Series 15 drum chippers are stationary machines provided with a horizontal feed unit. In order to grant an optimal shredding process these are available with two different rotor systems. The first rotor system works with a fast rotating chipping knife for shredding short or long lengths of waste wood, free from tramp material, from the timber sizing and wood processing industry in order to produce a defined homogeneous and continuous wood chip. The second rotor system works with a slow-turning rotor that is designed with a ribbed profile rotor with cutting crowns. Furthermore, a toothed counter knife is used with this version. This solution is used for the shredding of waste wood and timber by-products from the wood processing industry.