Hole Surface Quality Research Articles

Comparative Analysis of Hole Surface Quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate With 90°/0°/90° Ply Orientation Angle

Comparative Analysis of Hole Surface Quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate With 90°/0°/90° Ply Orientation Angle

Experimental investigation of powder mixed micro-electrical discharge drilling on SS304 substrate

The present work investigates the effect of incorporating molybdenum disulfide (MoS2) powders into the dielectric liquid medium to carry out micro electrical discharge drilling (micro-EDD) on SS304 sheets (1 mm). Different process parameters (i.e., voltage, frequency, and duty factor) are taken into account to explore their performance on the responses such as taper angle (TA), heat affected zone (HAZ), and over cut (OC). Taguchi design of experiments (L9 orthogonal array) is used to conduct the set of drilling experimentation. The results show that the introduction of MoS2 micro-powder in dielectric fluid improved the drilled hole surface quality. The maximum HAZ was found to be at 50 V, duty factor 70%, and frequency of 10 kHz (62.92 µm) without powder.

Comparative Analysis of hole surface quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate with 45°/0°/45° Ply Orientation Angle

Comparative Analysis of hole surface quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate with 45°/0°/45° Ply Orientation Angle

Experimental analysis of the influence of discharge gap on EDM performance

In order to reduce the machining time and improve the surface quality of holes, a high speed self adjusting electrical discharge machining (EDM) approach is needed with independent flushing system that were able to remove the debris in the machining process. With the change in the gap distance and depth of the hole drilled, the electrode automatically adjusts the gap with the help of a linear actuator. For that, the optimum gap distance for getting maximum result is crucial. Taguchi L27 orthogonal array technique is used for the preliminary experimental analysis. The study revealed that discharge gap which is proportional to the gap voltage is the most influential parameter that affects the surface finish and material removal rate. The formation mechanism of the hole in the copper plate had found out, in order to get the optimum gap distance for the maximum MRR, TWR, and ROC. The results from the comparison experiment shows that the best result will be get at 0.5 mm gap distance and this can be taken as the optimum gap distance for the automatic feeding mechanism. In addition, low voltage and current would benefit for the EDM process working in micro level and for the removal of the recast layer.

Experimental research on micro hole drilling of polycrystalline Nd:YAG

Polycrystalline Nd:YAG materials have wide applications in solid-state lasers. In this study, micro hole drilling experiments were performed on polycrystalline Nd:YAG using a polycrystalline diamond micro drill. The hole diameter, edge chipping, and hole wall surface quality were examined in detail. The results showed that the hole diameter was slightly larger than tool diameter. A diameter error of less than 5.5% was achieved. The edge chipping at the entry hole was formed by the encircled petal shape exfoliations, which were produced by the indentation and rotation movement in the drilling entry stage. Edge chipping at the exit hole was generated by an entire piece of exfoliation, which was produced by a circle of microcracks around the tool tip propagating to the bottom surface in the drilling exit stage. The edge chipping width at the entry hole was smaller than that at the exit hole. Based on different material removal modes, the hole surface morphology was classified into three types: ductile removal, coexisting ductile and brittle removal, and brittle removal. The hole surface quality mainly depended on the proportion of the brittle fracture to ductile removal surface.

Optimization of Honing Surface Roughness of Carburized Holes Based on GRA-RSM

The carburized holes processed by ordinary internal grinding are prone to burn, crack, and low efficiency. Honing has a superior machining efficiency and cooling effect compared to traditional internal grinding. In this paper, we innovatively apply honing to carburizing hole grinding and propose an effective optimization scheme to enhance the surface finish of carburized holes. We set up an experimental system to explore the influence law of honing head rotation speed, axial reciprocating speed, grain size, and single grinding depth on surface roughness. Based on the grey correlation and response surface method, we propose a method to optimize the honing parameters of carburized holes and establish a prediction model, which has an R2 value of 0.9887, indicating that the model fits well. We verify the validity of the model by the root mean square error of 0.012 between the measured and calculated values. Based on the model, the optimal parameters of roughness (Ra) is obtained and verified by experiments. Compared with the original honing parameters, the surface roughness quality is improved by 25.8%. It shows that the optimized honing process based on the GRA-RSM method improves the surface quality of carburized holes significantly.

Minimum quantity lubrication and heat-assisted friction drilling of AA7075-T6 aluminum alloy

In this study, friction drilling was performed for AA7075 - T6 alloy under dry, minimum quantity lubrication (MQL), heat, and heat + MQL process environments. The aim is to achieve the optimum bushing profile by increasing the productivity of friction drilling in different process environments. Friction drilling experiments were carried out at constant speed and feed rate; the effects of the drilling environment on thrust force, temperature, hole bushing profile geometric properties, hole surface quality, thread stripping strength, and micro hardness values were investigated. The test results revealed that the drilling environment directly affects the formation of heat and thrust forces during the process. The best surface roughness (Ra) value was achieved in the heat environment with 2.61 µm. Thread stripping experiments showed that the heating process improved the thread stripping strength of AA7075-T6 by 14.65% when compared with the dry environment. The results revealed that the main damage mechanism occurred in the transition zone from the heat-affected zone (HAZ) to the base material (BM) in the tensile strength test on the heat process environment specimen, while the roots of threads were affected in other process environments. The different microhardness values were measured in the thermo-mechanically affected zone (TMAZ), HAZ, and BM formed during the process.

Investigation of the Effect of Drill Bit Feature on Hole Surface Quality and Tool Wear

Drilling operations have an important role in manufacturing industries and the application range is about 33% among the machining methods. In drilling processes, hole quality is affected by workpiece material, drilling parameters, drill diameter, drill bit features. In this study, the surface quality of the hole and the drill bit wear were investigated experimentally when drilling AISI 1040 steel and Al7075 aluminum workpieces with twist drills. Three different types of twist drill bits (polished, rolled and TiN coated) with diameters of 8 mm and 10 mm were used for drilling. Hole surface roughness was investigated at the hole entry and hole exit. While revealing the surface quality change at the hole entry-exit, the effect of the drill feature difference on the surface quality has been tried to be determined. In general, hole surface quality decreased with increasing drill bit diameter when drilling both materials. The lowest surface roughness values were obtained in the use of TiN coated drill bits. Drill bit wear was also measured in the study, and it was seen that the drill bit wear increased with increasing drill bit diameter. The least drill bit wear value was also observed in TiN coated drill bits.

Analysis of Solid Carbide Drilling Performance on AISI 316L Austenite Stainless Steel using MQL (Minimum Quantity Lubrication) using Peck Drilling Approach

Minimum Quantity Lubrication (MQL) minimizes refrigerants and lubricants mixed with air to foster environmental sustainability. Austenitic AISI 316L stainless steel is often used for the aviation, biomedical equipment and food appliances. However, low machinability of this material makes it difficult to cut resulting low hole surface quality. The objective of the study is to evaluate the drill performance of solid carbide tools while drilling AISI 316L austenite stainless steel and to study the effect of drilling parameters, cutting speed (Vc), feed rate (Fr) and drill geometry (point angle) on tool life, surface integrity and holes accuracy. Solid carbide drilling performance analysis on AISI 316L Austenite Stainless Steel using MQL was assessed in terms of tool life, surface roughness, and hole accuracy. Investigation for optimal conditions of cutting speed, feed rate and point of angle when drilling AISI 316L austenite stainless steel would obtain the optimum output indicates longer tool life, better surface roughness and adequate accuracy in high-speed machining conditions. This MQL oil-air flow is accurately measured and sent to the drill tool edge. The cutting speeds applied for the machining process are 100m / min, 130m / min and 150m / min. For feed rate parameters, the selected values are 0.05mm / rev, 0.1mm / rev and 0.15mm / rev. Rotational drill angles are 110 °, 120 ° and 130 °. The peck drilling investigation is performed on high-speed milling machines keenly will provide guidance to produce good and optimal machining settings of cutting speed, feed rate and angle point to others when they want to drill a hole.

Surface quality and geometric accuracy control of fuel nozzle single-pass honing

Fuel nozzle is a key part of aero-engines. Due to the particularity of fuel nozzle’s working environment, the high machining requirements for the surface quality and geometric accuracy of nozzle hole were put forward. The existing process is difficult to meet the machining requirements, so a new process is proposed, which is called the flexible single-pass honing. For the novel single-pass honing tool with diameter less than 1 mm, the laws are not very clear, so studies were carried out. Firstly, a novel cutting force model of single-pass honing was established, which explains the relationship between force and machining parameters. Based on the cutting force model, the influence laws of honing parameters on surface roughness, bore diameter, and shape accuracy were explored detailedly. Finally, according to the machining requirements of fuel nozzles, the honing process optimization was carried out, and the optimal parameters were obtained. Furthermore, precision control of surface quality and geometric accuracy for fuel nozzle single-pass honing was realized.

Friction drilling of AA7075-T6 and AZ31B alloys under dry and oil containing ceramic particulates

This study investigates the friction drilling behaviors of AA7075-T6 aluminum and AZ31B magnesium alloys containing ceramic powders of B4C, SiC, and Al2O3 under dry and minimum quantity lubrication (MQL). The aim is to create a composite structure while applying the pressure of a drilling tool on the hole surface when adding ceramic powders into the cutting oil during frictional drilling. Friction drilling tests are performed at a constant spindle speed and feed speed, and the effects of dry and cutting oil mixtures containing ceramic particulates on the thrust force, temperature, hole surface quality, bushing profile, and thread stripping strength of the specimens are investigated. The results revealed that ceramic particles penetrated through the hole and created a composite structure on the surface. The dry friction drilling of AA7075-T6 and AZ31B yielded acceptable surface quality. However, the surface quality worsened considerably during the friction drilling of AA7075-T6 using the oil mixture, whereas the surface roughness and hole bushing of AZ31B magnesium alloys are not negatively affected by the ceramic containing oil mixtures. Petal formation and cracks appeared in the hole profiles of the AA7075-T6 aluminum alloy. Thread stripping tests indicate that the ceramic-particle- containing oil mixtures enhanced the thread shear strength of AA7075-T6 by 19.2 %, and the highest shear strength of 56.78 kN is achieved using the Al2O3 containing an oil mixture. The oil mixture-containing B4C ceramic particles improved the thread shear strength of AZ31B by 7.7 %.

Mechanisms and evaluation of the influence of cutting temperature on the damage of CFRP by helical milling

The quality of holes machined in carbon fibre reinforced plastic is vital to the strength of CFRP/Ti stacks. In this study, the influence of cutting temperature upon hole damage of CFRP in CFRP/Ti stacks under helical milling was compared with and without the presence of an underlying Ti. The cutting forces, exit quality, wall surface and subsurface quality of CFRP hole were analysed. And proposing a method to evaluate subsurface damage, and combined with the tensile test to study the effect of subsurface damage on the mechanical properties of CFRP. The results suggest that titanium alloy slightly exerts an effect on the cutting force and exit and wall mass of CFRP holes, yet dramatically affects their subsurface mass. High cutting temperatures may degrade the performance of the CFRP resin matrix, which may cause further subsurface damage closest to the hole exit. The proposed method is used to evaluate subsurface damage. It was most serious in the fibre layer near the hole exit and gradually decreased with distance from the exit. The results of this study will help improve the machining quality of CFRP/Ti stacks.

Minimization of thrust force and surface roughness during MQL coolant drilling on tool steel using BPNN-ACO

The excessive thrust force that generated during the minimum quantity lubrication (MQL) drilling process of tool steel can lower the hole surface quality. Hence, it is necessary to properly choose the combination of machining variables to minimize thrust force (TF) and hole surface roughness (HSR) simultaneously. This study underlines the modelling and minimizing the thrust force and hole surface roughness developed during MQL drilling process by integrating a backpropagation neural network (BPNN) method and ant colony optimization (ACO). The varied drilling parameters were type of drill bit, drill point angle, feeding speed, and cutting speed. The optimum BPNN architecture could be obtained by using 4-20-2 network architecture with tansig activation function. The optimum MQL drilling parameters that can minimize TF and HSR simultaneously were HSS M2 drill bit, 107° of drill point angle, 0.045 mm/rev of feeding speed and 36 m/min of cutting speed.

WITHDRAWN: Parametric analysis on the effect of process parameters in ECDM through changes in geometry of tool electrode in ECDM

The prodigious characteristics of glass require scrupulous investigation, so it is required to understand the behavioural performance of glass undergone through the techniques of micromachining. Currently electrochemical discharge machining is proved to be auspicious in fabrication of glass components, in the world of miniaturization. Although various parameters are already investigated, which effect the surface quality of micro hole fabricated through electrochemical discharge machining. Likewise the effect of tool electrode by utilising its different shapes, materials have analysed in past. But the consequence of distorted geometry of the tool electrode while electrochemical discharge machining, is not yet fully understood. In this research work, the microscopic investigation of tool electrode was utilised with the aid of image processing along with the modelling techniques at different combinations of process parameters while electrochemical discharge machining of borosilicate glass. And, the upshot of the study will be used to analyse the effect of distorted geometry of tool electrode at various levels during electrochemical discharge machining.

Comparative evaluation of machining processes for making holes in GLARE fiber metal laminates

Drilling is widely used in manufacturing industries for making holes in a variety of components. However, dissimilar material properties of fiber material laminates (FML) makes hole processing a challenge. Also, high thrust load damages the material thereby affecting the hole surface quality and dimensional accuracy. This work evaluates the conventional drilling and newer helical milling process for making holes in glass laminate aluminum reinforced epoxy (GLARE) FML. The processes were analyzed considering the machining forces, surface roughness, hole diameter, and machining temperature. Magnitude of the machining forces and temperature were lower in case of helical milling process and the surface finish was found to be better when the helical hole milling process was used. Hole drilling process resulted in the generation of long continuous chips which frequently entangled around the drill bit while the use of helical hole milling process resulted in the production of powdery discontinuous chips which helped in easy evacuation. In addition, the formation of burrs was noted during the drilling process while hole milling resulted in relatively burr-free holes.

The Effect of Cryogenic Cooling and Drill Bit on the Hole Quality when Drilling Magnesium-based Fiber Metal Laminates

The interest on fiber metal laminates has increased significantly in recent years as a consequence of the request of lighter and more functional aerospace and automotive components. In such parts, drilling is essential for assembly purposes. Nevertheless, drillability of fiber metal laminates is a critical issue due to the heterogeneous mechanical and thermal properties of metals and composites. The current research work aims at understanding how to improve the hole quality after drilling of magnesium-based fiber metal laminates. To this aim, dry and cryogenic cooling was applied as well as the adoption of three different drill bits, namely uncoated drill bits, coated drill bits and spur drills. Hole size, cylindricity, roughness, entry burr height, exit delamination and fiber pull-out are considered as experimental outcomes to characterize the hole surface quality. Results show that both spur drills and cryogenic cooling can significantly improve hole quality. The process parameters combination capable to guarantee the highest surface quality is finally provided.

Parameters optimization for microcrack width in laser trepanned hole

Abstract Ceramic composite like Zirconia Toughened Alumina (ZTA) acquire with excellent toughness, high hardness and temperature resistance. These characteristics demand applications in manufacturing of ballistic body parts, cutting tool inserts, turbine blades and combustion chambers. Conventional machining methods are unsuitable to drill/cut holes in ZTA plate due to its improved mechanical properties. Researchers have found that laser beam machining has capability to drill or cut holes in structural ceramics. Formation of microcracks is inherent in laser drilled hole due to adhered layer of resolidified material and development of thermal stresses. The chances of formation of microcracks are more in laser drilling or cutting of hard and brittle material like ZTA. Sometimes, widening of microcrack propagates underneath recast layer and demolishes the hole surface quality and changes parent material properties, as well. Therefore, selection of optimum level of control factors or input process parameters became essential during laser drilling of ZTA to overcome the intensity of microcracks. In this research paper, the microcrack width of laser trepan drilled hole has been optimized using Artificial Intelligence tool such as Genetic Algorithm. Optimum result shows that microcrack width has been reduced by 17.66%. The comparative improvement has also been confirmed in SEM image.

Study on the improvement of the surface integrity and efficiency of electrical-discharge-machined TC4 titanium alloy via abrasive flow machining

To simultaneously optimize the surface quality and machining efficiency of the electrical discharge machining (EDM) processes used to produce titanium alloy quadrilateral group small hole parts, a combined “EDM + AFM” machining technology is proposed in this paper as an efficient and high-quality machining approach. In the proposed method, TC4 titanium alloy is first machined using the EDM process with graphite electrodes and the abrasive flow machining (AFM) process is then used to finish the machined surface. The effects of various electrical parameters on EDM-derived surface quality and improvements in EDM-derived quality under the application of AFM were assessed and, using the final surface roughness as a constraint condition, the effects of various combinations of EDM and “EDM + AFM” on efficiency were studied. The results revealed that the thickness and surface roughness of the superficial recast layer of the TC4 titanium alloy increase with both current and pulse width; in particular, increasing these parameters can increase the surface roughness by two to three grades. Following AFM, the alloy has a more uniform hardness distribution and the surface stress state changes from tensile to compressive stress, indicating that the combined “EDM + AFM” machining scheme can significantly enhance the surface quality of EDM-produced titanium alloy quadrilateral small group holes. The combined scheme achieves a balancing point beyond which increasing the roughness or the number of machining holes enhances either the machining efficiency or the machining surface quality. In the case of typical titanium alloy quadrilateral group small hole parts, the combined machining process can improve the finishing efficiency and total machining efficiency by 71.2% and 25.36%, respectively.

A subjective-objective evaluation method of hole surface quality in drilling CFRP-Ti stacks

Hole surface quality in drilling carbon fiber-reinforced plastics and titanium alloy (CFRP-Ti) stacks is a key factor affecting high-quality assembly and reliable usage of the structure so it need be reasonably evaluated. However, there is no standardized evaluation system of hole surface quality in drilling CFRP-Ti stacks. The existing evaluation indexes cannot meet the evaluation requirements on the surface quality of the hole. This paper proposes a subjective-objective evaluation method to evaluate the surface quality of the hole in drilling CFRP-Ti stacks. Firstly, the evaluation factors are determined by experiments, including CFRP delamination, CFRP hole entrance tears, surface roughness of CFRP and Ti, and the evaluation system is established according to defect characteristics and industry standards. Secondly, the subjective evaluation model is established based on the improved analytic hierarchy process, the objective evaluation model is established based on the entropy weight method and the subjective and objective combination weight calculation method is obtained based on the principle of minimum discriminant information. Finally, the surface quality of the hole is evaluated by subjective, objective, subjective-objective evaluation methods respectively. The result shows that subjective-objective evaluation method is more reasonable and effective.

OPTIMIZATION OF LASER MACHINING PARAMETERS ON AL-SI-MG METAL MATRIX COMPOSITE BY FIBER LASER USING TAGUCHI METHOD

Laser Drilling is practiced for engraving and cutting both metallic as well as for non-metallic materials. This paperwork is anticipated to achieve the best possible geometrically accurate and evenly surface polished laser-drilled holes by optimization of process parameters using the Taguchi method. Power, laser frequency, and laser speed are considered as process parameters whereas taperness, surface roughness, circularity, and heat-affected zone (HAZ) are recorded as responses to interrogate the surface quality and geometrical accuracy of laser-drilled holes. Minitab software is used for the optimization of process parameters by the Taguchi L9 method with 3 levels. Laser drilling operation is carried out on an Aluminium metal matrix due to its high machinability which is processed through stir casting at a temperature varying between 700-800 0C. Laser machining is performed with a dimension of 1 mm outer diameter and 1 mm depth. After machining SEM (Scanning electron microscopy) analysis is conducted in order to interrogate the responses, based on its results the HAZ, circularity, and outer diameter of the hole is procured through which the quality of the hole is identified.