Grinding is the process by which a material is broken into smaller particles. The pin mill, a grinding mill, is a popular mill used in the pharmaceutical industry. Simply put, the pin mill consists of two counter rotating discs facing each other. Pins are embedded on the inner surfaces of the mill, such that the tips of the mill face the inner surface of the opposite disc. The action of breaking down material occurs when the disc(s) spins at high speed.
The pin mill is used in the pharmaceutical industry for the uniformly small particle sizes it produces.
The material is introduced into the grinding mill through a channel in the center of the mill and moves outwards due to the centrifugal forces exerted by the spinning disc. As the material moves outwards it impacts an ever greater number of pins, becoming smaller in size, till such time it is of sufficient size and can be extracted from the bottom of the grinding mill.
Also called Centrifugal Impact Mills, pin mills offer a number of benefits over grinding mill types:
- Small particle size – Pin mills are able to break down material into smaller particle sizes than other grinding mills. Particle sizes of about 2 micrometers can be achieved.
- Uniform product – Pin mills by design output a homogeneous product.
- Dust-free – Pin mills do not expel dust during operation, saving on the nuisance-dust normally produced by grinding mills. In fact, unlike other grinding mills virtually no product is wasted.
- Lower energy consumption – Given their design, pin mills are a relatively energy-efficient grinding mill.
- Small footprint – Pin mills are a relatively small grinding mill.
- Flexible use – Pin mills can be used to mill dry or moist material. Moreover, the particle size can be altered ‘on the fly’; without having to shut the mill down.
When looking for grinding mills, the pin mill is certainly one to keep in mind.