CNC drilling of wear-resistant Hardox 450 steel using HSSCo solid drills with variable feed rates
Estonian University of Life Sciences, Institute of Forestry and Engineering, Biosystems Engineering, 56 Kreutzwaldi Str., EE 51006 Tartu, Estonia
*Correspondence: Maicel.pytt@gmail.com
Abstract:
Wear-resistant martensitic plates are widely used in agricultural machinery but are difficult to drill during fabrication and repair. This study compared constant-feed and
depth-adaptive CNC drilling of 12 mm Hardox 450 using cost-effective 8 mm HSS-Co twist drills under flood cooling. Axial force was recorded in real time using a Kistler piezoelectric dynamometer and interpreted together with repeated-hole behaviour, tool-edge condition, and chip morphology. Under constant-feed drilling at Vc = 20 m min⁻¹, the maximum axial force increased from approximately 980 N in the first hole to 2130 N in the third hole.
Under the depth-adaptive feed condition at the same cutting speed, peak axial force remained at approximately 900–910 N across the three-hole sequence and was associated with a smoother breakthrough response, less visible edge deterioration, and more regular chip morphology. Within the limits of this short-run feasibility study, the results suggest that breakthrough-oriented feed reduction may reduce drilling load and support more stable breakthrough behaviour without changing the tool type or machine platform.
Key words:
adaptive feed, Agricultural machinery, axial force, drilling, wear plate, wear-resistant steel