Metal additive manufacturing is a rapidly growing technique in industrial applications, with ongoing research aimed at improving the properties of materials produced through this method. For additive manufacturing to succeed, it must not only match the quality of traditional methods but also offer faster production. However, one significant challenge is that additively manufactured parts often fail to meet the surface finish requirements for various applications. This has led to renewed interest in subtractive manufacturing techniques, such as milling, to refine these parts. Combining additive and subtractive processes can help achieve tighter tolerances and better surface finishes. Machining remains essential in industries like aerospace and automotive, enabling the use of stronger materials and the creation of complex geometries with high precision. Key aspects of machining include predicting cutting and feed forces based on the feed rate and understanding machining-induced residual stresses. Additionally, modeling surface roughness is critical for improving the final product's quality. This study focuses on applying the Particle Finite Element Method (PFEM) to model milling in additively manufactured parts. The goal is to predict the finished surface characteristics, and the residual stresses left in the material after processing. Case studies are presented to highlight the effectiveness of this method, and the accuracy of the results is discussed. This approach demonstrates the potential of PFEM in optimizing the milling process for additive manufacturing, ensuring that the final parts meet both structural and surface quality requirements.