Pin milling can be used on a variety of grains and cereals.

Pin Milling

What is Pin Milling?

Pin milling is a size-reduction technology often used as an auxiliary grinding mechanism in flour mills and analytical laboratories. Pin mills use metal disks fitted with pins to efficiently and quickly break up materials.1

Compared to roller mills, pin mills offer the milling industry a means for reducing the size of cereal kernels in a relatively short time, thus achieving almost complete comminution of endosperm chunks with minimum starch damage.2

How does pin milling work?

A pin mill is a single-passage-type mill that takes the form of two discs or plates which are placed together on a common spindle or shaft and are separated by a small adjustable gap or clearance. The discs are designed to rotate at high speed (up to 10,000 rpm) using a powerful electric motor. The inner face of both disks are fitted with circular or concentric rows of hardened steel projections (known as pegs, teeth or pins). The pin rows of one disk fit alternately into the rows of the other disk, and provide enough shear and impact forces to comminute feed materials into fine or coarse granular products.3,4

Disk sets in pin mills can have two different operating configurations:4

  1. One of the disks is maintained static (called stator) while the other is rotated (called rotor).
  2. Both disks may rotate either in the same or in opposite directions at different speeds.

The incoming material is gravity fed through the centrally located inlet of the stator disc. Centrifugal forces accelerate the materials in such a way that they reach the striking zone where they are subjected to strong impact and shear forces between the pins.

Pin mills may have a filter screen of a given mesh or aperture opening fitted over the whole or part of the equipment periphery. After grinding, the reduced particles are forced to pass through the screen from where they are collected and discharged. Pin mills may be fitted with jackets for temperature control. Such mills are suitable for heavy duty operations, and grinding to maximum fineness.4

Size reduction efficiency with...

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