Aluminum Alloy Drill Research Articles

Minimum quantity lubrication drilling of aluminium–silicon alloys in water using diamond-like carbon coated drills

The dry drilling of aluminium alloys (without using cutting fluids) is an environmentally friendly machining process but also an exceedingly difficult task due to aluminium's tendency to adhere to the drills made of conventional materials such as the high-speed steel (HSS). Diamond-like carbon (DLC) coatings improve the dry drilling performance due to their adhesion mitigating properties. In this work, improvements that are possible when DLC coated tools are used under minimum quantity lubrication (MQL) condition in drilling of an Al–6%Si (319 Al) alloy were examined. Results were compared with drilling using conventional flooded coolant. The experimental approach consisted of the evaluation of the cutting performance of DLC coated HSS drills in a distilled water spray (30 ml/h) used as the MQL agent. Two types of DLCs (non-hydrogenated and hydrogenated) with different tribological responses in H 2O testing environment were considered. The H 2O-MQL cutting of 319 Al using either type of DLC coated drills reduced the drilling torque compared to dry drilling to a level similar to the performance under the flooded condition. An added advantage of the H 2O-MQL over dry drilling was that the process was more stable; a smaller percentage of drilled holes exhibited “torque spikes”, i.e., an abrupt increase in torque, indicative of adhesion. H 2O-MQL cutting using non-hydrogenated DLC was preferred to hydrogenated DLC because it resulted in smaller built-up edge (BUE) formation and also less amount of drill flute aluminium adhesion resulting in less torque and thrust force being required during drilling.

Features of the hole shape formation during laser drilling of an ultrafine-grained aluminum alloy

It is demonstrated that the interaction of laser radiation with ultrafine-grained aluminum alloys substantially differs from that with analogous coarse-grained materials, which accounts for a change in the shape of holes formed during precise laser machining.

Experimental study and synthesis of the dynamic behaviour in high speed drilling

This paper concerns an experimental approach of vibration phenomena in High Speed Drilling (HSD) of aluminium alloys. In order to study these phenomena, different results have been chosen to illustrate that these vibrations are generated by different deformations of the drill and the machining system. The relevant parameters at the origin of these vibrations in HSD are pointed out and their influence on the quality of drilling is analysed. The effect of the drill geometry on surface quality is reported and in particular the role of the chisel edge, the helix angle which controls the sharpness of tool corner, the thickness and the number of margins which allow the drill to be held in the hole and the rigidity of the drill materialised by its overhang. Depending on its length, the drill can deform differently. The influence of the drilling conditions on surface quality has also been evaluated: the feed rate per tooth and the cutting speed as well as the rotation frequency and the feed speed. The effect of lubrication and machine rigidity (in our case an industrial robot) has been analysed. Finally, we pointed out the apparition of vibration when two aluminium plates are drilled together. The behaviour is very variable and different steps of the drilling have to be considered: the drill entry in the aluminium part, the drilling, the drill exit from the plate and the drill backward movement. This allows for a particular value of drill diameter and drill overhang to determine the optimised feed rate and rotation frequency in order to achieve the best quality of the hole surface.

Effect of Cavitation of Cutting Fluid in Micro Drilling (1st Report)

Ultrasonic vibration has been applied on micro drilling of hard and brittle materials such as single crystalline silicon and glass etc. and has leaded to superior results. These methods proposed so far, however, need the special equipments to vibrate tool or workpiece. This paper proposes a new ultrasonic vibration method that vibrated the cutting fluid in which tool and workpiece are soaked. This principal is to accelerate the flow of chips by the cavitation generated in the fluid. Micro drilling of SUS304 and aluminum alloy is taken up and the drilling performance is discussed. In addition, the behavior of cavitation is observed with a high-speed camera in drilling of acrylic resin. The obtained results are as follows. Compared with conventional drilling, this method reduces adhesion and/or welding of chip owing to the cavitation generated at the front of the drill and in consequence brings out longer tool life, more stable chip removal and smaller surface roughness. Furthermore, the cooling effect is also superior in various coolant methods.

An experimental investigation of the effect of coatings and cutting parameters on the dry drilling performance of aluminium alloys

As a result of the need to automate assembly in the aircraft industry, along with economic and ecological reasons, industry and research institutions have been pushed to develop dry drilling for aluminium alloys to eliminate the need for cooling fluids. The main difficulties in dry drilling are accelerated tool wear due to workpiece material adhesion on the tool and the formation of bigger-sized burrs. This paper describes an experimental research study on machinability in the dry drilling of aluminium alloys and on the potential of the new design of tools and coatings. Dry drilling tests were performed using uncoated drills and two different coatings produced by means of an arc evaporation PVD process. Experiments consisted of machining with a 10-mm diameter three-edged drill to produce 25-mm deep holes. Tool wear evolution and burr size were analysed, as well as the impact of the process parameters on torque, power, feed force and tool temperature.

Effect of machining parameters and coating on wear mechanisms in dry drilling of aluminium alloys

The temperature generated by friction and plastic deformation in the secondary shear zone strongly controls tool wear. At lower cutting speeds tool wear is not severe insofar as the temperature is not significant. When the cutting speed is increased, there is a transition in wear mechanisms from abrasion and/or adhesion to diffusion. In the present paper, the change in wear mechanisms as a function of cutting speed and coating material is discussed. The cutting tests were performed on a rigid instrumented drilling bench without the use of cutting fluids. AA2024 aluminium alloy was used to investigate the wear mechanisms of cemented tungsten carbide and HSS tools. Three cutting speeds (25, 65 and 165 m/min) and a constant feed rate of 0.04 mm/rev were selected for the experiments. The best results in terms of maximum and minimum hole diameter deviations and surface roughness are obtained for the uncoated and coated tungsten carbide drills. The results also show that HSS tool is not suitable for dry machining of AA2024 aluminium alloy.

Application of grey-Taguchi method to optimise drilling of aluminium alloy 6061 with multiple performance characteristics

An approach to optimisation of the drilling of aluminium alloy 6061 with multiple performance characteristics, based on grey relational analysis associated with the Taguchi method, has been studied. Coated deposition, spindle speed and feed rate are optimised drilling parameters when the performance characteristics, which include tool life, surface roughness and burr height, are taken into consideration. Optimal drilling parameters for multiple performance characteristics have been derived. It is shown that the multiple performance characteristics are together improved by using this method.

Minimal lubrication machining of aluminium alloys

At present, there is a great deal of discussion about the use of lubricants in machining. Industry and research institutions are looking for ways to reduce the use of lubricants because of ecological and economical reasons. While there are established applications of dry turning and milling, dry drilling presents special difficulties due to the problems of swarf clearance from the drill flutes and consequent heat build-up and clogging. The rising costs associated with the use and disposal of cutting fluid have forced engineers to concern themselves more intensively with questions of cooling technology. Included in these concerns are topics such as cooling lubricant monitoring, cleaning and disposal together with exploring the potential for cooling lubricant reduction and avoidance. This paper presents an investigation into various methods of cutting fluid application with the objective of deriving the optimum cutting condition for the drilling of cast aluminium alloys. A series of tests were carried out using various methods of cutting fluid application, under varying conditions of cutting speed and feed.

410 アルミニウム合金のドライ穴あけに関する研究 : ドライ穴あけにおける切りくず生成

The purpose of this study is to achieve dry drilling of aluminum alloy. The aluminum alloy is higher adhesive than other metals. Therefore the dry drilling of aluminum alloy is difficult to generate flow type chip and smooth eject chip from drill flute in deep hole. But these are the most important factors in dry drilling of aluminum alloy. Therefore this study was carried on to investigate the relation between cutting fluid, helix angle and chip form, chip ejection. As a result of this study, it was realized that; 1) The chip of dry drilling is tear type. 2) The helix angle does not function in dry drilling in deep hole.

High Feed Rate Drilling of Aluminum Alloy

With the prime objective of contriving an effective method of drilling on conventional machine tools with conventional drills, the high feed rate drilling of aluminum alloy A1050, A2017 and A6061 is attempted with titanium nitride coated SKH56 drills under cutting conditions (1500rpm, 1.0mm/rev) harsher than those generally employed. Results obtained of cutting characteristics such as cutting forces, drill wear, heat generated, chip shape hole finish etc were examined in order to determine the critical cutting condition for conventional drills. From results obtained it is found that the high feed drilling of aluminum alloy A1050 is difficult practically. While high feed drilling in A2017 and A6061 alloys is very feasible.

Chip morphology and hole surface texture in the drilling of cast Aluminum alloys

The effects of cutting fluid and other process variables on chip morphology when drilling cast aluminium alloys are investigated. The effects of workpiece material, speed, feed, hole depth, cutting-fluid presence and percentage oil concentration, workpiece temperature, drill type and drill overhang are studied using statistically-designed experiments. The measured responses of the experiments are the size and the shape of the generated chips. The effect of chip size on hole surface finish is also examined. The results show that the significant variables affecting chip size include the feed, material, drill type and to a lesser extent, cutting-fluid presence and drill speed. The drilled hole surface is shown to be correlated to chip size.

Effects of cutting conditions on drilling of aluminum 380

The major purpose of this project was to determine the effects of cutting conditions on drilling of aluminum alloy 380. Measurements of tool wear and surface finish were taken for two cutting speeds and feed rates, respectively. In each of the four tests, a high-helix, high-speed steel drill, 1/4 in. (6.35 mm) in diameter, was used to produce 460 holes 1.00 in. (25.4 mm) deep. The speeds used were 195 and 390 ftJmin (99 and 198 cmJs), and the feeds were 0.016 and 0.032 in.Jrev (0.406 and 0.812 mmJrev). Cutting speed had a greater influence on tool wear than feed rate. However, mean surface roughness increased approximately the same amount when the speed was doubled, as it did when the feed rate was doubled.

Fatigue behaviour of steels with multiple notches. II. The effect of interaction between notches on the characteristics of plane bending fatigue: Wakahara, M., Kawagoishi, N. and Suenaga, K. Res. Rep. Fac. Eng., Kagoshima Univ. Nov. 1988 (30), 207–214 (in Japanese)

In recent years, aluminum alloy drill pipe are used more and more frequently in the exploration and development of the deep wells, ultra-deep wells and sour gas wells due to the high strength, light weight and corrosion resistance to H2S and CO2. However, the pitting and fracture failure sometimes occurred, resulting in giant economic losses and fatal disaster. In this study, the failure analysis of aluminum alloy drill pipe was addressed and the formation cause of the pits and parallel transvers cracks was investigated. Results show that the chemical composition and the regular mechanical properties (including tensile and impact properties) meet ISO 15546:2011 standard requirements. But the tensile strength of samples immersed in the mud environment is lower than that of ISO 15546:2011 standard requirements. Metallographic analysis results show intermittent ribbon Al6(MnFe) solid solution, S (CuMgAl2) phase and AlFeSi phase distributed on α solid solution. The failure cause of aluminum alloy drill pipe is mainly attributed to the brittleness sensitivity of intermittent banded second phase and inclusions to corrosive media from mud environment. Cracks and pits are prone to generate here. XRD and EDS analysis results of corrosion products and the pits bottom show that the main corrosion products are Al2O3, Al2S3, AlPO4, BaSO4 and CaCl5. S and Cl are from environment media. The microscopic morphology analysis results of the tensile and impact specimens fracture show that the fracture is the brittle fracture caused by the environmental medium.

On the effect of cutting fluid on drilling aluminum alloy

Several sorts of cutting fluids having various viscosities were used in drilling of aluminum alloys and their effects on drilling resistance, drilling temperature, drilling accuracy, state of drilled surface, disposal of chips, etc. were discussed. Since the reproducibility in supplying the fluid was not reliable, the drilling tests were conducted by dipping the whole specimen in the fluid. The results were summarized as follows.Nose angle of 118° and lip clearance of 12° were effective in drilling of aluminum alloys with cutting fluids when the effects on drilling temperature and roughness of drilled surface were taken into consideration. Among some kinds of drilling resistance, the viscosity of the liquid had little effects on torque; but the effects on thrust and drilling time were more powerful than those in dry drilling. (These values were higher than those in dry drilling). However, high viscous fluids were more effective, because they gave the lower values than those in dry drilling. When cutting speed was low, the drilling temperature was lower than that in dry drilling. The roughness of drilled surface was finished better than that in dry drilling, and also better effects were given on the disposal of chips, appearance of burrs at the outlet of hole, etc. However, no remarkable effects were found on the enlargement of hole diameter.