Experimental tests of PVD AlCrN-coated planer knives on planing Scots pine (Pinus sylvestris L.) under industrial conditions

Raw pine wood processing and especially its mechanical processing constitute a significant share among technological operations leading to obtaining a finished product. Stable implementation of machining operations, ensuring long-term repeatable processing results depends on many factors, such as quality and invariability of raw material, technical condition of technological equipment, adopted parameters of work, qualifications and experience of operators, as well as preparation and properties of the machining tools used. It seems that the greatest potential in the search for opportunities to increase the efficiency of machining operations has the modification of machining tools used in it. This paper presents the results of research work aimed at determining how the life of cutting tools used in planing operations of wet pine wood is affected by the application of chromium aluminum nitride (AlCrN) coating to planar industrial planing knives in the process of physical vapour deposition. For this purpose operational tests were carried out under production conditions in a medium-sized wood processing company. The study compares the effective working time, rounding radius, the profile along the knife (size of worn edge displacement, wear area of the cutting edge), selected texture parameters of the planar industrial planing knife rake face and visual analyses of cutting edge condition of AlCrN-coated planar knives and unmodified ones. The obtained experimental results showed the possibility of increasing the life of AlCrN-coated knives up to 154% compared to the results obtained with uncoated ones. The proposed modification of the operational features of the knives does not involve any changes in the technological process of planing, does not require any interference with the machining station nor its parameters, therefore enabling rapid and easy implementation into industrial practice.