Thrust Force Reduction Research Articles

Drilling parameter optimisation for three-dimensional prints of acrylonitrile butadiene styrene

Abstract Over the past decade, additive manufacturing has transformed the industry, leading to a range of innovative products. In this study, the acrylonitrile butadiene styrene specimen was produced using the fused deposition modeling process. To assess the effectiveness of additive manufacturing parts in final product development, it’s crucial to establish the optimal drilling process parameters to minimize thrust force and torque. The investigation utilized two different drill geometries. Drilling with an end mill resulted in a 24.22% reduction in thrust force and a 12.37% decrease in torque compared to using a twist drill. Additionally, factors such as orientation, infill density, feed rate, and drill geometry have a significant impact on drilling forces.

Experimental evaluation and optimization of parameters affecting delamination, geometrical tolerance and surface roughness in ultrasonic drilling of 3D-Printed PLA thermoplastic

Ultrasonic drilling is a suitable process to enhance the generated surfaces by additive manufacturing. In this study, polylactic acid was selected as the workpiece. The examination parameters were thrust force, delamination, geometrical tolerance, chip adhesion, hole wall morphology and surface roughness. It was explained that the harmonic movement of drill bit in ultrasonic drilling reduced thrust force, delamination, circularity, cylindricality and surface roughness up to 14.5%, 3.7%, 44%, 38%, 20% respectively and removed chip adhesion. Furthermore, number of end-mill flutes was examined and observed that 4-flutes compared to 2-flutes induced reduction in thrust force, delamination, circularity, cylindricality and surface roughness up to 15.2%, 2%, 7.5%, 18.9%, 12.5% respectively. Besides, analysis of variance was established to determine the significant parameters. Finally, non-dominated sorting genetic algorithm-II technique was implemented in order to carry out multi-response optimization.

Investigating Twist Drill Design Influence on Thrust Force and Surface Roughness in Drilling AFRP/ Al7075-T6 Stacks Materials

Drilling Aramid Fiber-Reinforced Plastic (AFRP) presents unique challenges when compared to drilling other composite panels. These difficulties arise from the high-toughness characteristics of aramid fibers, which exhibit a tendency for ductile deformation during the drilling process. This research explores the influence of drill bit design on the drilling process stack-up materials, which comprise Aramid Fiber Reinforced Plastic Composite Laminates (AFRP) and Aluminum Al7075-T6. Three distinct bit designs were employed in the experiment, conducted on a Computer Numerical Control (CNC) machine operating at a spindle speed of 2000 rev/min and a feed rate of 0.05 mm/rev. To measure thrust force during drilling, a dynamometer was integrated into the setup. Subsequently, a roughness tester was utilized to assess the hole surface roughness of the stack-up materials. For AFRP materials, the w-point drill design emerged as the optimal choice, reducing thrust force by approximately 5% to 13% compared to other drill bit designs. Conversely, for Al7075-T6 panels, the tapered web drill design demonstrated exceptional results, lowering thrust force by approximately 21% and 50% in comparison to burnishing and w-point drill bits, respectively. In terms of hole surface roughness, the burnishing drill type consistently produced the smoothest surfaces, boasting significant improvements of 44% and 82% when compared to the tapered web and w-point drill bits for AFRP panels. Similarly, for Al7075-T6 panels, the burnishing drill type consistently outperformed the tapered web and w-point drill bits by 74% and 88%, respectively, in achieving a superior hole surface finish. These findings underscore the critical importance of selecting the appropriate drill bit design to optimize thrust force reduction and hole surface quality when working with stack-up materials.

Sustainable approach for machining of Ti6Al4V using micro-pillar textured turning tool insert

The use of cutting fluids (CF) in metal cutting is questioned due to environmental and biological impacts, encouraging the adoption of dry machining to minimize these effects. However, dry machining accelerates tool wear, particularly in difficult-to-machine materials like Titanium and Nickel alloys. Approaches, such as rake surface texturing, address this challenge and promote sustainability in metal cutting. This study explored the impact of an innovative micro-pillar texture pattern fabricated using a combination of Laser Beam Micro Machining (LBμM) and Reverse Micro Electrical Discharge Machining (RμEDM) for the dry machining of Ti6Al4V. The investigation considers various parameters, including tool wear, contact length, titanium adhesion, cutting forces, cutting temperature, and chip morphology. An indirect approach was adopted to estimate the temperature of the tool tip using the temperature measured at a distant location. Implementing the textured tool with 15 μm deep micro-pillars in the dry machining of Ti6Al4V exhibited the best overall performance for various responses. A notable reduction of more than 40% for both tool-chip contact length and titanium adhesion, compared to a plain tool, indicated a perceptible decrease in the seizure zone at the interface. Moreover, the textured tools demonstrated a remarkable maximum reduction of 56.4% in flank wear, ensuring the prolonged retention of a sharp cutting edge. The responses for contact length, adhesion, and flank wear contributed to an 18.8% decrease in cutting force and a substantial 45.7% reduction in thrust force. Force analysis further confirmed the directional independence of the texture pattern. Under the influence of surface texturing, chip morphology changed to shorter, untangled, and tightly curled, with a 30.8% reduction in curl radius. A theoretical estimation based on the minimum energy approach was also performed to demonstrate an increment in the shear plane angle.

Analysis of drilling behavior of flax/PP composites

ABSTRACT The current research investigation aims to use and compare three different population-based optimization approaches to optimize the operating factors of drilling process to reduce thrust force (TF) and subsequently delamination in flax/PP laminates. Five different tool point geometries and three levels of spindle speed (SS) and feed rate (FR) were considered. Analysis of variance indicated that drill point geometry was most significant parameter affecting the TF, whereas SS had the most negligible impact. Moreover, the lowest and maximum TF and delamination factor (DF) were recorded for the U-shape drill bit and 135°- point angle twist drill bit, respectively. The outcome of the experimental investigation revealed that a low FR value (0.05 mm/rev) and medium-range SS value (1500–1800 RPM) were optimum parameters for each drill geometry. Although all optimization techniques provided almost the same optimum values, but TLBO (teaching learning-based optimization) technique’s convergence rate was fast compared to others.

Evolutionary Algorithms for Optimization of Drilling Variables for Reduced Thrust Force in Composite Material Drilling

This study aims to optimize drilling variables to reduce the thrust force required for drilling composite materials. The optimization process involves using evolutionary algorithms such as particle swarm optimization (PSO) and genetic algorithm (GA) to determine the best combination of drilling parameters, including drill speed, feed rate, and point angle. The objective is to minimize the thrust force required for drilling while maintaining the desired quality of the drilled holes. ANOVA and regression analysis is implemented to discuss the impact of drilling variable on the thrust force. The results demonstrate that the proposed approach is effective in reducing thrust force and improving drilling efficiency. The optimized drilling parameters obtained can be used to enhance the performance of composite material drilling processes. Performance output of both algorithms for optimization of problem is discussed in detail.

Drilling study on CFRP/Al stack with different CFRP thickness using chip-breaking step drill bit

Low-defect and high-accurate drilling is required for CFRP/Al stack assembly, while unexpected drill defects and inconsistency of hole diameter are often found in drilling different thickness stacks due to the lack of proper drilling process. First, a novel quantifying method for CFRP delamination and Al burr is proposed and a new quality indicator for hole diameter is developed to ensure the accuracy of evaluating the drilling quality. The stacks with different thicknesses were compared, and the subsequent effects of machining parameters on drilling quality were comprehensively investigated. Then considering the thrust force and drilling temperature together, the influence of thermal-mechanical interaction on the hole defects was elucidated for the first time in drilling different thick stacks. The results show that the thicker stacks increased the drilling temperature for the prolonged tool/material engagement time, and that the stiffness and strength of drilled material were reduced progressively as the higher temperature, leading to the lower thrust force. For the CFRP delamination, the thickness of the stack is found to be another significant factor determining the delamination damage, and a better CFRP quality can be obtained in drilling thicker stacks. The height of Al burr increased with the thickness increased due to the main effects of the increased temperature, but which decreased and then increased with the feed because the decreased drilling temperature played at low feed while decreased thrust force at a high feed played a decisive role separately. Smaller diameter deviation was found in drilling thicker stacks, for the reduced thrust force leading to the decreased deformation. Besides, the diameter deviation decreased with feed increased as the reduced temperature played a main role at low feed, while diameter deviation increased at a high feed because the thrust force increased. Finally, a multiple-objective optimization was modelled, and optimum drilling conditions for achieving desired hole quality were determined with the chip-breaking step drill bit for drilling different CFRP/Al stacks.

Optimization of process variables in drilling of carbon fiber reinforced plastics using various multi criteria decision making approaches

AbstractCarbon fiber‐reinforced polymers are one of the lightweight materials used in structural design due to their exceptional mechanical performances. The drilling operation is indispensable as it facilitates the assembling of various manufactured components. However, drilling of fibrous laminates is deemed difficult in comparison to the traditional metals because of the anisotropic and non‐homogeneous nature. The present work addresses the parametric effect on the drilled hole delamination and further reduces it with an optimal combination of parameters for multi‐objectives using different multi‐criterion decision‐making techniques. Initially, the response surface‐based regression model of delamination as a function of three static inputs has been developed, further revised with induced thrust as well as mean torque for the improvisation of the prediction capability. Finally, for the overall improvement, a decision‐making model has been used that includes grey relation analysis, technique for order performance by similarity to ideal solution, and VIšekriterijumsko Kompromisno Rangiranje method. The delamination was found to be minimum at a low drill point angle (100°), high spindle rotation (2150 min−1 ), and low feed rate (0.025 mm/rev) due to reduced thrust force. The mean absolute prediction error was significantly improved considering root mean square torque rather than axial thrust with process variables.

Interaction between Micro-Amplitude Vibration and Thrust Force in Ultrasonic-Vibration-Assisted Drilling of Glass-Fiber-Reinforced Plastics

This research intends to investigate the effect and potential of the ultrasonic vibration of tools for drilling glass-fiber-reinforced plastics (GFRPs), especially with the aim of minimizing the thrust force. As an important parameter to characterize the vibration intensity, the vibration amplitude has a significant effect on the thrust force in the ultrasonic-vibration-assisted drilling (UVD) of GFRPs. It has been observed that the thrust force also influences the vibration amplitude, which may eventually result in a failure of the vibration. In this study, a method for the in-process measurement of the vibration amplitude was introduced to enable the investigation of the interaction between the thrust force and vibration amplitude in UVD. It was investigated how variations of the thrust force and vibration amplitude influence each other from holistic and individual perspectives. The critical condition was identified to ensure a sufficient ultrasonic vibration effect during drilling. Additionally, UVD experiments with different vibration amplitudes were carried out. The interaction between thrust force and vibration amplitude in UVD was revealed. It can be concluded that the combination of a moderate thrust force, low vibration amplitude reduction ratio, and high vibration amplitude increases the thrust force reduction ratio and secondly that an excessive thrust force undermines the effect of ultrasonic vibration. This provides an in-depth understanding of the interaction between vibration and thrust force in UVD, and helps to further improve the effect of ultrasonic vibration.

Machining GLARE fibre metal laminates: a comparative study on drilling effect between conventional and ultrasonic-assisted drilling

GLARE laminates are multi-layered metal-composite materials created from bonding sheets of metallic alloys with carbon or glass fibre layers. The application of hybrid-conventional machining processes such as ultrasonic-assisted drilling (UAD) is becoming of great interest to the aerospace industry due to its capability in reducing the cutting forces and tool wear which are directly responsible for drilling-induced delamination. There is rich literature on the conventional drilling (CD) of GLARE, but no work reported using UAD process. This study will fill this gap and investigate the UAD of GLARE laminates using an indigenously developed UAD system. The influence of spindle speed and feed rate on thrust force and surface roughness metrics (Ra and Rz) were investigated under CD and UAD regimes. The quality of the borehole and damage mechanisms in the laminate constituents was examined using scanning electron microscopy (SEM). The contribution of the drilling parameters on the measured outputs was further evaluated using the analysis of variance (ANOVA) statistical analysis. It was found that UAD resulted in a significant reduction in thrust force by up to 65% while surface roughness metrics Ra and Rz were unaffected by the type of drilling process used. SEM analysis showed irregular and fuzzier surfaces in glass fibre layers in holes machined using UAD due to the longitudinal vibration of the tool.

Drilling-Induced Damages in Hybrid Carbon and Glass Fiber-Reinforced Composite Laminate and Optimized Drilling Parameters

Hybrid carbon and glass fiber-reinforced composites have attracted significant research interest for primary load-bearing structural components in the field of aviation manufacturing owing to their low weight and high strength to weight ratio. However, the anisotropic and heterogenic nature of carbon and/or glass fiber-reinforced composite prevents high machining quality due to the directionality effect of fibers in the polymer matrix. As such, this study investigates the effect of drilling process for hybrid fiber-reinforced composite and reports optimal drilling parameters to improve the drill quality. Experimental studies indicate that an increased point angle (i.e., from 80° to 120°) resulted in low delamination upon entry due to reduced thrust force, which in turn produces better surface finish with minimal tool wear. The optimal feed rate (0.2 mm/min) ensures lower delamination at entry, since higher feed rates can increase the thrust force due to elevation in the shear area or raise the self-generated feed angle, which in turn reduces the effective clearance angle. To this end, drilling parameters were optimized using Dandelion optimizer (DO)—a cutting-edge metaheuristic search algorithm (MSA). We report the excellent consistency of DO to solve the proposed drilling optimization problem while achieving promising results as ascertained by the small standard deviation values.

Novel crescent drill design and mechanistic force modeling for thrust force reduction in bone drilling

Bone drilling tends to cause mechanical damages and thermal necrosis in the vicinity of the drilled hole, which can deteriorate the surgery quality and patients’ recovery. Understanding the cutting forces generation mechanism is crucial in controlling thrust force and bone temperature for optimum tool design. In this study, a novel crescent drill bit featuring an improved positive rake angle distribution was designed to reduce the thrust force and temperature elevation. On this basis, a mechanistic model for predicting thrust force and torque was proposed for drill bits with different geometries (twist drill and crescent drill). The proposed model was established in the polar coordinate system to precisely calculate the curvilinear integral of the crescent cutting edges. Drilling experiments were carried out using two types of drill bit under different cutting conditions and results showed that our proposed model agrees well with the experimental data. The experimental results also demonstrated that our tool design can significantly reduce the thrust force and reduce the bone temperature below the thermal threshold without coolant, providing a clinical option for coolant free drilling.

A Preliminary Study: Influence of Sub-Surface Ground Condition on the Tunnel Boring Machine Performance

Tunnelling through various ground condition affects the performance of Tunnel Boring Machine (TBM). Previous researches have conducted studies to explain on this relationship. However, a more localised influence of Malaysian Kenny Hill Formation subsurface condition towards TBM drive are yet to be carried out. This study will assess this relationship at areas nearby Museum Station during the Klang Valley Mass Rapid Transit (KVMRT) Line 1 with a length span of 540m. After the data collection from TBM and borehole report, data analysis was carried out namely using cutter head, thrust cylinder and subsurface profiling. These data were plotted based on the chainage and tunnel ring number. It is observed that subsurface profile at Ring 9 and Ring 11 required a higher thrust force due to its cohesive soil condition and inclusion of sandstone rock. However, Ring 10 is vice versa as there were more non-recovered soil samples at the specified area. The reduction of thrust force eventually increases the speed of TBM penetration. Thus, a clear relationship showing that subsurface condition highly influences the TBM drive.

Experimental and scale-span numerical investigations in conventional and longitudinal torsional coupled rotary ultrasonic–assisted drilling of CFRPs

Longitudinal torsional coupled rotary ultrasonic–assisted drilling (LTC-RUAD) technology is introduced to improve the surface roughness of the hole-wall and solve the tear, burr, and delamination of carbon fiber–reinforced polymers (CFRPs) induced by large thrust force and torque during conventional drilling (CD). An experiment and scale-span numerical investigation of drilling CFRPs were presented for both the CD and LTC-RUAD processes in this study. A drilling experimental platform using the LTC-RUAD was built via a novel independently designed and manufactured LTC-RUAD vibration actuator, while the drilling experiments involving T700S-12 K/YP-H26 CFRP specimens with different process parameters were carried out by adopting the different ultrasonic vibration amplitude (UVA) in the longitudinal and torsional directions. Then, a three-dimensional (3D) scale-span FE simulation model of the CD and LTC-RUAD which applied the different UVA using tapered drill-reamer (TDR) is developed to find more details about the effects of machining quality of the holes. Experimental and simulation results revealed that the maximum average thrust force reduction is observed to be as high as 30% under certain drilling conditions, and the maximum average thrust force and the delamination factor of the drilled hole shows a “concave” trend with the increase of the UVA. The quality at the exit of the drilled hole is best when adopting Sr = 2000 rpm, Sf = 0.01 mm/rev, Alon = 7.02 μm, and Ator = 9.29 μm in the LTC-RUAD. The delamination factor is only 0.054, and the damage factors are reduced by 69.67% compared with CD.

Drilling induced delamination assessment of nanoparticles reinforced polymer matrix composites

The knowledge of polymer matrix composites machinability has increased with its rise in multi-field structural applications. Drilling of polymer matrix composites is required to achieve structural integration with greater accuracies. Delamination due to drilling affects the material strength and it occurs at both the entry and hole exit planes. The delamination on the exit plane is critical. The effect of nano-fillers on drilling-induced delamination of reinforced plastics has not been documented extensively and in this article, an attempt is made to explore the application potential of montmorillonite clay and graphene with amine functionalization in minimizing delamination through toughening the epoxy matrix. Experimentation was based on Taguchi’s L16 approach. The delamination factor and circularity ratio were analyzed using an image processing technique in Matlab and Image J. To evaluate the effects of various parameters and parameters interaction effect on the delamination factor, ANOVA was employed and Signal/noise ratios were calculated. The mathematical models were developed for delamination. It was observed that the reduction in the delamination factor was observed in nanoclay and graphene reinforced polymer matrix toughened composites in comparison to the base composites with a reduction in thrust force, specific cutting energy, and increase in circularity ratio.

Machinability studies on boron carbide and graphite reinforced aluminium hybrid composites

The effect of machining parameters on the thrust force, torque and burr height while drilling Al 2618, Al2618 with 10% boron carbide (B4C) and Al2618 with 10%B4C and 5% graphite (Gr) hybrid composites are addressed. The composites are produced using a process of liquid metallurgy. The findings indicate that, feed rate had a significant impact on thrust force and the height of the exit burr. The Al2618 + 10% B4C-5%Gr reinforced hybrid composites exhibit smaller thrust force and burr height in contrast to the Al2618 + 10% B4C composite. The reduced thrust force, torque and burr height was due to the strong graphite surface lubrication properties. The chips produced while machining graphitic composites are discontinuous, and hence beneficial.

Effect of Silica Rich CRT on Thrust Force, Temperature and Surface Finish in Drilling Magnesium Hybrid MMC

The current study focuses on developing Mg/CRT/BN hybrid composite and optimization of reinforcement and drilling parameters for better surface finish, reduced thrust force and temperature while drilling the composite. The specimens are produced through powder metallurgy method by incorporating silica rich cathode ray tube (CRT) panel glass powder having rich silica content and boron nitride. Along with CRT particle size (10, 30 and 50 μm) and proportions (5, 10, 15 wt.%), machining parameters namely cutting speed, feed rate and diameter of the tool were considered for optimization. The results reveal that the surface roughness, thrust force and temperature in drilling rose with raise in reinforcement size and weight %. Analysis of Variance (ANOVA) results indicate that every one of the input constraints have considerably affected the response variables. The regression model formed possesses enough capability to predict the output variables that too with minimal error. The optimum parameter combination for multi quality characteristics predicted by GRA gives better results.

Effect of thrust force, torque, and induced temperature on Kevlar reinforced composites during drilling process

The present study aims at finding optimum drilling process parameters to reduce thrust Force and torque. Heat induces in drilling zone during drilling process has analysed by thermal image camera. The kevlar 49 reinforced epoxy composite specimen has utilized for experiments. Drill bits utilized for the experiments namely, Twist, Core, step cone, and candle stick. According to the experiment results feed rate is most influencing on thrust force followed by torque. A core and candlestick drill bits has produced lesser thrust force compared to other drill bits. Heat generated in drilling zone during drilling process has higher for step cone and standard twist drill bits compared to glass transition temperature of matrix. Hence, matrix has not able to providing necessary support to fiber in composite. Candle stick and Core drill bit has been providing lesser thrust force, torque and defect free machining at lower spindle speed and feed rate.

Simplified Three-Vector-Based Model Predictive Thrust Force Control With Cascaded Optimization Process for a Double-Side Linear Vernier Permanent Magnet Motor

In order to reduce thrust force and stator flux ripples, this article proposes a simplified three-vector-based model predictive thrust force control method for a double-side linear vernier permanent magnet motor. First, a simplified control set is designed to select two active voltage vectors (VVs) in the prediction stage, instead of evaluating redundant VVs. Null VVs are applied to adjust the amplitude of the modified VV, which can realize a full-range modulation by the predefined cost function. To simplify the tuning work of the weighting factor, the variables in the cost function only consider the stator flux term. Then, the duration time of the selected VVs is distributed reasonably through a novel cascaded optimization process. Also, the deadbeat principle is adopted to calculate the duty cycle. With the proposed method, the thrust force and stator flux ripples can be considerably minimized. The simulated and experimental results are conducted to verify the proposed control method.

Effect of feed condition on thrust force and torque during continuous and step-by-step drilling of cortical bone

Abstract Chip evacuation is one of the fundamental difficulties during continuous drilling of the cortical bone. As the drilling process progresses, discontinuous chips tend to cluster together and clog the drill flutes, which can result in increased temperature, poor hole quality, elevated thrust force and torque, and can even cause the drill bit to break. In this study, continuous and step-by-step drilling processes of the cortical bone were conducted to investigate the thrust force and torque using experimental and numerical modeling methods. By using the finite element method, an elastic–plastic constitutive model was employed to predict the thrust force and torque experienced during bone drilling, and a series of drilling tests was conducted. The experimental results showed a significant increase in the thrust force and torque owing to the chip clogging during the continuous drilling process while this increase was not observed in the simulations. It was shown that the step-by-step drilling method can reduce the increased thrust force and torque during the drilling of cortical bone, and the numerical results of this drilling process were demonstrated to be consistent with the experimental ones. The reduced thrust force and torque indicated that the chip clogging may be reduced by using the step-by-step drilling method, and the numerical results suggested that the finite element model can be used to assist surgeons in selecting drilling conditions to control the process in step-by-step drilling of the cortical bone.