According to the kinematics of the cutting tool, two different machining operations occur in helical milling operation. One is the plunge milling machined by its front cutting edges resulting from the axial feed of the cutting tool, the other is the peripheral milling machined by its side cutting edges resulting from the tangential feed of the cutting tool. On the basis, both the peripheral and the front cutting depths at each engagement point are derived as a function of cutting parameters using a cylindrical end mill. By dividing the cutting edges into a stack of disks and applying the linear-edge cutting force model to each disk, through coordinate transformation, numerical integration along the cutting edges and summation for the differential cutting forces of all the teeth, the overall instantaneous cutting forces acting on the whole cutting tool in the three orthogonal directions are obtained Based on the cutting force algorithm, the impact of cutting conditions such as the tangential and axial feedrates on the tangential, normal and axial cutting forces is investigated. Meanwhile, a set of cutting trials were conducted to validate the cutting force model. It is shown that the proposed model can well predicate the cutting forces in helical milling. Therefore, the proposed approach is proven to be a feasible and practical approach to determine cutting conditions in helical milling for shop floor applications.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.