SUMMARY
Chainsaws with chipper-type chains are widely used in timber harvesting. While existing research on such saws assumes a continuous cutting process, the objectives of the present study were to determine whether or not that is true, as well as to measure instantaneous cutting forces and active cutting time (the time during which the chainsaw cutters are actually engaged with the wood sample). Tests were conducted on a special experimental stand enabling cutting force measurement with a frequency of 60 kHz. The test material was air-dry pine wood. The feed force range was 51–118 N. The chain was tensioned. The study revealed considerable variability in instantaneous cutting force, which was correlated with the rotational speed of the chainsaw engine, as indicated by frequency analysis. Furthermore, the process of cutting with chainsaws was shown to be discontinuous, and a cutter engagement time ratio was defined as the proportion of active cutting time to the overall time of chainsaw operation when making the cut. It was also found that active cutting time was directly proportionate to the applied feed force and inversely proportionate to the rotational speed of the chainsaw engine. The results may be practically applied to establish an optimum range of rotational speed that should be maintained by the operator to maximize cutting efficiency.