Adjusting machined surface integrity of aluminum–silicon alloy through step-by-step feed cutting and multi-step finish cutting method.

Fatigue performance is largely dependent on the machined surface integrity of engineering parts. In this paper, effect of cutting steps and directions on machined surface integrity of aluminum–silicon alloy is investigated. Machining induced surface quality under the forward and reverse finish cutting as well as the step-by-step feed cutting method is contrastively analyzed. The results indicate that the final machined surface integrity can be controlled through adjusting the finish cutting steps, and governing finish cutting directions can also be effective when the finish cutting step is fixed. High-machined surface integrity can be obtained when it adopts reverse finishing in first-step while it employs forward finishing in second-step, where there are little micro-defects on the machined surface, relatively low degree of surface hardening and surface residual stress, along with smaller surface roughness, respectively. Moreover, step-by-step feed cutting method can effectively break chips, avoid surface scratching, chips softening, and forming the built-up edge. It can also reduce the degree of elastic–plastic recovery and thermal expansion on the machined surface, improve surface hardness, and obtain surface compressive residual stress. There are many micro-defects on machined surface by single-step feed cutting. However, when the step-by-step feed cutting method is adopted, the forward finishing surface emerges almost no micro-defects, but that of reverse finishing exhibits severe grain breakage. The proposed adjusting method in cutting steps and forward-reverse cutting directions may be of interest to the engineering practice, and will help improving the machined surface quality and fatigue life of aluminum–silicon alloy engineering parts. [ABSTRACT FROM AUTHOR]