Low-temperature ion nitriding used for improving the durability of the steel knives in the wood rotary peeling

Abstract

In the production of veneer, the knives used in the rotary cutting of wet wood at a speed of about 1–2 m s −1 are made of low-alloy steels. These steels are used because of economical reasons, but, since they have a low tempering temperature (up to 300 °C), problems arise in treating their surface by the CVD and PVD methods which, to ensure the desired adhesion of the layers, require that the temperature of the substrate should exceed 500 °C. In view of the high friction coefficient of wet wood in contact with steel, the anti-abrasive layers must have an excellent adhesion and should be sufficiently thick. These are properties that can be difficult to obtain in combination at temperatures lower than 500 °C. The present study investigates low-temperature ion nitriding of 60SMD8 steel cutting knives. The service life of these nitrided knives, when used for the peeling of beech wood, increased by 100%.