Effects of Four Base Cutter Blade Designs on Sugarcane Stem Cut Quality

Abstract

Abstract. The cut quality of sugarcane stems during harvesting is of considerable importance, as any damage inflicted on the stems and root systems affects ratooning and reduces yield. In current conventional cutting systems for sugarcane, relatively little attention has been paid to optimizing the cutting dynamics by investigating various blade designs and configurations. One limitation of impact cutting methods is the relatively rapid blunting of the blade edges through wear, leading to stem damage. This study aimed at investigating the effects on sugarcane cut quality of four base cutter blade designs: a conventional straight blade, a 30° angled blade, a serrated blade, and a straight blade with laser cladding on its underside. Blades of each type were installed at a 45° angle on a base cutter fitted to a John Deere 3520 sugarcane harvester. Stem damage, root system damage, and stubble height were considered as cut quality indicators, and blade wear was evaluated as the percentage of metal mass loss after completing each harvesting operation. In this study, the extent of stem and root system damage was classified into nine categories: (1) undamaged stem, not uprooted, (2) undamaged stem, partially uprooted, (3) undamaged stem, uprooted, (4) partially damaged stem, not uprooted, (5) partially damaged stem, partially uprooted, (6) partially damaged stem, uprooted, (7) severely damaged stem, not uprooted, (8) severely damaged stem, partially uprooted, and (9) severely damaged stem, uprooted. The highest percentage of stems damaged during harvesting (approx. 38%) and the highest percentage of root systems damaged (approx. 36%) occurred with the angled blade. The percentages of undamaged stems for the straight, angled, serrated, and laser clad blades were 76.9%, 62.1%, 83.1%, and 72.3%, respectively; partially damaged stems were 11.25%, 21.97%, 11.29%, and 17.73%, respectively; and severely damaged stems were 11.9%, 15.9%, 5.65%, and 9.9%, respectively. Except for the angled blade, all the blades cut almost 80% of stems without affecting the root system, and only 5% of stems were uprooted. Indices for stem damage and uprooting damage were calculated to evaluate the cut quality on a scale from -1.00 (least damage) to +1.00 (greatest damage). For both indices, the serrated blade had values closest to the target value of -1.00, implying the least damage to stems and root systems. Greater stubble heights (110 mm) were observed for the angled blade, with 76% of cut stems above the target 75 mm threshold, which was selected based on the farmer’s suggestion. Comparatively less stubble height was obtained with the serrated and laser clad blades, and roughly 60% of stems were cut in the ideal range (<75 mm). Blade wear percentages per ha of harvested area, based on metal mass loss, were found to be 0.76% for the laser clad blade, 0.83% for the serrated blade, and 0.84% for the straight blade. No mass loss data were collected for the angled blade as it caused such a high level of stem damage that its test was discontinued. The results of this study classified the levels of stem and root system damage occurring in the field during harvesting and their effects on ratooning for four base cutter blade designs. Fundamental guidelines for optimal blade configurations associated with sugarcane harvesting are provided. Keywords: Blade wear, Stem damage, Stubble height, Sugarcane harvester.