Experimental investigations and statistical modeling of cutting force and torque in rotary ultrasonic bone drilling of human cadaver bone

Abstract

Cutting force and torque are important factors in the success of the bone drilling process. In the recent past, many attempts have been made to reduce the cutting force and torque in the bone drilling process. In this work, drilling on human cadaver bones has been performed using rotary ultrasonic bone drilling process to investigate the effect of drilling parameters on cutting force and torque. The experimental work was carried on a recently developed rotary ultrasonic bone drilling machine for surgical operations. The experimental work was performed in two phases. The first phase includes a comparative study between rotary ultrasonic bone drilling and conventional surgical bone drilling, to study the influence of various drilling parameters (rotational speed, drill diameter, and drilling tool feed rate) on the cutting force and torque. The results revealed that the cutting force and torque produced during drilling operations in rotary ultrasonic bone drilling were lesser (30%–40%) than conventional surgical bone drilling. In the second phase, response surface methodology was used to perform the statistical modeling of cutting force and torque in rotary ultrasonic bone drilling process. Analysis of variance was performed at a confidence interval of 95% to analyze the significant contribution ( p < 0.05) of process parameters (drilling speed, feed rate, drill diameter, and abrasive particle size) on the responses (cutting force and torque). The confirmatory experiments were performed to validate the developed statistical models. It was found that both cutting force and torque decrease with increase in drilling speed and increases with the increasing drill diameter, feed rate, and abrasive particle size.

Effects of rotary ultrasonic bone drilling on cutting force and temperature in the human bones

“…Our newly designed machine performs on the principles of rotary ultrasonic machining (RUM). 39 Unlike the bulky CNC machine, this instrument is compact and easy to manipulate in the OT. It is enabled with three rotational and two linear movements to cover the large surface envelope.…”

“…A hollow drill tool (Figure 2(a)) and ultrasonic horn together formed the compound horn ( Figure 2), which magnifies the amplitude of ultrasonic vibration from 3 to 18-20 mm. The hollow tool was specially designed and manufactured to give a linear amplitude of 18-20 mm at the drilling end 39 and coated with diamond abrasive particles. It was 70 mm in length and 6.5 mm in the maximum shank diameter.…”

“…The preliminary study also showed similar findings. 39 The cutting force below 1000 r/min was too high and increasing the rotational speed above 3000 r/ min resulted in high temperature. Therefore, this study applied a minimum rotational speed of 1000 r/min and a maximum of 3000 r/min ( Table 2).…”

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review

“…4, 174 The principal cutting force (F z ) overlaps with the cutting velocity path and affects the drilling torque; a larger diameter increases principal cutting force and drilling torque. 164,174…”

“…For example, increasing drill bit diameter increases the chisel edge length, drill flute area, and web thickness. Many studies have reported an increase in drilling outputs-normal stress, 73 drilling force, 19,97,164,174,196 torque, 85,164,174 osteonecrosis regions, 6,7 and bone temperature 2,4,6, 16,42,43,51,59,70,81,85,91,97,98,101,105,115,123,130,159,176,180,181,199 -with the increase of drill diameter. Researchers have applied two-step drill bit (a drill bit with smaller drill tip for initial bone removal and larger shaft for drilling final hole diameter) and sequential drilling technique (increasing hole diameter sequentially until desired hole size is achieved) to reduce the thermal damage in bone.…”