Influence of Cutting Speed on Machining Force and Chip Morphology in Turning Self-lubricating Composites Sinterized

Currently, a constant concern in the industrial sectors is looking for an improvement in energy efficiency for machinery and equipment. In this context, due to the satisfactory mechanical properties and low coefficient of friction, sintered self-lubricating composites are a viable alternative to materials already used in engineering to contribute to a decrease in energy consumption and increase in sustainability. Hence, this work presents an analysis of the effect of varying cutting speed on the components of machining force and chip morphology in external longitudinal turning of a sintered self-lubricating composite. The specimens were manufactured by powder metallurgy process and have a metallic matrix, composed of iron powder with the addition of alloying elements (Ni and Si). hBN and graphite particles are used as solid lubricants. Six cutting speeds (v_c) were adopted, from 350 m/min to 850 m/min, with an increment of 100 m/min. The depth of cut and feed were set at 1.0 mm and 0.2 mm, respectively. The turning tests were carried out using carbide inserts, class P20, triangular shape with three cutting edges on a single face. During the machining tests, machining force were measured, and chip samples were collected. As a result, it was possible to observe a decrease in the components of the machining force with the increase of the cutting speed. Furthermore, when analyzing the chip morphology, the formation of segmented/arc chips was observed. As the cutting speed increases, the chips tend to present a reduction in their arc length, which modify the shape.