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The micromachining process has been applied to the free form and micromolds markets. This has occurred due to the growth in demand for microcomponents. However, micromachining of hardened steels is a challenge due to the reduction in tool life and the increase of the surface roughness when compared with the macromachining process. This paper focused on the analysis of micromilling forces on hardened AISI H13 steel with different grain sizes. Experimental tests were carried out on workpieces with different austenitic grain sizes and a hardness of 46 HRC. Micro-end-mill cutters with a diameter of 0.5 mm and (TiAl)N coatings were applied in the milling of workpieces of 11 × 11 mm. The input parameters were two radial depths of cut, two cutting speeds, and two feed rates. The influence of the input parameters on the response cutting force was analyzed using the Taguchi method. Finally, considering the large grain size, the cutting forces in the x-, y-, and z-axes direction were small.

This work shows a study on the micro milling of Ti-6Al-4V Titanium alloy where the effect of tool wear on the surface finish of the machined part was analyzed. New and worn micro cutters were applied to produce grooves with 0.5 mm of width and 0.025 mm of heights. The surface roughness was measured in the Ra and Rz values and the results showed that the surface roughness was not influenced by the tool’s condition. However, when new tools were used the increase of cutting speed generated an improving of the surface roughness and the same effect occurred with the decrease of feed rate.