<p>The tool nose radius (TNR) directly impacts the machined surface of Al/SiCp composites. To gain deeper insights into the milling process of Al/SiCp composites, this study establishes a milling force model that integrates the characteristics of the polycrystalline diamond (PCD) TNR and the effects of composite particles. It also examines the influence of TNR on surface roughness, machined surface quality, and subsurface integrity. Given the dynamic direction of cutting forces at any point on the tool nose cutting edge, the study decomposes the chip into incremental angular elements, defining the instantaneous chip thickness through angles. A milling force model for the TNR is proposed based on angular chip increments, and this model is combined with an axial micro-element model for linear edge cutting forces, forming a comprehensive PCD tool insert milling force model. Additionally, a tri-phase friction coefficient iterative model is introduced, considering the dynamic constitutive model based on particle effects and including particle damage, three-body abrasive rolling friction, two-body abrasive sliding friction, and matrix friction. Experimental validation confirms that the TNR significantly influences the milling force on Al/SiCp composites, with milling force increasing as the TNR grows. Different tool nose radii (TNRs) create distinct surface morphologies on Al/SiCp composites, where surface roughness initially rises and then decreases with increasing nose radius. Moreover, subsurface damage (SSD) depth increases with the TNR, showing a positive correlation with milling force.</p>