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There is growing interest in multi-nozzle array printing, as it has the potential to increase productivity and produce more intricate products. However, a key challenge is ensuring consistent flow across each outlet. In the heat exchangers, achieving uniform distribution of flow in parallel channels is a classic goal. To address this issue in multi-nozzle array direct printing technology, high-viscosity slurry fluids can be utilized in place of water, and the structure of compact parallel channels can be employed. This study experimentally and numerically investigated the flow distribution law of Herschel-Bulkley fluids (high-viscosity slurry fluids) entering each manifold of the compact parallel channels, which contained a single circular inlet and multiple outlets. The research identified two types of factors that impact the non-uniformity flow coefficient (Φ), which reflects the uniformity of flow distribution in each channel of the structure: entrance and exit conditions (V, P1, P2) that have a negligible effect on Φ, and structural dimensions (D, S, L, N, A, d) that are the primary influence factors. By analyzing the experimental results, a prediction model was derived that could accurately calculate Φ (error < 0.05) based on three structural dimensions: A, S, and L. Through proper design of these structural dimensions, a consistent flow rate of each channel of the parallel channels can be ensured.

Traditional contact printing technology is primarily controlled by the shape of the mask to form the size, while for the more popular non-contact printing technologies, in recent years, adjusting the print parameters has become a direct way to control the result of the printing. High-viscosity conductive pastes are generally processed by screen printing, but this method has limited accuracy and wastes material. Direct-write printing is a more material-efficient method, but the printing of high-viscosity pastes has extrusion difficulties, which affects the printed line width. In this paper, we addressed these problems by studying the method of printing high-viscosity conductive paste with a self-made glass nozzle. Then, by parameter optimization, we achieved the minimum line width printing. The results showed that the substrate moving speed, the print height, and the feed pressure were the key factors affecting the line width and stability. The combination of the printing parameters of 0.6 MPa feed pressure, 200 mm/s substrate moving speed, and 150 μm print height can achieve a line width of approximately 30 μm. In addition, a mathematical model of the line width and parameters was established, and the prediction accuracy was within 5%. The results and the prediction model of the parameters provide an important reference for the printing of high-viscosity pastes, which have immense potential applications in electronics manufacturing and bioprinting.

The machining efficiency of hardened steel molds can be significantly improved through high-speed deep milling. However, under these circumstances, the temperature and milling force increase greatly, and the end mills are subjected to rapid wear. A feasibility study of the oil-on-water (OoW) method in the high-speed end milling of P20 hardened steel was conducted. The experimental results show that the tool life of OoW is significantly longer compared with that of dry cutting and compressed air cooling. Moreover, the OoW method promotes tool life under low- and high-speed milling conditions. Thermal wear phenomena (e.g., adhesion) are evidently suppressed, and the development of the milling force and tool wear is considerably slowed down in OoW processing. The main reason for the excellent cooling and lubrication performance of the OoW method is that a two-layer film (oil film + water film) is formed when the OoW droplets collide with the cutting interface. The evaporation of the water film removes much heat and prevents the high-temperature failure of the oil film. Moreover, the single use of oil mist and water mist leads only to a single-layer film, resulting in an evidently shorter tool life than that of the OoW method. In the OoW cutting process, the chipping belt of the flank face is discontinuous, and the wear of the adhesion/attrition is less severe compared with those of the other processing modes. In addition, the tool wear and chipping belt occur with a certain amount of material peeling, and the thermal fatigue and mechanical behavior of the tool substrate in a certain temperature range are the main reasons for the discontinuity of the chipping belt in the OoW process.

Hollow spherical corundum granules were introduced into a vitrified bond diamond grinding wheel as pore former. The influences of content and particle size of the hollow spherical corundum granules on porosity, flexural strength, and hardness of the vitrified bond diamond wheel samples were systematically investigated. The grinding performance of the designed vitrified bond diamond cup wheel on sapphire and 6H-silicon carbide (SiC) substrates was examined, and morphological properties of the ground surface were evaluated. Results showed that higher content and smaller size of hollow spherical corundum granules could lead to the increase of the porosity and the decrease of flexural strength and hardness. Sapphire and 6H-SiC substrates could be effectively ground by the vitrified bond diamond cup wheel containing 8% hollow spherical corundum granules. During the grinding, although a brittle mode dominated the material removal of two substrates, more ductile removals and lower surface roughness could be identified from 6H-SiC substrate than from sapphire.

The toolpath for a sharp corner is important in pocket machining during high-speed machining with numerical control. When milling a sharp corner, a longer tool engagement length generates larger engagement angle and milling force, which reduces the machining precision. To reduce the milling force at a sharp corner and clear up uncut materials, the toolpath at corners must be optimized. In this paper, a new method of generating the toolpath with circular cycle transition at a sharp corner is put forward to provide a new numerically controlled toolpath pattern for pocket milling. On the basis of a common contour-parallel toolpath, minimum radius arcs and circular cycles are added in sequence at a sharp corner. When the cutter comes to the sharp corner, the corner material is removed step by step with a sequence of circular cycles. The validity of the proposed method is confirmed through simulation and tests. The proposed toolpath method is realized by employing the Institute of Manufacturing Technology (IMT) computer-aided manufacturing (CAM) system. The toolpaths at sharp corners generated through commercial software and IMT-CAM software are tested by comparing the corresponding milling forces. It is illustrated in the results that the proposed method reduces the milling force effectively and is of great significance when it is applied in high-speed machining.