The Machining of Hard Mold Steel by Ultrasonic Assisted End Milling

Abstract

Abstract:This study describes the use of ultrasonic-assisted end milling to improve the quality of the machined surface of hard Stavax (modified AISI 420) mold steel and to reduce the amount of work involved in the final polishing process. The effects of input voltage, the stretch length and cutter holding force on the amplitude of the ultrasonic vibration used were measured. The effect of ultrasonic frequency (25 and 50 kHz) and amplitude (0, 2.20 and 3.68 µm) as well as the effect of the rake angle (6 • and −6 • ) and the cutter helix angle (25 • , 35 • and 45 • ) on tool wear and quality of the workpiece surface finish were also investigated. It was found that the ultrasonic amplitude increased with cutter stretch length and input voltage, as expected. The amplitude remained constant when the cutter holding force exceeded 15 N. The experimental results showed that the ultrasonic amplitude had an optimum value with respect to surface finish. However, large amplitude ultrasonics did not necessarily improve quality. Furthermore, the cutters used for ultrasonic-assisted milling show less wear than those used for normal milling. It was also found that a positive rake angle and cutters with a large helix angle gave a better surface finish.

Tailored Chip Breaker Development for Polycrystalline Diamond Inserts: FEM-Based Design and Validation

“…Three values of rake angle (α) were proposed: 10 • , 20 • and 30 • . It is assumed that higher rake angles lead to lower cutting forces, so the selection of a positive rake angles [38,39] is recommended. However, there are some drawbacks for excessive rake angles.…”

State-of-the-art review on vibration-assisted milling: principle, system design, and application

“…Ding et al [83] found that feed per tooth has a significant effect on the height of the top burr, and the use of vibration-assisted cutting in micro end milling could minimize the size effect and improve the cutting performance, thereby reducing the height of the top burr by 80%. Tsai et al [84] investigated the machining of hard mold steel by ultrasonic assisted end milling, and found that a positive rake angle and a large helix angle gave improved surface finish. Maurotto and Wickramarachchi [85] investigated the effects of frequency in ultrasonically assisted end milling on grain sizes of AISI 316L.…”

High-Speed Rotary Ultrasonic Elliptical Milling of Ti-6Al-4V Using High-Pressure Coolant

“…As an intermittent cutting method, ultrasonic vibration machining (UAM) has been widely discussed for its ability to open the tool-workpiece contact area intermittently. As one of the typical UAM processes, the ultrasonic-assisted milling technique has been widely applied to machine difficult-to-cut alloys for its superiority in expanding tool life, lowering cutting force and delivering better surface quality [18][19][20][21][22][23][24]. In order to obtain the intermittent cutting mode between the tool and the workpiece in UAM, its relative velocity in cutting direction should be controlled as the opposite to the tool rotation direction periodically.…”