Machining Performance Analysis of Rotary Ultrasonic-Assisted Drilling of SiC_f/SiC Composites

Abstract

An SiCf/SiC composite has the following excellent properties: high strength, low specific gravity, and high temperature resistance, which has great prospects in the combustion chamber of rockets or aero engines. Hole-making in SiCf/SiC parts is an important processing method. Generally, water-based or oil-based coolants are avoided, so dry drilling is the primary hole-making approach for SiCf/SiC. However, the abrasion resistance and high hardness of SiCf/SiC often lead to fast tool wear as well as serious damage to the fiber and matrix during dry drilling. This study proposes an innovative strategy for hole-making in SiCf/SiC parts—rotary ultrasonic-assisted drilling (RUAD) using an orderly arranged brazed diamond core drill. The influence of tool life and wear on drilling accuracy is analyzed. Additionally, the impacts of the process parameters of conventional drilling (CD) and RUAD on drilling force, torque, the surface roughness of the hole wall, and the exit tearing factor are investigated. The results show that the orderly arranged brazed diamond core drill exhibits longer tool life and higher accuracy in hole-making. Meanwhile, compared with CD, RUAD with the proposed core drill effectively improves the drilling quality and efficiency, and reduces the force and torque of drilling. The range of process parameters for dry drilling is broadened.

Keywords

• SiC_f/SiC
• rotary ultrasonic-assisted drilling
• diamond
• core-drill
• lifetime