Measurements of viscosity of small volume samples are critical in analytical chemistry, hydrodynamics, micro-electromechanical systems. It is hard for the previous methods to measure the liquid with viscous large than 150 mPa.s. To enlarge the measurement range, a viscosity measurement method, in which the sample volume is less than 15 µL, was designed in this paper. In the proposed, the measure range is expanded to 750 mPa.s by the combination of flexible hinge and cantilever. In addition, to reduce the effects of surface tension, a multi-position method is adopted. The calibration results showed that the method performed well, and the uncertainty analysis indicated high accuracy. The effects of vessel width, density and temperature on the results are also investigated. The relative uncertainty of viscosity was estimated as 3 % indicating the validating of this method.

Titanium alloys (Ti-6Al-4V) are widely used in the aerospace field. However, as a typical difficult-to-machine material, titanium alloys have a low thermal conductivity, a high chemical activity, and a significant adiabatic shear effect. In conventional milling (CM), the temperature in the cutting zone rises sharply, leading to tool adhesion, rapid wear, and damage to the workpiece surface. This article systematically investigated the influence of process parameters on the surface roughness, cutting force, and cutting temperature in the ultrasonic-vibration-assisted milling (UAM) process of titanium alloys, based on which multi-objective optimization process of the milling process parameters was conducted, by utilizing the grey relational analysis method. An orthogonal experiment with four factors and four levels was conducted. The effects of various process parameters on the surface roughness, cutting force, and cutting temperature were systematically analyzed for both UAM and CM. The grey relational analysis method was employed to transform the optimization problem of multiple process target parameters into a single-objective grey relational degree optimization problem. The optimized parameter combination was as follows: an ultrasonic amplitude of 6 μm, a spindle speed of 6000 rpm, a cutting depth of 0.20 mm, and a feed rate of 200 mm/min. The experimental results indicated that the surface roughness Sa was 0.268 μm, the cutting temperature was 255.39 °C, the cutting force in the X direction (FX) was 5.2 N, the cutting force in the Y direction (FY) was 7.9 N, and the cutting force in the Z direction (FZ) was 6.4 N. The optimization scheme significantly improved the machining quality and reduced both the cutting forces and the cutting temperature.

Nickel-based superalloys, renowned for their exceptional high-temperature strength, oxidation resistance, and corrosion resistance, have become essential materials in the aerospace, defense, and nuclear industries. However, due to their poor machinability, common cutting processes often result in poor surface quality, difficulties in chip breaking, and significant tool wear. This study investigates the surface integrity of nickel-based superalloys during ultrasonic elliptical vibration cutting. The effects of various process parameters on the surface roughness, residual stress, and microhardness are systematically analyzed. The results indicate that under ultrasonic elliptical vibration cutting conditions, the surface roughness of the workpiece increases with the ultrasonic amplitude, cutting depth, and feed rate. It initially decreases and then increases with cutting speed, and decreases with an increase in the tool tip radius. The post-cutting residual stress in the nickel-based superalloy decreases with higher cutting speed and ultrasonic amplitude, but increases with greater cutting depth and tool tip radius. The surface microhardness increases with the cutting speed up to a point, after which it decreases, while it significantly increases with a higher ultrasonic amplitude, feed rate, and cutting depth. A comparative experiment was conducted between ultrasonic elliptical vibration and conventional cutting. The research results showed that when the cutting depth was 2 µm, the surface roughness and wear decreased by 19% and 53%, respectively, and the residual compressive stress and microhardness increased by 44% and 21%, respectively. This further verified the significant advantages of ultrasonic elliptical vibration cutting in optimizing machining performance.