Using disposable chipper knives to decrease wood fuel processing cost

•Large stray material can cause severe damage to conventional set-ups.•Disposable knives may avoid such severe damage.•Replacement time is 15% shorter with disposable knives, when using manual tools.•Similar benefits are obtained with a swing-away counter-knife and a pneumatic wrench.•Disposable knives allow a 30% saving in knife-related cost.

For many years, tool manufacturers have proposed disposable micro-knives as a solution to both the vulnerability and the frequent maintenance problems of standard full-size knives. The study compared disposable micro-knives and standard full size-knives for replacement time and management costs. It also quantified the cost of severe damage caused to conventional knife set-ups, following accidental introduction of metal contaminants inside the chipper. In this case, damage can amount to over 30,000 €. Adoption of disposable micro-knives may avoid such severe damage and mitigate its consequences. The simpler replacement procedure also allows a 15% reduction of knife replacement time, compared with the standard knife option. On the other hand, these same benefits are also obtained with other measures, such as the adoption of a swing-away counter-knife and the use of a pneumatic wrench for knife replacement. However, disposable micro-knives do offer a significant reduction of knife-related cost, due to an extended sharpness retention. Savings may amount to 30% of the knife-related cost of a conventional knife set, or about 18 Euro cents per tonne. Further studies should investigate the reasons for the better performance of micro-knives, with a view in improving the durability of both knife types.