AHMAD QAYYUM

M13-CE-04

KNIFE MILL

TABLE OF CONTENTS Definition Principle Basic parts Construction & Working Applications Advantages Disadvantages

DEFINITIONA mill in which knifes are attached on the impeller that crushes the aggregate material and converts it into the fine range particles is called Knife mill.

PRINCIPLEThe size reduction of the materials is done by cutting with the help of sharp knifes which provides shearing action rather than impact or attrition and converts the feed into fine size particles which is collected from discharge chute.

WHY WE USE KNIFE MILL ?

Sometimes, the feed stocks are too tenacious or too resilient to be broken by compression , impact or attrition. And sometimes, feed must be reduced to particles of fixed dimensions. So, these requirements are met by knife cutter that cut, chop and tear the feed into the product with the desire characteristics.

BASIC PARTS Feed hopper Casing Rotor / Impeller Stationary knives Moving knives Screening plate

CONSTRUCTION

There are two types of knifes, stationary which is fixed with casing and other is rotating which is attached to the rotor.

The upper part of casing also contains a hopper inlet, whereas the lower part has screen of desired aperture size.

The rotary knife cutter has 2 to 12 knives on its periphery that rotates with 200 to 900 rpm and the cylindrical casing has several knives.

WORKING The material to be cut is put into the hopper. The feed size should be less than 1 inch and should not

exceed the length of cutting knifes. Due to the rotation of rotor, feed comes very close between

the stationary and moving knives. It cuts down the material into the small pieces.

Screen retains the material in the mill until the desired product is formed. The product is collected which comes out of the sieve.

APPLICATIONS

Combine Harvester/ Thresher Lawn Mower ( Grass cutting machine )

ADVANTAGES

Knife mill produces ultrafine particles and yield narrow size distribution.

It is easy to install. The speed can rapidly changed by rotating the knives. Moreover, maintenance is easy and inexpensive.

DISADVANTAGES

It is not easy to clean. Speed should be controlled. Wet preparation of the materials can not be sieved due to

clogging of the materials take place. Feed thickness should not be more than the thickness of

cutting knifes.