Sizing

Technology
Technology details
Name:	Sizing
Category:
Feedstock:	straws, wood, wastes
Product:

Sizing is a mechanical process to change the size of a material to use it in a conversion process. This normally means that a base feedstock with bigger parts is reduced to smaller pieces. Sizing includes chipping and grinding as base technologies.

Feedstock

Sizing is a pre-treatment technology for nearly all materials that consist of larger parts like straws, wood pieces, plant fibres and other materials. It is needed to prepare smaller particles that can be processed in further steps.

Process and technologies

Sizing technologies normally are devided into chipping or grinding technologies:

Chipping

For chipping normally a chipper machine is used that consists of sharp cutting knives, that slice bigger parts into smaller chips. This is used e.g. for wood materials, straws, mixed garden residues and other feedstock that can be cutted by a knife. Chippers are susceptible to knife wear from high soil content, metal contamination, rocks and stone, so the base feedstock normally needs to be cleaned before chipping.

Grinding

For grinding normally a grinder is used that cracks bigger parts into smaller particles. Grinding is achieved by shearing and/or friction and the grinding effect is achieved by multiple comminution in an increasingly narrowing grinding gap, which can usually be varied by axial displacement of a rotor or stator.

Product

Products of sizing processes are chips, small particles or meals that can be directly used in a following process.