From a revolutionary idea
proposed and developed by Dr.
Andrew Szegvari in 1945, Attritor
technology grew to become the basis
for Union Process, Inc., an
independent, family-owned American
company founded in Akron, Ohio.
Today, Attritors are considered to be
the most efficient grinding/dispersing
systems and are used in scores of industries and research
laboratories worldwide. More recently, Union Process has
developed Attritors specifically designed for the dry grinding
Continuous or Batch Operation
The SD Dry Grinding Attritors can be operated in both
continuous and batch processing applications. In the
continuous operation, the material is fed into the vessel at the
top. It then migrates through the agitating media bed where it
is processed to a desired particle size and is discharged
through metering bar grids at the bottom of the tank.
In the batch mode, material is charged into the mill at the
top, ground for a predetermined time, then discharged through
grids at the bottom. The system can easily be sealed for
grinding under inert gases such as nitrogen or argon.
The SD Attritor is also used to make dispersion-
strengthened metal (DSM). In this process (known as
mechanical alloying or cold welding), the kinematic porosity
results in the grinding media breaking the metals into small
particles and beating them together to form agglomerates. By
repeating the process, the various metals are evenly mixed
and dispersed to form a new composition of alloy (DSM).
The HSA High Speed Attritor is generally used in a
continuous mode. The material is charged into the mill at the
top and is discharged out the bottom side, making use of
centrifugal force. The HSA is used when smaller particle size
(generally 40 mesh) materials are fed into the machine and
micron size end product is desired.
Also, it is often used for fibrous and polymer types of
Dry Grinding Attritors
SD, HSA, and Lab Series
The Dry Grinding Process
The Attritor dry grinding process is achieved in a
stationary tank by means of a rotating shaft and arms that
agitate the media into a random state of motion of internal
porosity called kinematic porosity. In this expanded condition,
the media and particles are free to move, collide and impinge
upon each other.
MEDIA AT REST
Revolving arm hits