Keyway CNC planer : determining machining force

Abstract

This thesis investigates the cutting forces generated during vertical slotting of keyways using a custom cutting tool holder provided by Astex Engineering Oy. The goal was to determine whether high cutting forces (axial and bending forces) were responsible for poor surface quality and dimensional inaccuracies in wider keyways. Force measurements were carried out using a strain gauge-based method, which allowed both axial and bending forces to be calculated from the strain values on the cutting tool holder during slotting operations.

The experiments showed that increasing the cutting speed generally led to lower cutting forces, while a higher radial engagement significantly increased bending forces. These increased forces were linked to tool deflection, which likely contributed to the observed quality issues. The study confirmed that cutting parameters such as stepover had a strong influence on force levels, and therefore directly impact machining performance.

The results support the use of strain gauges for force estimation in slotting and provide valuable input for future tool and slotting machine design. This work fills a gap in the limited research on vertical slotting and offers practical insights for improving machining accuracy and surface finish through optimized cutting conditions.