Avaliação da retificabilidade de poliacetal com relação ao ferro fundido cinzento utilizando rebolo de carbeto de silício

Abstract

Polymers have a wide range of applications, from conventional plastics to advanced engineering materials. Among this group, polyacetal stands out due to its combination of durability, good mechanical resistance and faster production compared to steels, making it prominent for many industrial applications. It is widely used in the manufacture of engineering components such as gears, bearings, connectors, machine parts, and automotive components, among others. Among the machining processes, grinding provides a combination of narrow dimensional deviations and surface roughness below 1.6 µm, making it an alternative for processing polyacetal. However, the grinding process involves high specific energy when using conventional abrasive wheels, leading to a significant amount of heat being transferred to the workpiece during machining and resulting in thermal damage. When machining polymers, this problem become worse since their melting point is much lower than that of steels, and surface temperatures can cause deformations and other heat-related issues. This requires more attention in selecting cutting parameters to avoid damaging the workpiece. In this context, this study grinding process of polyacetal was carried out to determine appropriate cutting parameters. Three values of depth of cut (ae) were tested: 10, 30 and 45 µm, and two workspeed (Vw): 2.7 m/min and 7.5 m/min. Surface roughness parameters (Ra and Rz) and surface texture were analyzed through images of ground surfaces. Experimental trials were performed with cast iron for comparative purposes. The results showed that the roughness of polyacetal was reduced by up to 38% with as workspeed increased, unlike cast iron, which experienced an increase in roughness of up to 27%.