This paper provides a comprehensive review on the dressing techniques of diamond grinding wheels. The common techniques with different tools were discussed in detail, which included the bonded SiC and diamond abrasive tools, loose abrasives, soft-elastic abrasive belts, and profiled diamond wheels. Meanwhile, laser dressing, electrical discharge dressing (EDD), and electrolytic in-process dressing (ELID) were also addressed. Some critical problems in the above dressing techniques were then analyzed and summarized for further investigation.

Rotary longitudinal–torsional coupled ultrasonic vibration-assisted grinding (LTUAG) is a new manufacturing method that can improve the grinding ability of silicon carbide ceramics. However, compared with longitudinal ultrasonic vibration-assisted grinding (LUAG), the role of torsional vibration in the grinding process is unclear. In this study, an effective method for measuring longitudinal–torsional coupled ultrasonic vibration amplitude and an experimental setup for measuring actual amplitude during grinding are proposed. The trajectory of the abrasive grains under the same grinding parameters and the same longitudinal amplitude during LTUAG and LUAG are analysed. Ultrasonic amplitude curves under the condition of tool rotation are then measured and analysed. Finally, the effect of torsional vibration on grinding force and surface roughness under the same grinding conditions is explained. Experimental analysis shows that the introduction of torsional vibration has little effect on the trajectory length and does not change the number of interference overlaps between abrasive grain tracks. Torsional vibration will only increase the cutting speed during grinding and reduce the undeformed chip thickness, which will reduce the grinding force and improve the surface roughness of LTUAG.

In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of the tool. In this case, centrifugal accelerations do not segregate the fluid between the evaporator and condenser. The experimental investigation is conducted to study the effects of centrifugal acceleration (0–738 m/s²), heat flux (9100–31,850 W/m²) and working fluids (methanol, acetone and water) on the thermal performance. Results show that the centrifugal acceleration has a positive influence on the thermal performance of the axial-rotating SLOHP when filled with acetone or methanol. As for water, with the increase of centrifugal acceleration, the heat transfer performance first increases and then decreases. The thermal performance enhances for higher heat flux rises for all the fluids. The flow inside the axial-rotating SLOHP is analyzed by a slow-motion visualization supported by the theoretical analysis. Based on the theoretical analysis, the rotation will increase the resistance for the vapor to penetrate through the liquid slugs to form an annular flow, which is verified by the visualization.

When grinding hard-to-machining materials such as titanium alloys, a massive grinding heat is generated and gathers in the grinding zone due to the low thermal conduction of the materials. The accumulated grinding heat easily leads to severe thermal damages to both the workpiece and the grinding wheel. A novel oscillating heat pipe (OHP) grinding wheel is one of the solutions to this phenomenon. The oscillating heat pipe grinding wheel can transfer the grinding heat directly from the grinding zone to avoid heat accumulation and a high temperature rise. In this paper, the temperature field of the grinding Ti-6Al-4V alloy is investigated, via the oscillating heat pipe grinding wheel, by numerical analysis. The three-dimensional thermal conduction model is built accordingly, containing the grinding wheel, grinding zone and Ti-6Al-4V workpiece. Due to the enhanced heat transport capacity of the oscillating heat pipe grinding wheel, the highest temperature in the grinding zone and the temperature on the ground surface of the workpiece decrease dramatically. For example, under a grinding heat flux of 1 × 10⁷ W/m², when using the grinding wheel without OHP and with OHPs, the highest temperature in the grinding zone drops from 917 °C to 285 °C by 68.7%, and the ground surface temperature decreases from 823 °C to 244 °C by 71.2%. Moreover, the temperature distribution on the grinding wheel is more uniform with an increase of the number of oscillating heat pipes.