Study On Abrasive Flow Machining Performance Of Typical Additive Manufacturing Parts

With the development of science and modern manufacturing technology,there is an increasing demand for complex parts,which are widely used in aerospace,biomedical and transportation fields.However,some traditional processing methods are slightly difficult to produce these complex parts.Additive manufacturing technology can effectively solve the problem of forming parts with complex structures.However,due to the forming characteristics of additive manufacturing technology,the parts usually have defects such as "powder adhesion" and "balling effect",which seriously affect the service performance and life of the parts.Therefore,it is necessary to carry out subsequent processing work for additive manufacturing parts.In order to solve the problem of poor processing accessibility and fatigue performance of additively manufacturing parts,this paper takes two typical parts as examples to explore the improvement of surface quality and fatigue performance of additively manufacturing parts by abrasive flow machining.Introducing principle of abrasive flow machining,the types of common abrasive particles and the characteristics of non-Newtonian fluids are summarized.In addition,the conditions satisfied by abrasive media in processing are expounded in combination with empirical formulas.Next,the difference is compared in the removal process by AFM between parts formed by additive manufacturing and made by other traditional method.Based on the above analysis,the removal process and results are described in detail for additive manufacturing parts by AFM.Aiming at the inner surface of special shaped tube made by selective laser melting(SLM),the accessibility test of abrasive flow machining is carried out by designing the fixture and selecting the appropriate abrasive media.The distribution of velocity and pressure of abrasive media is simulated by Polyflow in ANSYS19.2.After AFM,the roughness Ra of the internal surface of the special-shaped tube decreases from 10?m to 1?m.In addition,the uniformity of material removal is studied with Peston equation.Aiming at the spindle-shaped fatigue part made by SLM,the influence is studied on the fatigue performance of AM parts by AFM.The effect is analyzed on abrasive media mass fraction,abrasive particle size,processing pressure and other parameters for the surface quality of AM parts.Experiment results have shown that the material removal of AM parts is better with higher pressure,high mass fraction,and large-diameter abrasive particles.The initial surface roughness Ra can be reduced from 15?m to 0.2?m.Then,fatigue tests are performed on the pindle-shaped fatigue part before and after AFM processing.The experiment results show that the number of fatigue testing cycles of workpiece is increased from the initial 7880 times to 14475 times after AFM processing.By observing the fatigue fracture,it is found that the fatigue source of initial part originates from the subsurface of the workpiece,and the fatigue fracture is rough;after the abrasive flow machining,the fatigue crack originates from the inside of the part,and the fatigue fracture is relatively flat.Based on the research of abrasive flow machining,this paper further explores the influence of AFM on the fatigue performance of additive manufacturing parts,and studies the machining accessibility of complex parts with micro inner flow channels,which is of great significance to improve the comprehensive performance of additive manufacturing parts.