| Edge deterioration of woodcutting tools causes low productivity, poor wood surface finish, high power consumption, sawing variation and kerf losses. It is a continual problem in every wood machining operation, yet the mechanisms are not fully understood. A good understanding of the mechanisms and their relative magnitude would lead to a better selection of existing tool materials and the development of new materials, and ultimately a higher yield/cost ratio.; A study was performed on various commercial woodcutting tools from several sawmills, emphasizing surface characteristics to examine the deterioration phenomena. The knowledge gained from the field study was then applied towards the development of a laboratory woodcutting test which mimicked the field behavior. Four types of cutting edge materials, a steel, high speed steel, cemented carbide and Stellite{dollar}sp{lcub}rm TM{rcub}{dollar} were used to cut Douglas fir, western red cedar and Oregon white oak, with various moisture contents. Interrupted tests were performed to monitor the progression of edge wear, and edge width and weight loss measurements were used to evaluate the degree of wear.; Abrasion and corrosion were found to be the two major edge wear mechanisms. Either one could be dominant depending on cutting edge materials, wood species and moisture content. For example, abrasion was dominant when Douglas fir was cut, and dry fir caused greater wear than green fir. Green cedar, however, caused more wear to the steel and the cemented carbide, and corrosion was found to be the predominant mechanism. Dry cedar, nevertheless, resulted in little wear to the same carbide. The Stellite{dollar}sp{lcub}rm TM{rcub}{dollar} exhibited superior overall performance than the steel, high speed steel and cemented carbide, and showed no sign of wear cutting green cedar. Fracture and thermal effects were found only in very specific conditions, and are believed to have little effect on the overall cutting edge deterioration.; The edge width measurement was found to be an effective and reliable method for evaluating the degree of edge wear, and was particularly useful for interrupted tests. The weight loss measurement, however, was not reliable since weight loss from areas other than the cutting edge also contributed to the total measured results. |
