For any forest harvesting operations, either chainsaws or barsaws in harvesting heads are pivotal tools for felling and processing the trees. These cutting chains can only run on the bar if they are lubricated to avoid excessive wear and deterioration of the machinery. Lubrication of chainsaws and harvesting heads work on a total loss system, meaning that any chainbar oil will be discharged into the environment. Mineral oil is currently predominantly used in New Zealand as lubricants, but mineral oil can be toxic to the natural ecosystems, and the people who use it. This highlights the need to investigate alternative, more environmentally friendly lubrication options for cutting systems within the forestry industry such as bio-oils made from plant material (usually rape seed). Benefits that are claimed for bio-oil include a reduction in oil flow by up to 50% without any added wear, that it is more environmentally friendly and degrades within 28 days, is better for the machinery, and people that use them. Bio-oil is however almost double the price of standard mineral oil deterring many contractors from considering using it.

In this study nine contractors from around New Zealand trialled bio-oil for a one-month period. There were surveys sent to the contractors to get pre-trial and post-trial data on the bio-oil; the contractor’s oil usage for both mineral and bio-oils and any other benefits they saw from the change to bio-oil. The second part of this study involved measuring the heat produced off the tip of the bar of the chainsaw to see what effect the two different oils had on cutting temperature. The flow of both oils on to the chain and bar was reduced to test the extent that oil-flow can be reduced before added wear becomes a risk.

All crews were able to reduce lubrication oil consumption with an average of 39%. However, there was a large variance in oil reduction, ranging from the maximum reduction seen was 51% to a low of 16%. From this an average cost saving from the contractor trial was 6%, with a maximum saving of 19%.

In the chainsaw trials where bar heat was measured under standardised test conditions, the lubrication was reduced for both oil types. The bio-oil was able to be reduced by 50% before an increase in heat was seen. The mineral oil however, was unable to be reduced from full flow before temperature increased. When the bio-oil flow was reduced by 50%, and the mineral oil unchanged at 0%, they ran at very similar temperatures (p-value of 0.48). This demonstrated that the bio-oils were able to be made cost competitive against mineral oils whilst not adding any extra wear to the chainsaw.

This study highlights the benefits of bio-oil and the possibilities of its industry application. It demonstrates a local example to New Zealand contractors of how bio-oil can be used in operations without any added wear or stress on machinery, in addition to its cost saving and environmental benefits. This dissertation can also be used as a basis for bio-oil policy within New Zealand forest management companies; especially in high risk areas such as waterways or near native remnants.