Improved Process Control and Model of Axial Forces of One-way Abrasive Flow Machining

Abrasive flow machining (AFM) is an abrasive machining process used to machine internal geometries like bores in terms of deburring and finishing the surface with high performance. A silicate-based medium is forced through the internal geometry of a work piece by a hydraulic cylinder. The medium contains a certain amount of abrasive particles like carbide or diamond which influence the removal rate and surface quality. For example, components of fuel injection systems are treated with the process in order to withstand higher internal pressures. One goal is the improvement of the surface quality whereas the other one is the reduction of stress concentrations at bore intersections due to the abrasive deburring and defined rounding. In this paper, an optimized process control is proposed by combining different levels of piston pressure in one machining procedure. This can be compared to roughing and finishing in conventional machining and is supposed to reduce the lead time while achieving the lowest possible surface roughness. A commonly used automotive steel AISI 4140 was used for the investigation. Additionally, a force model based on in-process measurements of axial forces will be developed. The force model focuses on the influence of the applied piston pressure on the friction conditions of the AFM medium.