Chip Evacuation Research Articles

Mathematical modeling and multiresponse optimization to reduce surface roughness and adhesion in Al 5083 H116 alloys used in ammunition propulsion actuators

PurposeThis study aims to obtain the lowest surface roughness (Ra) and drill bit adhesion values (AV) depending on the change in control factors (cutting speed-Vc, feed rate-f and drill bit-D) during drilling of the Al 5083 H116 alloy. Low roughness values increase the fatigue strength of the final part and affect tribological properties such as lubrication and friction. In the machining of ductile materials, the AV increases the Ra value and negatively affects the tool life.Design/methodology/approachDrilling tests were conducted using Taguchi L16 orthogonal array. The experimental measurement findings for Ra and AV were adjusted utilizing the Grey Relational Analysis (GRA), the Response Surface Method (RSM) and Artificial Neural Networks (ANN) to generate prediction values. SEM detected drill-tip adhesions and chip morphology and they were analyzed by EDX.FindingsRa and AV increased as the f increased. Vc affects AV; 86.04% f on Ra and 54.71% Vc on AV were the most effective control parameters. After optimizing Ra and AV using GRA, the f is the most effective control factor. Vc: 120 m/min, f: 0.025 mm/rev and D2 were optimal. ANN predicted with Ra 99.6% and AV 99.8% accurately. Mathematical models are obtained with RSM. The increase in f increased AV, which had a negative effect on Ra, whereas the increase in Vc decreased the adhesion tendency. With the D1 drill bit with the highest flute length, a relatively lower Ra was measured, as it facilitates chip evacuation. In addition, the high correlations of the mathematical models obtained indicate that the models can be used safely.Originality/valueThe novelty of this study is to determine the optimum drilling parameters with GRA and ANN for drilling the necessary holes for the assembly of ammunition wing propulsion systems, especially those produced with Al 5083 H116 alloy, with rivets and bolts.

A comparative study on drillability of Inconel 625 alloy fabricated by wire arc additive manufacturing

In recent years, the cost-effective wire arc additive manufacturing (WAAM) method is increasingly replacing traditional production methods for Ni-based superalloys. However, the effect of high heat input and elemental segregation in the WAAM method on machinability has not yet been adequately investigated. For this purpose, drilling of wrought and WAAM Inconel 625 samples with thermal (i.e., die-sinking micro-EDM and micro-EDM) and mechanical drilling techniques (i.e., orbital and conventional drilling) was investigated in this study. It was observed that thermal drilling methods formed a white layer with a thickness of 20-25 μm and 35-50 μm in the cross-section of wrought and WAAM specimens, respectively, while no white layer was formed in the mechanical methods. The average surface roughness of the inside hole, Ra, obtained in the conventional drilling process has improved by 46.15 %, 94.62 %, and 92.82 %, compared to the orbital, die-sinking, and micro-EDM methods, respectively. Because the drill cutting form and helix angle used in this method facilitated chip evacuation. The best surface roughness was obtained respectively by conventional (0.27–029), orbital (0.51–0.53), die-sinking (4.54–5.88), and micro-EDM drilling (3.54–4.25) methods. In addition, a larger kerf angle is obtained in the WAAM sample compared to the wrought one due to higher residual stress and higher dislocation density in the WAAM alloy. On the other hand, the higher hardness value of WAAM samples provided better surface quality in mechanical drilling methods than wrought material. An increase in surface hardness values up to 25 μm from the surface was detected due to the recast layer formed in thermal drilling methods and the strain hardening occurring on the surface in mechanical drilling methods.

Surface Topography Description of Threads Made with Turning on Inconel 718 Shafts

The technology of producing threads, especially in materials that are difficult to cut, is a rare subject of research and scientific publications. The requirements for the production of these elements apply not only to the geometry, but also to the quality of the surface obtained. This is particularly important in the aviation industry, where the durability of the threaded connection affects passenger safety. Due to the design of the thread, the quality of its surface is assessed visually in industrial practice. The authors of this study decided to examine the surface topography of external threads made by turning on Inconel 718 shafts in order to confirm the visual evaluation, as well as to investigate the influence of such factors as cutting speed, turning direction and type of profile. Three types of contours were cut for the research: triangular, trapezoidal symmetrical and trapezoidal asymmetrical. Turning of each was carried out twice at cutting speeds vc = 17 m/min and vc = 30 m/min. On each of the threads, the side surface of the profile made in the direction of the insert feed and the opposite surface were examined. The surface texture parameters Sa, Sq, Sp, Sv, Sz, Ssk and Sku were determined and compared. It was noticed that the thread surfaces show a tendency to irregular roughness, which was confirmed by the analysis of the Sku and Ssk coefficients. The sides of the contours made in the direction of the insert feed are characterized by a higher roughness in relation to the opposite sides, which may result from high cutting forces and difficulties with chip evacuation. With the cutting speed being considered, lower values of Sa and Sq were obtained for vc = 17 m/min, which differed from the visual assessment, proving its high subjectivity.

Analysis of the cutting fluid behavior with a modified micro single-lip deep hole drilling tool

Deep drilling with smallest diameters is used for applications such as automotive, aerospace and medicine. Especially difficult to cut materials require an efficient tool design to realize an economical production. Therefore, combined simulation methods are used in this paper to analyze the fluid behavior under consideration of the transient chip positions. To improve tool cooling by an improved cutting fluid flow, which supports chip removal also, both the cross-sectional area of the internal cooling channel and the outer and inner cutting edge angles were modified. With the modified model, cutting fluid velocity increased by 40% and chip evacuation by 60%. • Cutting fluid analysis by micro deep hole drilling with SPH/DEM and CFD. • Efficient fluid flow through modified angle of incidence and cutting edges. • Significant increasing of cooling efficiency and process favorable chips. • Utilization of the chip attack surfaces and increase of the fluid velocity. • Increase the process reliability when machining Inconel 718.

A novel low-pressure hybrid dry ice blasting system for improving the tribological and machining characteristics of AISI-52100 tool steel

Hybrid minimum quantity lubrication and compressed carbon dioxide (MQL + CO2) lubri-coolant can play a crucial role in advancing machinability as well as sustainability. However, it is also the fact that the high-pressure throttling of CO2 produces fog and hinders the low-pressure MQL mist to touch the cutting zone adequately. Therefore, a low-pressure novel hybrid MQL-dry ice blasting lubri-coolant technology is anticipated to improve the machinability by providing the cooling and lubrication simultaneously in milling AISI-52100. This low-pressure hybrid dry ice blasting not only reduces an abundance of smog to reduce the cutting zone visibility, but the dry ice grains also behave as carriers to bring MQL-mist to the cutting zone perfectly. In this proposed study, the surface roughness, residual stresses, cutting temperature, surface hardness, tool wear, and cutting forces are measured by varying the cutting speed (75-300 m/min) and feed per tooth (0.04–0.12 mm/z) under hybrid MQL-dry ice blasting lubri-cooling condition in milling AISI52100 tool steel. The results of this study highlighted that as the cutting speed raised from 100 m/min to 300 m/min, an increase in cutting temperature was 22 % at a constant feed per tooth of 0.08 mm/z. Similarly, the decrease in surface roughness was 42 %, tool life reduced to 57 %, surface hardness increased to 9 %, and across-the-feed surface hardness increased to 58 % by the increase of cutting speed from 75 to 300 m/min and constant feed per tooth of 0.08 mm/z. The proof-of-the-concept study showed the machinability advancement under hybrid lubri-cooling technology due to precise penetration of MQL mist and dry ice grains into the cutting zone in terms of ease in chip evacuation, excellent lubrication, and cutting heat dissipation by sublimation of dry ice.

Testing of wear properties of inserts made from semi-solid processed experimental steel

To reduce the cost of manufacturing tools, which are commonly made from powder steels, high-alloy tool steel in the form of an ingot was cast. Conventional casting allows better use of recycled materials and an overall reduction in material production costs. This experimental steel was then processed in a semi-solid state to remove the unsuitable casting structure and to obtain the desired functional properties. In the case of tools, it is primarily a sufficient toughness and abrasion resistance. To determine the wear resistance of the experimental steel, replaceable inserts for machining tests were made. The inserts were prepared by electro-erosive machining. During testing, the geometry of the insert was optimized to achieve good chip evacuation and other cutting properties. Wear was measured using a digital microscope and at the same time, the roughness of the workpiece was measured. For comparison, a powder steel insert of the corresponding chemical composition was also produced, which has the commercial title Böhler K390 Microclean. This steel was heat-treated according to the manufacturer's recommendations. By comparing the results obtained on experimental cast steel and commercially produced powder steel, it was found that cast steel processed by semi-solid technology achieves three times lower cutting-edge wear during machining than powder steel.

Coupled Eulerian–Lagrangian simulation and experimental investigation of indexable drilling

In many industries, indexable insert drills are used to cost effectively produce short holes. However, common problems such as chatter vibrations, premature tool wear and generation of long curly chips that cause poor chip evacuation make optimization of the drilling process challenging and time-consuming. Therefore, robust predictive models of indexable drilling processes are desirable to support the development towards improved tool designs, enhanced cutting processes and increased productivity. This paper presents 3D finite element simulations of indexable drilling of AISI4140 workpieces. The Coupled Eulerian–Lagrangian framework is employed, and the focus is to predict the drilling torque, thrust force, temperature distributions and chip geometries. To reduce the computational effort, the cutting process is modelled separately for the peripheral and the central inserts. The total thrust force and torque are predicted by superposing the predicted result for each insert. Experiments and simulations are conducted at a constant rotational velocity of 2400 rpm and feed rates of 0.13, 0.16 and 0.18 mm/rev. While the predicted torques are in excellent agreement, the thrust forces showed discrepancies of 12 - 20% to the experimental measured data. Effects of the friction modelling on the predicted torque and thrust force are outlined, and possible reasons for the thrust force discrepancies are discussed in the paper. Additionally, the simulations indicate that the tool, chip and the local workpiece temperature distributions are virtually unaffected by the feed rate.

Effect of chamfer width and chamfer angle on tool wear in slot milling

The tool geometry is generally of great significance in metal cutting performance. The response surface method was used to optimize chamfer geometry to achieve reliable and minimum tool wear in slot milling. Models were developed for edge chipping, rake wear, and flank wear. The adequacy of the models was verified using analysis of variance at a 95% confidence level. Each response was optimized individually, and the multiple responses were optimized simultaneously using the desirability function approach. The Monte Carlo simulation method was applied to tolerance analysis. All milling tests were conducted at dry conditions; the chamfer width and the chamfer angle varied between 0.1 and 0.3 mm, and 10 and 30°, respectively. Optimal chamfer geometry for minimizing chipping and rake wear was small chamfer width and chamfer angle. The flank wear reached the minimum value for the tool with 0.18 mm chamfer width and 10° chamfer angle. The obtained composite model predicted good edge strength and minimum overall wear when the chamfer was 0.1 mm wide at a 10° angle. Thermal cracks were observed on the tools. They were small on the edges with the finest and least negative chamfer but were more significant on the more negative and greater chamfer. A great chamfer width and chamfer angle also resulted in insufficient chip evacuation. The results show how the edge geometry affects the tool’s reliability and wear and may help manufacturers minimize tool cost and downtime.

Surface roughness assessment on hole drilled through the identification and clustering of relevant external and internal signal statistical features

Drilling is a continuous cutting process where two or more cutting edges remove the material, to obtain the desired feature. During the chip evacuation, it generally rubs against the generated surface. Thus, the roughness obtained differs from other machining processes such as turning or milling. Therefore, surface roughness can be different from the analytically expected one. In this research work, an analysis of the cutting conditions where a level of roughness is expected to meet specific requirements has been carried out. 600 holes were made with two different tool geometries on steel without modifying the cutting conditions. When analysing the surface generated, certain variability in the roughness profiles obtained can be observed. External signals to the machine tool were acquired with sensors (cutting forces, vibrations, and acoustic emissions) as well as internal signals (spindle power, spindle torque in the Z-axis, spindle current and positions, speeds, accelerations, and jerk of the tool tip in the three axes of the machine). The most representative statistical features of the signals regarding roughness were selected using correlation analysis. Besides that, the hierarchical clustering of statistical features of the external and internal signals of the process was compared with clusters obtained using roughness parameters. Results show that clusters appear using signals highly related to the roughness parameters obtained from the measured profiles, confirming a mapping between the acquired signals during the machining process and the roughness of the holes.

Numerical simulation and experimental study for ultrasonic vibration-assisted drilling of SiCp/AL6063.

Thrust force and metal chips are essential focuses in SiCp/AL6063 drilling operations. Compared with conventional drilling (CD), the ultrasonic vibration-assisted drilling (UVAD) has attractive advantages: for instance, short chips, small cutting forces, etc. However, the mechanism of UVAD is still inadequate, especially in the thrust force prediction model and numerical simulation. In this study, a mathematical prediction model considering the ultrasonic vibration of the drill is established to calculate the thrust force of UVAD. A 3D finite element model (FEM) for the thrust force and chip morphology analysis is subsequently researched based on ABAQUS software. Finally, experiments of CD and UVAD of SiCp/Al6063 are performed. The results show that when the feed rate reaches 151.6 mm/min, the thrust force of UVAD decreases to 66.1 N, and width of the chip decreases to 228 um. As a result, the errors of the mathematical prediction and 3D FEM model of UVAD are about 12.1 and 17.4% for the thrust force, and the errors of the CD and UVAD of SiCp/Al6063 are 3.5 and 11.4% for the chip width, respectively. Compared with the CD, UVAD could reduce the thrust force and improve chip evacuation effectively.

Investigation of the thermomechanical loads on the bore surface during single-lip deep hole drilling of steel components

The surface integrity of components is decisive for their fatigue strength and is significantly influenced by applied machining processes. Particularly in drilling, the used coolant strategy affects the process stability and the surface quality produced due to its contribution to chip evacuation and the cooling and lubricating effect of the cutting zone. In this article, different cooling lubrication strategies are investigated in single-lip deep hole drilling of quenched and tempered AISI 4140 steel with respect to their effects on occurring thermomechanical loads and the resulting surface integrity parameters. The results for drilling with cutting oil, water-based emulsion and minimum quantity lubrication (MQL) under varying cutting parameters are analyzed with a focus on their impact on the bores’ subsurface microstructure and resulting hardening generated in the bores’ subsurface.

A short review on cooling process using compressed cold air by vortex tube in machining

In machining hard surfaces the biggest challenge is the removal of heat produced during the machining operation and the lubrication required to reduce the frictional force at the machining zone. The present paper is divided into three sections. The first section describes the introduction concepts of heat removal along with different environmental conscious machining methods. The second section discusses about the compressed air cooling method by Ranque-Hilsch vortex tube and the popular theories related to the energy separation method in vortex tube. Finally, the third section discusses about various applications of compressed air-cooling method in machining with various materials along with different machining processes and comparison with other cooling methods. This paper concludes that the separation of fluid into cold and hot in vortex tube is due to several effects simultaneously and not a single theory is able to explain it completely. Cold air-cooling system is more environment friendly, decreases the cutting force, increases the tool life, increases the surface finish, eases the chip evacuation process, nonhazardous to operator and it has the ability to replace the traditional lubrication system and a more research is needed in this direction so that the device can be adopted in practical use in industry.

Design, development and test of a novel broach for long polypropylene tubes

Polymers are frequently used for a variety of applications in industry. One relevant field is plastic tubing. As plastic tubes are manufactured from thermoplastic material through hot-extrusion their dimensional accuracy is only moderate. Wherever high accuracy on tube diameters and roundness are required, the conventional production techniques reach their limits and more complex technologies are needed. Known approaches from metal machining are deep hole drilling and internal broaching. However, machining processes with chip removal on polymeric materials are not so common. Therefore, the authors studied cutting operations of polypropylene experimentally. Based on their findings they designed and built an internal broach for the machining of polypropylene tubes. Finally, the authors tested their developed broaching tool in a relevant industrial environment. The tool not only fulfills the dimensional machining requirements but also solves the present chip evacuation problem in a unique way. It enables free cutting through the whole operation and creates continuous straight chips with no need for chip breakers. Consequently, the timely cleaning step, required in traditional broaching, can be eliminated, which reduces the lead time significantly. Furthermore, the set of materials allows dry broaching. Coolant is not necessary. This leads to less waste, a cleaner production line, and avoids damage through aggressive liquids. Lastly, their design ensures that no loss of dimension occurs when resharpening the tool.

Comprehensive experimental investigation on drilling multi-material carbon fiber reinforced aluminium laminates

The amalgamation of metallic alloys and fiber-reinforced composites has helped Fiber Metal Laminates (FMLs) like Carbon fiber reinforced aluminum laminates (CARALL), and Glasslaminatealuminum-reinforced epoxy (GLARE) overcome the limitations of standalone metals and composites. As a result, they have found increasing applications in the aircraft and defense industries. Moreover, the inhomogeneous nature and poor machinability of the materials make hole drilling challenging. Therefore, to enhance drilling performance, the paper reports a systematic analysis of the effect of spindle speed and axial feed on key performance measures, including thrust force, machining temperature, surface roughness, hole size, burr size, and chip morphology. Experimental outcomes indicate a significant reduction in the thrust force while utilizing higher spindle speed (4000 rev/min) and lower axial feed (0.1 mm/rev), while the surface finishes improved under high feed conditions (0.4 mm/rev). The analysis revealed that machining temperature increased with the employment of higher spindle speed and lower axial feed. Higher spindle speeds and axial feeds are desirable from the perspective of hole accuracy as they help produce holes within H9 diameter tolerance. Burr size was verified to be larger at the hole exit compared to the hole entry, with the size of the burr increasing with an increase in spindle speed and axial feed. The results show that the axial feed was the significant variable affecting chip size, followed by spindle speed. Higher axial feed (0.4 mm/rev) and spindle speed (4000 rev/min) helped improve the chip breakability, thus helping improve chip evacuation.

Cutting-fluid flow with chip evacuation during deep-hole drilling with twist drills

In this study the important aspects of cutting fluid distribution and the chip evacuation during micro twist deep-hole drilling are investigated using 3D multi-physics simulation methods. A coupled particle simulation is performed to analyze the chip transport by combining Smoothed Particle Hydrodynamics and the Discrete Element Method. Therefore, the transient transport of the chips is compared to a simulation scenario without chips. The coupled particle approach is capable to deal with free surfaces and fluid–solid interactions, that are subject to major topological changes over time. The chip positions resulting from the coupled particle simulation are used to carry out a Computational Fluid Dynamics simulation which considers the physical boundary conditions of the fluid and the process parameters to perform in-depth flow analyses. The results show good qualitative agreement between both simulation methods. Furthermore, the results show that large dead-zones with no fluid or almost zero fluid velocity exist in the flutes and that the chips there only experience a small evacuation force from the cutting fluid. The presented coupled approach of combining CFD and SPH–DEM simulation provide a significant support for future investigations to research the chip transport and to improve the tools and the process further.

Novel micro-deep-hole drill with variable web thickness and flute width

This study proposes a novel micro-deep-hole drill with variable web thickness and flute width to effectively improve the problem of tool breakage and chip clogging during micro-deep-hole drilling. Firstly, the failure form and failure mechanism of micro-drill are explored by performing drilling experiments, and it is found that the torsion fracture and bending fracture are the main premature failure modes of micro-deep-hole drilling tools. The static simulation analysis of micro-drill is further conducted to investigate the influence of geometric parameters on the stiffness and strength of high-aspect-ratio micro-drill, and the results indicate that the web thickness ratio and flute width have significant effects on drill tip stiffness and spiral groove root strength. To balance the rigidity, strength and chip evacuation capability of micro-deep-hole drilling tools, the new micro-drill with variable web thickness and flute width is developed, supplemented by comparative experiments. The results confirm that the new micro-drill has better chip removal ability, greatly reduces the drilling force, torque, drill tip wear and material peeling phenomenon, and significantly enhances the machining quality of hole wall.

Shrinkage Factor Analysis in the Dry Machining of UNS A92024 Alloy by FEM

Chip evacuation becomes a relevant factor in the dry machining of aeronautical aluminium alloys, either when they are machined as isotropic material or hybridized with other materials. Chip morphology and geometry highly depend on cutting parameters. Several works can be found in the literature focusing on the analysis of chip morphology of aluminium alloys at high cutting speeds but there is a lack of studies that apply low cutting speeds. FEM simulation may be useful to reduce the experimental time and cost of this kind of analysis. Therefore, in this work, the influence of feed-rate on several chip geometrical parameters (height of peaks, height of valleys and shrinkage factor) of dry turned UNS A92024 alloy has been analysed by FEM simulation. Three different energy fracture modes have been tested as damage evolution criterion, in order to get the mode that better fit the experimental chip morphology. In general, the mixed mode was the fracture energy mode that best suited the chip morphology behaviour, within wider feed-rate range.

Friction - wear modeling in drilling process of H-13 tool steel

Simulation of metal cutting is complex both from numerical and physical perspective. The scope of this work is to elaborate on the process and physics of metal cutting, and more specifically drilling. The description of H-13 steel dry drilling with the use of a single-layer TiN coated carbide twist drill is presented. H-13 is a high strength alloy steel used in demanding applications and elevated temperatures. A simulation model was developed with use of Deform-3D software, and an experiment was conducted in order to evaluate the acquired simulation results, meaning the wear mechanisms and thermal loads implemented during the process of drilling. The Usui wear model was used for the calculation of the wear rate of the drill. Regarding the experiment, a thermal camera was used in order to record the temperature of the drill after the process. The comparative analysis of the simulation models and the experiment showed that adhesion is the dominant wear mechanism. Higher wear values were observed in the rake faces of the drill, where the coating starts to fade, due to built-up edges (BUE). The tool and workpiece temperatures reach near steady state conditions during process. Elevated temperatures are applied on the removed material. Good chip evacuation and chip length indicate that coated drills with optimized geometry are suitable for drilling tough materials.

Experimental and FEM analysis of dry and cryogenic turning of hardened steel 100Cr6 using CBN Wiper tools

Employing cutting fluids in machining processes, especially for difficult-to-cut materials, improves machinability through prolonged tool life, improves surface integrity and chip evacuation. However, like oil and water-based cutting fluids are hazardous to the environment and workers’ health, alternative solutions are required. Liquid Nitrogen (LN2) is a cryogenic fluid that can be an option due to its low boiling point (-197ºC) and the fact it exists in the atmosphere at room conditions. Nevertheless, the feasibility of cryogenic cooling techniques in machining is not fully understood; this is why the Finite Element Method (FEM) could give an insight into the phenomena happening on the tool-chip/workpiece interface. This research aims to compare fundamental and industrial outputs when turning hardened steel 100Cr6 using Cubic Boron Nitride (CBN) inserts with wiper geometry in dry conditions and with cryogenic cooling. For this purpose, turning experimental tests were performed in both cooling conditions varying the cutting speed (150-550 m/min). Machining forces were measured during the tests, and then tool wear, microstructural damage, and residual stresses of the workpiece were characterised. A nose turning (3D) FEM model was also developed to understand the influence of cooling strategy on the outputs measured experimentally.

Effect of ultrasonic vibration on the performance of deep hole drilling process

Deep hole drilling process is extensively used in demanding applications, namely plastic injection moulding, oil and gas industry and automobile engines. This drilling process encounters problems such as improper chip evacuation, poor surface finish, roundness variation, and high tool wear, which affects the hole quality. To overcome these limitations, ultrasonic vibration-assisted deep hole drilling (UVADD) is performed in this work. The high-frequency vibrations were imparted into the ASTM A36 steel (workpiece) to induce reciprocating motion, which is mounted over a transducer. A special fixture arrangement was fabricated to hold the transducer in the drill bed. This helps to transfer the vibration to the workpiece. The machining performance of UVADD was analyzed by means of cutting force, tool wear, torque, hole quality, surface roughness, machining time and chip morphology, and the performances were also compared with the conventional deep hole drilling (CDD) process. Results suggested that a reduction in cutting force and torque was observed for UVADD. This is due to small discontinuous chips generated. Hole quality showed a drastic decrease in burr formation and surface roughness along with a uniform radius around the periphery. From the tool wear examination, it was also evident that no built-up edge formation occurred along the cutting edge owing to effective penetration of coolant and reduction in cutting temperature. This comprehensive analysis revealed that UVADD provided an enhancement in machining performance as compared to CDD.