run rate.| Roller Diameter X Roller Effective Length | RPM on Exit Roll | Gallons/hr | Lbs/hr |
|---|---|---|---|
| 2.5″X5″ | 174 | 0.25-1.25 | 1.0-5.0 |
| 6″X12″ | 217 | 1.8-8.8 | 9.0-44.0 |
| 9″X20″ | 170 | 3.5-17.2 | 14.0-68.8 |
| 12″X30″ | 170 | 7.1-34 | 28.4-136 |
| 16″X32″ | 157 | 9.0-45 | 36.0-180 |
Manufacturers of three roll mills
Torrey Hills TechnologiesMikrons
Charles Ross & Son Company
Sigma Equipment Corp.