A main requirement in the field of polymer composites milling with fibre reinforcement is to machine with high quality in one operation (without delamination or burrs). That requires precise selection of cutting tool geometry and cutting conditions. Fibre-reinforced plastics (FRPs) are difficult-to-machine materials due to high abrasivity, relatively low melting point of polymeric matrices and inclination to delamination or large burr formation. This study investigates the main factors influencing the forces, temperature and surface quality in terms of the cutting conditions through ANOVA testing. Machining during this experiment was performed with a polycrystalline diamond (PCD) end mill. Next, the strongest factor with various double-helix cutting tool geometry was compared. The geometric model of the cutting forces was created based on previous measurements as well as a general empirical model of cutting forces, temperature on the machined surface and average delamination length for C/PPS material.

The importance of the 3D metal printing parts still increases in many branches of production not only for prototyping. The metal prints need machining very often to obtain specific shape, accurate dimensions as well as superior surface roughness. Internal structure of 3D metal prints differs from...

This study investigated the influence of cryogenic cooling on chip formation and morphology during the turning of aluminum–silicon carbide (A359/SiC-20wt%) composites using an uncoated tungsten carbide cutting tool. The primary objective was to enhance the cutting conditions and improve the overall efficacy of the machining process for aluminum composite materials. Compared with dry machining, cryogenic cooling significantly altered the chip formation process, producing shorter and less curled chips at all tested cutting speeds. The rake and dual cooling strategies proved to be the most effective in terms of chip breakability, despite the relatively unchanged tool-chip contact length (chip ratio increased up to 25% and chip curl increased up to 20%). Cryogenic cooling also led to a reduction in average chip thickness, particularly with the dual cooling strategy, contributing to improved material removal efficiency. Microstructural analysis revealed that under cryo-cooling conditions, the hard SiC particles were distributed more uniformly within the chips, in contrast to the particle redistribution along the shear bands observed in dry cutting. Chip separation is primarily facilitated by the formation and propagation of cracks and microcracks along the matrix-particle interface, leading to noticeably frayed chip edges and improved breakability. The study also examined the effects of cutting speed and cooling strategy on chip characteristics, such as chip curl diameter, average chip thickness, chip compression ratio, and shear angle. For example, the chip curl diameter decreased by 18% with cutting speed and the shear angle increased by 16%. These findings contribute to the understanding of machining aluminum matrix composites under cryogenic conditions and provide insights for optimizing cutting parameters to enhance the machining performance, tool life, and surface quality.

This article focuses on the development of a mathematical model of a cutting force that is applicable for coated and uncoated cutting tool inserts and aims to enable more accurate calculation of the cutting force. Two common PVD coatings, AlTiN and TiAlCrN, were used. Firstly, a mathematical model of the cutting force based on the specific cutting force and cutting area is proposed. This mathematical model considers the cutting speed and coating correction factor as well as the real cutting edge geometry, i.e., it includes both the straight and rounded parts of the cutting edge. For this proposed model, material constants for C45 steel, which was machined with uncoated inserts, were obtained. Before determining an equation for a coating correction factor and implementing it into the model, experimental cutting force data for coated and uncoated inserts were compared using a paired t-test. The result was that the difference between them was statistically significant. Their percentage difference was found to be up to 4%. The correction factor equation that was obtained and implemented into the mathematical model was applied to compare the calculated and experimental data of the coated inserts, also using a paired t-test. The result was that the difference between them was insignificant. Moreover, their percentage difference was found to be up to 0.6%.