In the production of flakes (for particleboard) and fibres (for fibreboard), a basic distinction is made between two-stage and direct size reduction.
For the two-stage reduction process, round timber and industrial waste wood (rinds, splits, cuttings, etc.) are first processed into wood chips, the so-called chipping. This is usually done in a drum chipper or disc chipper. This two-stage approach is followed by the actual flaking or grinding process in a second step.
The size of the wood chips determines the length of the later flakes or fibres. The raw material is mainly chipped in a moist state - this allows more uniform chips to be produced. It increases the yield of usable material and the energy consumption is lower. With direct flaking or grinding, chipping is not necessary.
Metal inclusions often occur in both fresh wood and recycled wood. After chipping, they are detected with a metal detector and sorted out.