Abstract
BK7 glass is an important engineering material with extensive applications in high-quality and precision transmissive optical components. However, BK7 glass is considered to be a difficult-to-cut material due to its high brittleness and nonconductivity. This article presents the use of rotary ultrasonic machining process for drilling holes in BK7 glass. No previous reports have been found in the literature to experimentally investigate the response of the BK7 glass to rotary ultrasonic drilling. The experimental investigations take into account the effect of the key rotary ultrasonic machining input parameters including the ultrasonic power, spindle speed and feed rate on the output responses of cutting force, exit chipping, surface roughness, hole cylindricity and overcut errors, and surface integrity. The results show that the input parameters within the current ranges can significantly affect the quality of the drilled holes. Moreover, the selected level of any input parameter has the ability to significantly affect the influence of the other input parameters on the output responses. Through proper selection of input parameters, holes could be drilled in BK7 glass with less fractured topography, low surface roughness (1.32 µm), low exit chipping size (0.85), and very low cylindricity (3 µm) and overcut (73.6 µm) errors.
Highlights
BK7 glass is an important material extensively utilized in many high-quality optical applications such as lenses in various electronics
RUM is a hybrid machining process based on the combined material removal mechanisms of diamond grinding and ultrasonic machining resulting in higher material removal rates
The main aim of this study is to systematically present the effects of the main process parameters of rotary ultrasonic drilling including spindle speed, feed rate, and ultrasonic power on the key output responses such as axial cutting force, exit chipping size, surface roughness, and hole accuracy in terms of cylindricity and overcut errors while drilling BK7 glass
Summary
BK7 glass is an important material extensively utilized in many high-quality optical applications such as lenses in various electronics This is owing to the superior optical properties of BK7 glass, for instance, its high optical stability, optical transparency, and bubble-free property.[1] due to its brittleness, poor thermal and electrical conductivity, low fracture toughness, and high hardness, BK7 glass is a difficult-to-cut material and incurs high cost with traditional machining.[2] There is a key importance for identifying and developing the new machining processes capable of overcoming the challenging properties of difficult-to-cut materials for their effective utilization. The tools employed in RUM are through coolant to keep the tool cool and sweep away the debris during machining
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