Ultrasonic-assisted Drilling Research Articles

Delamination assessment and prediction in ultrasonic-assisted drilling of laminated hybrid composites

This study presents a novel application of the Random Forest (RF) algorithm to predict delamination in ultrasonic-assisted drilling (UAD) of carbon fiber reinforced polymers (CFRPs). It performs a multi-dimensional analysis of factors including graphene nanoplatelet (GNP) addition, ultrasonic vibration, cutting tool type, and feed rate on delamination damage. The RF algorithm was chosen for its ability to handle both regression and categorical tasks. The model demonstrated strong predictive performance, achieving an R² value of 0.9445 on test data, with a root mean squared error (RMSE) of 0.32% and a mean absolute error (MAE) of 0.29% relative to the average values. Analysis of variance (ANOVA), Sobol sensitivity, and Shapley additive explanations (SHAP) analysis were used to assess the impact of input parameters. Sobol identified the cutting tool type and feed rate as the most influential factors, contributing 37.7% and 34.3% to delamination variance, aligning with ANOVA findings. SHAP further confirmed the tooling type and feed rate as key factors, with contributions of 48.75% and 32.61%. The analyses revealed that GNPs increased delamination due to higher thrust forces, while ultrasonic vibration and high-cobalt tools reduced delamination. Optimal conditions were a feed rate of 0.08 mm/rev with an 8% cobalt tool and ultrasonic vibration, excluding GNPs.

Investigation of ultrasonic-assisted drilling temperature of SiCp/Al composites

ABSTRACT Due to their excellent properties and low manufacturing costs, SiC particle-reinforced Al matrix composites (SiCp/Al) find extensive application in automobile manufacturing and aerospace. However, SiCp/Al is less machinable. The ultrasonic-assisted drilling (UAD) decreases tool wear and enhances the quality of drilled holes when compared to conventional machining techniques. This paper investigates the effect of drilling temperature variations induced by processing conditions on the degree of softening of the base material during UAD of SiCp/Al. It also analyses the mechanism of how drilling temperature affects the quality of the holes made from the perspective of matrix softening. The study demonstrates a regularity in the impact of spindle speed, ultrasonic supply voltage(ultrasonic vibration amplitude), and feed rate as a function of drilling temperature. The effects of temperature changes caused by each of these factors on import/export edge defects, surface scratches on the hole wall, and tool machinability vary.

Cryogenic and ultrasonic-assisted micro-drilling of printed circuit boards using high-frequency-amplitude spindle

Printed circuit boards (PCBs) are key components in computers, 5G, 6G, and other wireless communication devices. On the other hand, the manufacture of micro-holes in PCBs faces severe challenges. Conventional micro-drilling methods often encounter challenges such as poor surface quality and limited tool life. To overcome these issues, a novel micro-drilling method called cryogenic and ultrasonic-assisted micro-drilling (CUAMD) has been developed. This study compared four drilling methods to investigate the benefits of cryogenic and ultrasonic-assisted drilling in hybrid machining processes: conventional micro-drilling (CMD), cryogenic-assisted micro-drilling (CAMD), ultrasonic-assisted micro-drilling (UAMD), and cryogenic and ultrasonic-assisted micro-drilling (CUAMD). The experimental results unequivocally indicate that the utilization of cryogenic-assisted drilling leads to a significant reduction in cutting heat during the machining process. This not only contributes to an improvement in machining accuracy but also exerts a positive influence on tool life and surface morphology. Ultrasonic-assisted drilling separates chips into smaller volumes through high-frequency-vibration, effectively reducing the cutting forces. The high frequency of 38.25 kHz and high amplitude vibration of 5.16 μm of the ultrasonic spindle induced vibrations on the drill bit. Liquid nitrogen with a pressure and temperature of 28 kPa and − 196 °C, respectively, was used in the cryogenic-assisted method. The superior machining performance of the CUAMD approach was evaluated by comparing it to various methods, including cutting forces, tool flank wear, entrance/exit hole morphology, and chip formation. The CUAMD method avoids chip entanglement, suppresses burrs, and reduces the maximum cutting force, maximum torque, and exit hole damage factor Fd by 47.7 %, 56.1 %, and 42.5 %, respectively, compared with CMD.

Influence of cutting tool design on ultrasonic-assisted drilling of fiber metal laminates

Ultrasonic-assisted drilling (UAD) is a machining process that is known to improve the hole quality and reduce cutting forces. Previous studies focused on optimizing cutting parameters to improve the hole quality in conventional drilling (CD) and UAD, as well as to finding the optimum vibration parameters (frequency and amplitude) that will increase the effectiveness of the UAD process. However, the influence of cutting tool type during UAD has been largely overlooked. This research aims to address this gap by analyzing the effect of cutting tool type during UAD on the cutting forces and hole quality in GLARE (Glass Laminate Aluminum-Reinforced Epoxy) laminates. Four types of drills, namely, twist drill (TD), double cone drill (DCD), a step drill type 1 (SD1), and step drill type 2 (SD2) with different step length, were selected for this study. The lowest thrust force (47.04 N) and torque (0.079 Nm) were achieved using twist drill, while DCD, SD1, and SD2 exhibited higher thrust forces (12.81%, 20.69%, 41.3%) and torques (94%, 92%, 91%), respectively. In addition, TD produced high-quality holes with lowest surface roughness (Ra 1.66 μm, Rz 10.58 μm) and minimal burr formation (entry burr height 152.3 μm, exit burr height 69.22 μm). Conversely, DCD, SD1, and SD2 showed higher surface roughness Ra (23%, 16%, 24%) and Rz (16%, 37%, 29%), respectively, compared to the TD. Holes drilled using SD1 and SD2 generally had smaller burr height. Overall, UAD system effectively reduced cutting forces at low spindle speed and feed rate. To achieve higher drilling quality, specifically to reduce the surface roughness and exit burr height, a medium spindle speed of 3000 rpm, a feed rate of 225 mm/min is recommended. Drilling at higher cutting parameters using UAD resulted in a decline in hole quality, except for entry burr height.

High-efficiency ultrasonic assisted drilling of CFRP/Ti stacks under non-separation type and dry conditions

High-efficiency ultrasonic assisted drilling of CFRP/Ti stacks under non-separation type and dry conditions

Ultrasonic-assisted drilling of cortical and cancellous bone in a comparative point of view

BackgroundDuring bone drilling, a common procedure in clinical surgeries, excessive heat generation and drilling force can cause damage to bone tissue, potentially leading to failure of implants and fixation screws or delayed healing. With this in mind, the aim of this study was to evaluate the efficiency of ultrasonic-assisted drilling compared to conventional drilling as a potential method for bone drilling. MethodsThis study examined optimal drilling parameters based on previous findings and investigated both cortical and cancellous bone. In addition to evaluating drilling force and temperature elevation, the effects of these factors on osteonecrosis and micro-crack formation were explored in ultrasonic-assisted and conventional drilling through histopathological assessment and microscopic imaging. To this end, three drilling speeds and two drilling feed-rates were considered as variables in the in vitro experiments. Furthermore, numerical modeling provided insight into temperature distribution during the drilling process in both methods and compared three different vibration amplitudes. ResultsAlthough temperature elevations were lower in the conventional drilling, ultrasonic-assisted drilling produced less drilling force. Additionally, the latter method resulted in smaller osteonecrosis regions and did not produce micro-cracks in cortical bone or structural damage in cancellous bone. ConclusionsUltrasonic-assisted drilling, which caused less damage to bone tissue in both cortical and cancellous bone, was comparatively more advantageous. Notably, this study demonstrated that to determine the superiority of one method over the other, we cannot rely solely on temperature variation results. Instead, we must consider the cumulative effect of both temperature elevation and drilling force.

Influence of Machining Condition and Nano-Graphene Incorporation on Drilling Load and Hole Quality in Both Conventional Drilling and Ultrasonic-Assisted Drilling of CFRP

Influence of Machining Condition and Nano-Graphene Incorporation on Drilling Load and Hole Quality in Both Conventional Drilling and Ultrasonic-Assisted Drilling of CFRP

Experiment analysis on defects in ultrasonic-assisted drilling of carbon fiber reinforced plastic with different diameter drills

Carbon fiber reinforced polymers (CFRP) are increasingly used in aerospace, military, and automotive applications due to their high specific strength and corrosion resistance. CFRP components usually require small-hole machining before assembly. CFRP parts are susceptible to defects such as tears and uncut fibers during hole machining. Ultrasonic-assisted drilling (UAD) contributes to the suppression of their defects. However, preliminary experiments revealed that the effect at different diameters is not the same. Therefore, this paper innovatively compares the effect of ultrasonic-assisted machining on the suppression of defects under different hole diameters and investigates the mechanism. The effects of machining parameters such as ultrasonic power, feed rate, and rotational speed on burr and tear defects of holes under different hole diameters are experimentally studied and theoretically analyzed. It was shown that the lowest defective machined holes were obtained at 50% (4 μm) ultrasonic power for all hole diameters, while higher ultrasonic power would result in an increase in machining defects. Compared with small hole diameters, there are relatively fewer uncut fibers at large hole diameters, but the tearing defects are more severe. The defect suppression effect of ultrasound is more pronounced at larger holes. The change in cutting force due to ultrasound is an important reason for the difference in machining defects. At a diameter of 6 mm, the longitudinal cutting force decreased by 58.7%, while uncut fibers and tearing defects decreased by 45.1% and 12.6%, respectively. This study can provide a theoretical basis for the selection of ultrasonic power and other parameters when machining holes of different diameters.

Burr constitution analysis in ultrasonic-assisted drilling of CFRP/nano-graphene via experimental and data-driven methodologies

In this study, a comprehensive investigation was undertaken to analyze the impact of various factors on thrust force and burr damage in carbon fiber reinforced polymer laminates during drilling operations. The factors examined included the incorporation of nano-graphene, the application of ultrasonic vibration, the type of cutting tool, and the feed rate. Statistical and machine learning techniques were employed to analyze the data, and image processing was utilized to illustrate the extent of burr damage surrounding the drilled holes. The developed model exhibited satisfactory prediction accuracy with minimal error rates. Statistical analysis revealed that the feed rate exerted the greatest influence on thrust force and facilitated the burr generation. Likewise, the addition of nano-graphene resulted in an increased thrust force due to improved rupture limits, consequently leading to cleaner holes with minimal burr damage. Furthermore, the implementation of ultrasonic vibration and the use of high-cobalt cutting tools were found to enhance drilling performance by reducing thrust force and minimizing the burr formation. The best hole quality was achieved at the lowest feed rate, in combination with a cutting tool containing 8% cobalt and the utilization of ultrasonic vibration.

A study on the ultrasonic vibration on the cutting performance during ultrasonic-assisted drilling of CFRP with twist and dagger drill bits

During the drilling process of carbon fiber reinforced polymer (CFRP), defects such as exit delamination, tearing, and burrs are prone to occur, among which excessive axial force during drilling is the main reason for the generation of exit delamination defects. In this study, ultrasonic-assisted and conventional drilling with twist and dagger drills were investigated on 5 mm-thick multi-directional laminated fiber sheets made of T300-12k/AG80 carbon fiber composite with different orientations. The axial force evolutions in each case were monitored when drilling holes in CFRP plates, and the axial force of drilling and the appearance characteristics of hole outlet were compared. The experimental results showed that the ultrasonic assisted drilling reduced the axial drilling forces of twist and dagger drill by up to 20.6% and 30.7%, respectively, compared to conventional drills. In addition, as the feed rate increases, the axial force of drilling gradually increases, and the exit delamination factor shows an overall increasing trend. The ultrasonic vibrations reduced the exit delamination damage of both drills. A special structure of the dagger drill effectively avoided exit delamination during ultrasonic-assisted drilling, which makes the incision more neat to improve the processing quality.

Multiscale modelling and experimental analysis of ultrasonic-assisted drilling of GLARE fibre metal laminates

This study aims to evaluate the effectiveness of Ultrasonic-assisted drilling (UAD) of Glass laminate aluminium reinforced epoxy (GLARE) at high cutting speeds (Spindle speeds: 3000–7500 rpm; feed rates 300–750 mm/min) by analysing the thrust force and hole quality metrics (surface roughness, hole size, and burr formations. The research also presents numerical modelling of FMLs under conventional and UAD regimes to predict thrust force using ABAQUS/SIMULIA. The thrust force and exit burrs were reduced by up to 40.83 % and 80 %, respectively. The surface roughness metrics (Ra and Rz) were slightly higher using UAD but remained within the desirable limits of surface roughness for machined aeronautical structures. The discrepancy between the simulation and experimental results was adequate and did not exceed 15 %. The current study shows that it is feasible to drill holes in GLARE using higher cutting parameters and maintain excellent hole quality, which means increased productivity and reduced costs.

Ultrasonic assisted pecking drilling process for CFRP/Ti laminated materials

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) laminated materials are widely used in aerospace and marine industries because of their excellent physical and electrochemical properties. The extensive demand requires a higher level of hole making technology to reduce the material damage caused by hole making. In this paper, we adopt a novel machining method, which combines Ultrasonic Assisted Drilling (UAD) and pecking drilling to generate a new machining method, Ultrasonic Pecking Drilling (UPD). Based on this, this study compares Conventional Drilling (CD), UAD and UPD in terms of thrust using orthogonal test method. In this paper, CFRP exiting delamination damage is investigated for three processing methods, and indirect measurement of interface temperature as well as detection of CFRP entrance delamination damage are carried out for UPD process. In addition, the tool wear and the exit burr of titanium alloy are analyzed for the three processes under different parameters. The test results show that UPD performed better in terms of thrust, the lowest thrust force is reduced by 35.1 % and 14.8 % at low feeds, respectively. CFRP exit delamination and tool wear are also good compared to both CD and UAD. Compared to CD, the maximum delamination damage decreased by 6.37 %. Besides, UPD results in better hole surface quality, where the roughness can be reduced by up to about 40 %. The obtained results show that UPD is a worthwhile option for drilling CFRP/Ti laminated materials.

An experimental study on ultrasonic-assisted drilling of Inconel 718 under different cooling/lubrication conditions

An experimental study on ultrasonic-assisted drilling of Inconel 718 under different cooling/lubrication conditions

Comparative study on machining performance of conventional and ultrasonic-assisted drilling of carbon fiber-reinforced polyetheretherketone composite

Comparative study on machining performance of conventional and ultrasonic-assisted drilling of carbon fiber-reinforced polyetheretherketone composite

Leveraging ultrasonic actuation during inclined orthopaedic bone drilling: An experimental and histological study

The treatment of fractured bones imperatively requires an orthopaedic bone drilling procedure. During the drilling of fracture bone, induced cutting force and temperature elevation may affect the initial stability and pullout strength at the bone-screw interface. Rotary ultrasonic-assisted drilling is gaining high attention to promote initial holding strength by reducing thermal energy and induced cutting force. Therefore, the proposed work is focused to leverage ultrasonic actuation to elevate the pullout strength by mitigating induced cutting force and temperature rise at the drill site. The technique of ultrasonic-assisted drilling is compared with conventional drilling of porcine femur bones. The influence of different drilling parameters such as insertion angle, feedrate, rotational speed and ultrasonic amplitude was monitored on the output characteristics. The infrared thermal imaging technique and force dynamometer was used to monitor temperature elevations and induced force. An increase in induced cutting force was observed to surge thermal energy and microcracks that lead to temperature elevations. Moreover, higher temperature and cutting force resulting lower biomechanical pullout strength of orthopaedic bone screws. In order to evaluate the effects of heat generation on tissue damage, osteonecrosis and bone morphology, histopathological analysis was performed at the drilled sites. It was witnessed that ultrasonic-assisted drilling was associated with higher viable lacunes and filled osteocytes leading to greater cell viability compared to conventional drilling. The present work shed light on an ultrasonic-assisted drilling system that is essential for low-trauma surgeries for orthopaedic applications.

Combined use of ultrasonic-assisted drilling and minimum quantity lubrication for drilling of NiTi shape memory alloy

The drilling of shape-memory alloys based on nickel-titanium (Nitinol) is challenging due to their unique properties, such as high strength, high hardness and strong work hardening, which results in excessive tool wear and damage to the material. In this study, an attempt has been made to characterize the drillability of Nitinol by investigating the process/cooling interaction. Four different combinations of process/cooling have been studied as conventional drilling with flood cooling (CD-Wet) and with minimum quantity lubrication (CD-MQL), ultrasonic-assisted drilling with flood cooling (UAD-Wet) and with MQL (UAD-MQL). The drill bit wear, drilling forces, chip morphology and drilled hole quality are used as the performance measures. The results show that UAD conditions result in lower feed forces than CD conditions, with a 31.2% reduction in wet and a 15.3% reduction in MQL on average. The lowest feed forces are observed in UAD-Wet conditions due to better coolant penetration in the cutting zone. The UAD-Wet yielded the lowest tool wear, while CD-MQL exhibited the most severe. UAD demonstrated a ∼50% lower tool wear in the wet condition than CD and a 38.7% in the MQL condition. UAD is shown to outperform the CD process in terms of drilled-hole accuracy.

Research on chip mechanism of Inconel 718 with ultrasonic assisted drilling by step drill

Research on chip mechanism of Inconel 718 with ultrasonic assisted drilling by step drill

Simulation and experimental investigations of ultrasonic-assisted drilling with Micro-PDC bit

Ultrasonic-assisted drilling (UAD) technology is a new drilling technology, which combines polycrystalline diamond compact (PDC) bits and performs better than conventional PDC drilling in improving the rock-breaking efficiency during deep hard formations. In this study, a series of simulations and laboratory tests were conducted to explore the dynamic rock-breaking mechanism of UAD with a PDC bit and the influence of different input parameters on the force and energy distribution. First, the UAD process was analyzed using a simplified drilling system model, and the relationship between the axial and tangential forces was investigated using a single PDC cutter cutting model. Then, a finite element analysis model that considers rock heterogeneity was used for the analysis. The drilling process, element damage situation, and broken form of the borehole bottom of conventional drilling (CD) and UAD were compared, and the impact of amplitude, frequency, and rotary speed on the weight on bit (WOB), torque, cutting force, and energy consumption were evaluated. Finally, laboratory experiments on PDC micro-drilling for different drilling conditions were conducted to verify the effectiveness of UAD. The results indicate that during rock-breaking using UAD, the PDC cutter periodically penetrated and broke away from the rock with ultra-high frequency, causing a large amount of damage to the rock. The frequency and amplitude significantly influenced the UAD: when the vibration frequency was between 25 and 35 kHz, the force state of the PDC cutter greatly improved compared with that of CD, and the effect of ultrasonic load reached the maximum at 33 kHz; when the amplitude was between 10 and 50 μm, WOB and torque decreased significantly and the effect of ultrasonic load improved with increase in amplitude, but the rotary speed had little effect on the torque and WOB of UAD. During the laboratory experiments, the drilling efficiency and rate of penetration (ROP) improved on using UAD. When the WOB was 100–200 N and the rotary speed was 300–400 rpm, the efficiency of ultrasonic rotary drilling to improve the ROP increased by 14.7–23.4%.

드릴링 가공을 위한 초음파 유닛 설계

With the development of new alloys and composites, existing drilling techniques have technical constraints for machining difficult-to-cut materials. To overcome these constraints, researchers have developed various drilling methods, including ultrasonic-assisted drilling (UAD). An ultrasonic spindle with a 30 kHz resonant frequency was designed to apply UAD to hole processing. The resonance frequency and vibration mode were predicted using the finite element method (FEM), and a vibration nodal plane was selected. The resonance frequency and impedance characteristics of the ultrasonic spindle were determined using an impedance analyzer, and an error of approximately 1.9% was predicted using the FEM. Next, the vibration characteristics of the ultrasonic spindle were analyzed using a laser displacement system. The vibration displacement tests showed amplitudes of 39.7 and 0.5 μm at the end of the drilling tool and the nodal plane, respectively. The design validity of the manufactured ultrasonic spindle was demonstrated based on experimental drilling results.

Study on the mechanism affecting the quality of micro-hole in ultrasonic-assisted drilling of high-speed circuit boards

High-speed circuit boards are created to meet the high-speed signal transmission requirements of 5G communication technology, but the non-polar resins, flat glass fibers, and multiple and hard fillers used for this purpose have posed new challenges to their micro-hole processing. The quality of micro-hole has always been a decisive factor in board performance. Therefore, this paper aims at proposing a new processing method for improving the micro-hole drilling quality of high-speed circuit boards. By establishing an ultrasonic-assisted drilling tool motion model, analyzing the changes in drilling method, material deformation, chip breakage, and chip removal during ultrasonic-assisted drilling of printed circuit boards, the influence mechanism on micro-hole quality during ultrasound-assisted drilling is studied prudently. Besides, an experimental platform for ultrasonic-assisted drilling is designed and built, and single-factor experiments for verification of ultrasonic effects, optimization of drilling parameters, and orthogonal experiments for ultrasonic-assisted drilling of high-speed circuit boards are conducted on this platform. The experimental results show that the loading of ultrasonic vibration has made an obvious improvement on several machining defects including hole wall roughness, entrance burr, and nail head in micro-hole drilling of high-speed circuit boards. In addition, the influence order of each processing parameter and a better combination of them are discovered, which provides a theoretical research basis and instructions for the improvement of micro-hole quality of high-speed circuit boards.