A constant cutting speed and feed-per-tooth CAD/CAM algorithm in free-form milling

Ball-end milling is a fundamental process for machining free-form geometries, typically executed via parallel toolpaths over curved surfaces. Due to the continuous variation in tool-surface engagement, the effective tool diameter and cutting speed (m/min) alter, affecting the process. This study introduces CAMSpeed, a novel software routine designed to dynamically parameterise spindle speed (RPM) and feed rate (mm/min) based on real-time tool-surface contact. The goal is to maintain a consistent cutting speed and feed per tooth along the entire free-form toolpath. CAMSpeed was successfully integrated into a commercial CAD/CAM platform, and milling experiments were conducted to validate the approach. Results demonstrated that the use of parameterised NC codes reduced machining time by 28% and form error by 8%, without any increase in tool wear. Furthermore, modal analysis confirmed that the continuous variation of spindle speed did not induce machining-related forced vibrations. These findings underscore the potential of the proposed algorithm to optimise free-form milling by adaptively adjusting spindle speed and feed rate in response to geometrical complexity.