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Prediction and control of machining distortion is a primary concern when manufacturing monolithic components due to the high scrap and rework costs involved. Bulk residual stresses, which vary from blank to blank, are a major factor of machining distortion. Thus, a bulk stress characterization is essential to reduce manufacturing costs linked to machining distortion. This paper proposes a method for bulk stress characterization on aluminium machining blanks, suitable for industrial application given its low requirements on equipment, labour expertise, and computation time. The method couples the effects of bulk residual stresses, machining stresses resulting from cutting loads on the surface and raw geometry of the blanks, and presents no size limitations. Experimental results confirm the capability of the proposed method to measure bulk residual stresses effectively and its practicality for industrial implementation.

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This article presents experimental studies on micromilling thin walls to explore process capabilities in direct manufacturing of high aspect ratio features using tungsten carbide micro-end milling tools for two different materials: aluminium and brass. This study has been conducted in two phases. At first, the effects of micromilling parameters on the surface roughness have been investigated and most suitable machining conditions in obtaining highest surface quality have been identified. In the second phase, the effects of machining strategies have been explored in order to optimize final quality of the thin walls in terms of straightness of the machined thin walls, uniformity of wall thickness and burr presence. As a result of this experimental study, optimized machining parameters and strategies are presented. In the case of micromilling brass (CuZn36Pb3), a down-milling cutting direction with a Z-step milling strategy at a spindle speed of 35,000 r min−1, an axial depth of cut of 150 µm and a feed rate of 150 mm min−1 provided the best overall thin-wall quality. In the case of micromilling aluminium (Al6061-T4), a down-milling cutting direction with a ramp milling strategy, a spindle speed of 25,000 r min−1, an axial depth of cut of 150 µm and a feed rate of 200 mm min−1 yielded the best results.

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