Fabrication of Various Dimple Shapes and Arrays on a Hypereutectic Al-Si Alloy Using a Turning Process

A hypereutectic Al-Si alloy piston has great potential for use in the automotive industry, especially for engine components, due to its lightweight, excellent castability, good thermal conductivity, high strength and excellent corrosion resistance. The silicon content in the A390 is between 17-18%. This article presents various shapes of dimples that can be fabricated on a cylindrical shape part of A390 using the turning process with aid of dynamic assisted tooling (DATT). To minimize the number of the experiment, the Taguchi method, with an L8 orthogonal array, was used to accommodate two different sets of seven parameters used in the fabrication of dimpled structures, i.e. cutting speed of 2-9 m/min, feed rate of 0.4-0.6 mm/rev, DOC of 0.05-0.01 mm, frequency of 15-28 Hertz, the amplitude of 1-3 mm, using two different cutting tool i) rake angle of +4o and -8.5o, relief angle of 4o and 7o, and nose radius of 0.4 and 0.8 mm, ii) Rake angle of +9° and -20°, and relief angle of +7° and +17°, and nose radius 8 mm. By using these turning parameters, 3 dimple shapes were produced; spherical, short drop and long drop shapes, with almost square and hexagonal arrays.