Effect of skew angle on main precursor of frictional ignition in bench-scale simulation of excavation processes

•Temperature changes (ΔT) of cutting tool driven against a rock wheel were examined.•Long-duration tests increased ΔT at non-zero skew angles.•Heavier bits with larger tip surface area are more sensitive to ΔT increase due to skew angle.•ΔT at a zero skew angle was higher for lighter bits.•The results suggest how bits and bit tips should be designed for safer excavation.