A comparative machinability analysis of aged and freshly manufactured epoxy resins through orthogonal machining experiments

Abstract

Applications of thermoset epoxy resins in load-bearing fibre-reinforced polymer (FRP) composites are decisive, mainly due to their excellent material properties, low viscosity before hardening and good adhesion with the reinforcing fibres. Although numerous experiences on the machinability of FRPs have been published, these experiences can be only indirectly adapted to pure epoxy resins. Reflecting on the lack of knowledge on the machinability of epoxy resins, the main aim of the present study is to compare the machinability of aged and freshly manufactured epoxy resins. Half of the epoxy specimens were naturally aged in a continental climate environment for a year, while the other half was manufactured prior to the orthogonal machining experiments. The experiments were conducted in a dry condition in a Kondia B640 machining centre. The cutting speed and the uncut chip thickness were varied systematically. The cutting force was measured by a KISTLER 9257B dynamometer, and the machined surfaces were characterised by a Mitutoyo SJ400 surface tester and a Keyence VR-5000 3D profilometer. The experimental results prove that the aged epoxy degraded significantly; thus, the specific cutting force is significantly smaller than that of freshly manufactured epoxy. However, the surface quality was not significantly influenced by the polymer degradation.