Cotton fibre is compressed in a bale of 200 to 250 kg. This highly compressed cotton fibre need to be opened at first as a part of yarn manufacturing. And there is 1.5% to 7% trash in a cotton bale which is also needed to be removed before further processing. This process of opening & cleaning is known as blow room process. Blow room consists of a number of m/c used in succession to open & clean the cotton fibre to the required degree. 40% to 70% of the total trash is removed in this section.
1. Opening: To open the compressed bales of fibres & To make the cotton tuft a small size as far as possible.
2. Cleaning: To remove the dirt, dust, broken seeds, broken leaves, stalks and other foreign materials from the fibres.
3. Blending or Mixing: To make good value of yarn and to decrease the production cost by mixing different grade of fibres.
4. Lap forming: To transfer the opened and cleaned fibres into a sheet form of definite width and uniform unit length which is called a lap.