This paper represents a new lubricant method which is able to one-stroke drill deep holes with a length-to-diameter of 8, on the AISI SUS 304 stainless steel. By adding graphene nanosheet into typical soluble emulsion and then mixing with water, a nano fluid can be made. The results revealed that using nanofluid can provide a reduction of 4.4-fold of the drilling torque, and thus expand the tool life as many as 20 times, compared with using typical emulsion lubricant. The proper set of cutting parameters was found by using Taguchi L9 experiments as 550 rpm spindle speed and 0.05 mm/rev. The results can be expanded to apply in other deep drilling of hard-to-cut material, using inexpensive devices and avoiding peck-drilling. The proposed lubricant can also be promissing for other machining operations.

Implementing the ultrasonic vibration-assisted incremental sheet-forming (UISF) process has been proven to significantly reduce the forming force, improve the surface quality, and enhance the accuracy of the sheet-forming process. However, such effectiveness has primarily focused on easily deformable materials (such as AA1050 and AA1060 aluminum alloys) and small step-down sizes (from 0.3 mm to 0.5 mm). To further enhance the process, it is crucial to study larger step-down sizes and harder materials. In this study, a series of UISF experiments were conducted, with step-down sizes ranging from 0.5 mm to 1.5 mm and feed rates ranging from 200 mm/min to 1200 mm/min. The influence of ultrasonic vibration on the effectiveness of force reduction and the optimal operation parameters was experimentally tested. Forming aluminum alloy AA5052, a difficult-to-deform material with two thicknesses of 0.5 mm and 1.0 mm, indicates that the axial force Fz and the tool movement resistance force Fy tend to decrease significantly with ultrasonic vibration assistance. Optimal equations for force reduction Fz and Fy have been developed for plate thickness based on the step-down size and feed rate. The optimal results show that for 1.0 mm thickness, reductions in Fz and Fy can reach 58.73% and 69.17%, respectively, and that of 64.17% and 71.98%, respectively, for 0.5 mm thickness.

This study demonstrates a novel, low-cost lubrication technique that enables single-stroke deep hole drilling of SUS 304 stainless steel using a rotary twist drill with internal coolant channels. A graphene-based nanofluid, formulated by dispersing graphene nanosheets into a water-soluble emulsion and diluted with tap water, was internally delivered at low pressure (1.5 bar) and low flow rate (0.25 L/min). Comparative trials under varying cutting conditions (spindle speeds: 430–870 rev/min and feed rates: 0.04–0.10 mm/rev) revealed that drilling with the proposed nanofluid produced chips with favorable morphology and manageable length, facilitating efficient evacuation. In contrast, conventional emulsion generated crushed chips prone to clogging. The graphene-based nanofluid also significantly reduced the thrust force and extended the tool life, enabling stable deep-hole drilling without pecking or tool failure. Statistical analysis and Taguchi optimization confirmed the robustness of the proposed approach. Unlike high-pressure or ultrasonic-assisted systems, the proposed method offers a simple and energy-efficient solution for machining hard-to-cut materials under realistic manufacturing conditions.