Feed Angle Research Articles

New tool concept for grinding a plateau-like surface for tribological applications

One of the most important factors for energy efficiency is the reduction of friction in machine elements. The grinding process is often the final machining process in machining hardened steel parts and the resulting surface finish influences the tribological behavior. The combination of grinding with a honing process can generate a plateau-like surface to reduce friction and create an oil reservoir to decrease abrasive wear and improve the fluid film stability. Additional processes like laser machining, micro milling or etching are able to generate micro dimples to improve the reduction of friction. Today, grinding processes are limited to machine plateau-like surfaces. Within this paper, a new tool concept will be presented, composed of a grinding tool with two different grain sizes and a metallic bonding. The use of small abrasive grains generates a smooth surface with low roughness values. A few additional larger grains induce stochastic scratches and create the plateau-like surface. Grinding experiments are conducted to analyze the effect of feed rate, feed angle and ratio between small and large grains on the resulting surface.

Numerical evaluation of heat transfer and NOx emissions under deep-air-staging conditions within a 600 MWe tangentially fired pulverized-coal boiler

Numerical evaluation of heat transfer and NOx emissions was conducted within a 600MWe tangentially fired pulverized-coal boiler configured with the deep-air-staging combustion technology, composing of concentric horizontal bias staged-air (CFS) burners and opposing tangential separated over-fire air (SOFA) burners. Refined char burning model considering gasification reactions and NOx model were implemented and validated with on-site measurement. Bell-shaped heat flux distributions with peaks severely deviating from the furnace center line appeared in the primary combustion zone, while heat flux distribution was uniform in the burnout zone. The results revealed that the larger the feed angle of CFS air, the more uniform the heat flux distribution with lower heat flux peaks. Concurrently, NOx emissions decreased by 12% from 250 to 220mg/m3 at 6% O2 and the optimum value occurred with CFS injection angle fixed at 15°. When the SOFA ratio was increased from 10% to 40%, distinct NOx reduction (levels from 358 to 174mg/m3 at 6% O2) associated with more uniform heat flux distributions was achieved. Owing to the intense turbulence mixing of the opposing tangential jets with the upward flow, saddle-shaped heat flux curves with slightly higher peaks appeared in the burnout zone as SOFA ratio was 40%.

Determining suitable dimensions for dairy goat feeding places by evaluating body posture and feeding reach

Confined goats spend a substantial part of the day feeding. A poorly designed feeding place increases the risk of feeding in nonphysiological body postures, and even injury. Scientifically validated information on suitable dimensions of feeding places for loose-housed goats is almost absent from the literature. The aim of the present study was, therefore, to determine feeding place dimensions that would allow goats to feed in a species-appropriate, relaxed body posture. A total of 27 goats with a height at the withers of 62 to 80 cm were included in the study. Goats were tested individually in an experimental feeding stall that allowed the height difference between the feed table, the standing area of the forelegs, and a feeding area step (difference in height between forelegs and hind legs) to be varied. The goats accessed the feed table via a palisade feeding barrier. The feed table was equipped with recesses at varying distances to the feeding barrier (5-55 cm in 5-cm steps) at angles of 30°, 60°, 90°, 120°, or 150° (feeding angle), which were filled with the goats' preferred food. In 18 trials, balanced for order across animals, each animal underwent all possible combinations of feeding area step (3 levels: 0, 10, and 20 cm) and of difference in height between feed table and standing area of forelegs (6 levels: 0, 5, 10, 15, 20, and 25 cm). The minimum and maximum reach at which the animals could reach feed on the table with a relaxed body posture was determined for each combination. Statistical analysis was performed using mixed-effects models. The animals were able to feed with a relaxed posture when the feed table was at least 10 cm higher than the standing height of the goats' forelegs. Larger goats achieved smaller minimum reaches and minimum reach increased if the goats' head and neck were angled. Maximum reach increased with increasing height at withers and height of the feed table. The presence of a feeding area step had no influence on minimum and maximum reach. Based on these results, the goats' feeding place can be designed to ensure that the animals are able to reach all of the feed in the manger or on the feed table with a relaxed posture, thus avoiding injuries and nonphysiological stress on joints and hooves. A feeding area step up to a maximum of 20 cm need not be taken into account in terms of feeding reach. However, the feed table must be raised at least 10 cm above the standing area to allow the goats to feed in a species-appropriate, relaxed posture.

Effect of modified drill point geometry on drilling quality characteristics of metal matrix composite (MMCs)

The abrasive reinforcement present in ‘Metal matrix composites’ (MMCs) is responsible for numerous machining challenges for the research fraternity. The increase in tool wear, burr formation, surface roughness, and increase in cutting forces are few of such machining challenges during the drilling of MMCs. The present research investigation explores the effect of change in drill point geometry on the drilling Quality characteristics (QCs) of the drilled hole wall. The drilling QCs under investigation are, Specific cutting pressure (SCP) and Surface roughness (SR) of the drilled hole wall. The levels of the input process parameters for optimum values of the output responses were established by Taguchi’s methodology. SEM images and contour plots of drilled hole wall have been used to qualitatively explain the drilling behavior of MMCs. The chip formation mechanism observed during drilling establishes the cutting behavior of the different cutting edges of the modified drill point geometry. It has been observed that the single conical chips were produced by primary cutting edge and single ring type chips were produced by secondary cutting edge. The step diameter is the main factor which influences the SCP followed by the feed and point angle. The surface roughness of the drilled hole wall has been governed by the cutting speed, feed and step diameter. Burnishing and honing effect were observed on the drilled hole wall surface because of entrapped free SiC particles using SEM.

Powder cloud behavior in laser cladding using scanning optics

Powder feeding is one of the single most important parameters that defines a qualitative outcome of the cladding process. This study focuses on how powder feeding angle and powder carrying gas flow rate affect the powder cloud behavior in laser cladding with scanning optics. Focus of this study is to provide the knowledge on how scanned laser beam affects the powder cloud and what kind of phenomena can occur during cladding process. In this study, powder feeding angles from 40° to 70° were tested with powder feeding gas flow rates of 3 and 6 l/min and with laser scanning frequencies ranging from 80 to 150 Hz. Powder material used was 316L, and the substrate material was low alloyed steel. The results showed that the stability of the powder cloud was highly dependent on the tested parameters. At a steep powder feeding angle, the powder cloud under laser radiation was strongly vaporized, emitting bright visible light. However, at gently sloping powder feeding angle, the powder cloud behavior was more stable; i.e., less or no vaporization was noticed, and the emitted light was fainter. Also, a direct correlation between the vaporization of the powder cloud and the increase of dilution was noticed. It was determined to be a cause of vapor flow disturbing the powder feeding into the melt pool and thereby increasing dilution.

와이어 송급 레이저 금속 3차원 적층 연구동향

Recent developments of Laser metal 3D deposition with wire feeding are reviewed which provide an alternative to powder feeding method. The wire feeding direction, angle and position as well as laser power, wire feeding rate, and deposition speed are found to be key parameters to make quality deposition with high throughput. When compared with the powder feed, the wire feed shows higher material efficiency, higher deposition rate, and smoother surface. Large elongated columnar grains which have epitaxial growth across deposit layers are observed in deposit cross sections. The growth direction is parallel to the thermal gradient during the deposit process. Tensile properties are found to be dependent on the direction due to the anisotropic deposit property. A real-time feedback control is demonstrated to be effective to improve the deposition stability. Key words: Wire feeding, Laser, Metal deposition, Microstructure, Mechanical properties, Feedback control

Orthogonal cutting of TA6V alloys with chamfered tools: Analysis of tool–chip contact lengths

In aerospace industry, the materials constituting aircraft evolved considerably in recent decades. The choice of composite materials (carbon fiber–reinforced plastic or multi-material) reduces the weight of structures, but for critical parts that support important forces or temperature, the indicated materials are alloys based on nickel or titanium. Consumption of titanium for the aerospace industry is growing rapidly, and the new generations of aircraft show an increase in the percentage of titanium. The TA6V is mostly used for structural parts, especially for engine pylon. Due to its low thermal properties, it shows a poor machinability, leading tools to undergo severe wears. The aim of this work is to understand the relation between cutting conditions and chamfered tool geometries on chip formation and tool wear. Based on a model dedicated to the understanding of cutting process with chamfered tool and on experimental tests, this work will show the influence of feed, cutting speed, chamfer length and rake angle on tool–chip contact lengths. It will also show the influence of these parameters on the variability of these contacts within a same geometry or cutting condition. This will lead to another interpretation of tool wears and pressures on the rake face.

Определение настроечных параметров процесса прошивки на двухвалковых станах винтовой прокатки

Mathematical dependences for the description of basic geometric parameters of the deformation zone with a screw insertion on two-roll mills were developed. The obtained expressions take into account the distortion of the roll gap caused by the rotation of the piercer rolls to a feed angle at any cross section and can be used for the mathematical description of twin screw rolling mills with mushroom and barrel rolls operating at higher filing angles. For a sufficiently precise mathematical description of the geometric parameters of the deformation zone dependencies were proposed that allow to determine the distance from the rolling axis to the roll surface at any cross section of the deformation zone. The distance from the rolling axis to the roll surface was defined on the assumption that the radius of the roll on its main meridional plane is negligible. The comparison of obtained mathematical relationships with solid modeling, based on surface modeling with boundary representation of solids and implemented in the SAD programme Compass-3D showed good convergence and legitimacy of the accepted assumption. On the basis of expressions obtained a method to determine main parameters of the process of tuning screw firmware was developed, i.e. the distance between the rollers in a roll pinch; mandrel extension outside rolls’ survivors; compression in front of the mandrel toe, and the distance from the workpiece grip of the roll to the mandrel toe. The developed mathematical relationships are also suitable for the development of the rolling tool calibration of piercing mills (mandrels and rolls) and for the analysis according to the deformation scheme during the screw insertion process.

Nonlinear optimization of gravity solids classification based on the feed and deck angles: a law of mass action approach

Deck screen design parameters e.g. material of construction, deck angle of inclination, the feed throughputs, and physicochemical properties of the particles, are critical factors to consider in solids classification. Two significant and easily manipulated parameters that greatly affect screen performance are the feed rate and design geometry configuration. In this work we apply statistical analysis of variance (ANOVA) and nonlinear least squares optimization with parameter estimation concepts, first, to assess the significance of the two factors and, second to formulate flow prediction models that optimize the feed rate and classification efficiency. Experiments were conducted on a prototype screen of 556.28cm2 effective area, (1380cm2 total area). For glass beads of sizes 0.75, 1, 2, and 3mm, with 16 feed batches of 10g to 160g, and six inclination angles 5, 10, 12.5, 15, 17.5, and 20°, a maximum efficiency of 66.7% was achieved with a screen loading of 86.5g, and an inclination angle of 17.5°. These results were then subjected to nonlinear least squares optimization, which showed that a maximum efficiency of 93.2% can be achieved at batch loading as low as 36g. There was a favorable performance at the range of angles 12.5≤θ≤17.5°, but poor performance outside this range. The screening efficiency did not respond significantly to changes in screen loading, although loading had a significant effect on the screening capacity. Confirmation tests conducted at selected optimum parameters achieved a maximum efficiency of 72% (at 12.5° with 49.6g batch load), and a maximum rate of 27g/s at 17.5° with 104g.

Experimental and numerical study on formation mechanism of linear macro-segregation in low-pressure die casting of Al–Cu–Mn–Ti Alloy

The formation mechanism of linear macro-segregation in Al–Cu–Mn–Ti alloy cylindrical shell casting was studied by characterizing samples by X-ray detection, microscopic examinations, composition analysis, and simulation of the heat transfer of Al–Cu–Mn–Ti alloy cylindrical shell casting in the solidification process. Numerical and experimental results indicated that linear macro-segregation always occurred in the portion of casting connected with the slit gating system, because of the great hot tearing tendency, the hot cracks formed could be fed by the melt through the slit gating system with an excellent temperature gradient and feeding angle. According to significant effect of floatation of lower density α-Al grains, the solute gradient was formed along the vertical direction of the slit gating system. The hot cracks near the bottom of casting were fed by melt with high concentration of Cu and so, they were cicatrized by the eutectic structure/α-Al + Al2Cu at a temperature of 548℃.

두 단락 스터브를 갖는 이중 모드 링 공진기를 이용한 WLAN용 이중대역 대역통과 여파기의 설계 및 제작

본 논문에서는 두 단락 스터브를 갖는 이중 모드 링 공진기를 이용하여 높은 신호 선택도를 가지는 이중대역 대역통과 필터를 제안하였다. 링 공진기의 이중 모드 공진을 위하여 두 피드 라인을 커플링 커패시터를 통해 비직교 급전 각도를 가지도록 연결하였다. 서로 다른 두 길이를 가지는 두 단락 스터브를 링 공진기의 두 대칭면에 위치시킴으로써 이중 대역을 지원하는 여파기를 설계할 수 있었다. 급전 각도 섭동을 준 링 공진기와 제안한 이중대역 대역통과 필터는 대칭 구조이므로 Even/Odd 모드 해석을 통하여 산란계수와 전송 영점 주파수들을 도출할 수 있다. 제안한 이중대역 대역통과 필터는 IEEE 802.11n 기준의 WLAN 어플리케이션에 적용 가능하도록 설계 및 제작되었다. 측정 결과와 시뮬레이션 결과가 잘 부합하였고, WLAN 응용뿐만 아니라, 향후 다른 통신시스템에도 적용이 가능하리라 판단된다. In this paper, A high selective dual-band bandpass filter was proposed using a dual-mode ring resonator with two short-circuited stubs. For dual-mode resonance, the ring resonator is directly connected with non-orthogonal feed-lines via coupling capacitors. Two short-circuited stubs which are unequal lengths are simultaneously placed at two corners along the two symmetry plane of the ring resonator in order to obtain dual-band responses. Because the feeding angle perturbated ring resonator of the proposed dual-band bandpass filter has the symmetrical structure, Even/Odd mode analysis can be well applied to extract the scattering parameters and transmission zero frequencies. The proposed dual-band bandpass filter was designed and fabricated for WLAN(Wireless Local Area Network) application of IEEE 802.11n standard. The measured results showed a good agreement with the simulation results, and it should be well applied not only for WLAN applications but also for any other communication systems.

Modeling of friction along the tool-chip interface in Ti6Al4V alloy cutting

The aim of the paper is the modeling of chip formation in metal cutting in order to describe the thermomechanical interactions at the tool-chip interface (TCI). A particular attention is paid for the fully sticking case to complete previous modeling works which were more focused on the sliding regime or mixed sliding/sticking regime. The fully sticking contact is dominating due to the combined effects of high magnitudes of the normal stress, the average friction coefficient \( \left(\overline{\upmu}\to 1\right) \) and the temperature. This case is also well adapted for cutting of titanium alloy. In the present model, these local parameters are macroscopically expressed through the average friction coefficient \( \overline{\upmu} \), and the velocity field on the secondary shear zone is modeled using a new approach. The ratio between real area of contact A r and the apparent area A n is taken into consideration. The developed approach is also fully thermomechanically coupled with heat transfer consideration. In this way, it was possible to predict normal and shear stress according to the variation of cutting velocities, feed and rake angle. The model was supported by the experimental trends from Ti6Al4V alloy cutting tests and worn tools analysis. It was shown that the distribution of the ratio A r /A n may be considered as a good indicator to describe the spreading of the adhesion marks on the contact. The model also highlights how the influence of the apparent friction coefficient, the rake angle, the feed and the cutting speed acts on the tool-chip contact length.

Mechanical Characterization and Machinability Behavior of Annealed AISI D6 Cold Working Steel

Tool steels in metal forming industry are exposed to complex and aggressive conditions due to multiple effects (mechanical, thermal, or tribological loading) and require defined mechanical properties. Also machining of tool steel with poor machinability like AISI D6 to manufacture form tools is an extremely difficult task. This paper investigates the microstructural, mechanical, and machining behavior of AISI D6 steel in annealed and hardened conditions. Various mechanical tests indicated good hardenability, improved surface hardness, and phenomenal improvement in tensile strength but extremely poor resistance to impact in both annealed and hardened condition for this steel. The machining characteristics of AISI D6 steel were evaluated using a 2k unreplicated full factorial design approach and statistical techniques have been used to assess and identify the significant factors, namely, cutting speed, feed, depth of cut, and approach angle, in minimizing surface roughness and main cutting force while machining this steel with a carbide tool. It was found that the depth of cut, feed, and approach angle are the most significant factors affecting the surface roughness and depth of cut and feed affect the main cutting force. Cutting speed has no effect on surface roughness and main cutting force in machining of the steel in annealed condition.

Some studies on drilling of red mud reinforced aluminum composite

Ceramics reinforced aluminum metal matrix composites are mostly used in automobile, aerospace, and its related industries because of its superior mechanical and tribological properties. In the present work, the drilling studies of LM25 aluminum-based composite is selected to carry out the experiments. Novel industrial waste red mud particles are used as the reinforcement material, which can reduce the environmental hazards and the problem of disposing. The effect of three input factors such as speed, feed, and point angle over the output response such as surface roughness, vibration, and power consumption are studied using L27 orthogonal array. The optimal factor settings for each output performance are determined by employing the Taguchi method. Further, the analysis of variance is also performed for each parameter to know the significant contribution. However, in order to minimize the responses simultaneously, multi-objective optimization by ratio analysis based entropy method is adopted and the optimum levels of the drilling process are found. When the optimum parametric setting is used, the surface roughness is reduced by 13.63%, power consumption by 9.1%, and vibration by 15.14%.

Improving electrical conductivity of poly methyl methacrylate by utilization of carbon nanotube and CO2 laser

ABSTRACTIn this work, the electrical surface conductivity enhancement of injection‐molded multiwalled carbon nanotube (MWCNT)/poly(methyl methacrylate) (PMMA) nanocomposite by using CO2 laser processing was studied. Variable input factors are considered as MWCNT concentration (in three levels 0.5, 1, and 1.5 wt %), the laser feed angle with the flow direction (in five levels 0°, 30°, 45°, 75°, and 90°), and the cavity machining method that were produced by electrodischarge machining and computer numerical control milling with finishing process. The studies show that the irradiation of laser and utilization of covering gas could enhance the CNT–CNT contacts and the surface electrical conductivity. The morphology of laser‐irradiated surface by using scanning electron microscope certified that the conductive network generated from CNT–CNT contacts can transfer the electrical current. The findings clearly show that the laser feed angle with the flow direction influenced the electrical conductivity. The maximum conductivity (∼ 5.310 × 10−4 S) was observed at 75°. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42671.

A mathematical model and numerical investigation for glycerol gasification in supercritical water with a tubular reactor

This paper developed a three-dimensional computational fluid dynamics model of the supercritical water gasification (SCWG) process of glycerol. The detailed flow field, temperature field and chemical species distributions inside the reactor were revealed, and the effects of the operating parameters on the results in the SCWG of glycerol were investigated. The reasons for incomplete gasification were discussed, and relevant possible improvements were proposed. (1) The residence time is not long enough for the complete gasification; therefore, the optimal length of the tubular reactor was obtained under different operating conditions. (2) A side-reaction region was formed near the feeding inlet and methods to reduce the volume of the side-reaction region were investigated. A high preheated water temperature and a 135° feeding angle were proved to obviously avoid side-reaction. A multi-injection feeding method can also suppress the side-reaction, but the carbon gasification efficiency decreased.

Investigations on Drilling of Bidirectional Cotton Polyester Composite

Cotton fiber composites are currently used in the interior parts of automobiles, insulation boards, fiber boards, and various parts of high-friction mechanical assemblies. These composites are subjected to machining operations. Drilling is an indispensable machining operation for assembly of different parts. The present work aimed to carry out experimental and analytical investigations on drilling of bidirectional cotton polyester composite. Influence of feed, spindle speed, and drill point angle on machining characteristics like thrust force, torque, and delamination factor was studied by conducting experiments derived from Taguchi's L27 orthogonal array. To determine the significance of each drilling process parameters and their interactions, analysis of variance (ANOVA) test was conducted. Modeling of drilling parameters was carried out through multiple regression analysis and their optimization for minimizing cutting forces and machining induced damage was carried out using signal to noise ratio analysis.

Forming mechanism of three-dimensional integral fin based on flat surface

To improve heat-transfer performance, a novel integral three-dimensional fin-structure on the plat surface was presented to increase the evaporation efficiency. The three-dimensional fin-structure is composed of a spiral micro-groove and multi radial micro-grooves. Both ploughing-extrusion (P-E) and stamping were used to form the integral-fins with a connection between radial and circumferential directions. Based on the SEM results, the relationships among P-E speed vP-E, rotational speed np and feed fp, and among interference length Li, stamping feed angle θc and stamping depth ac were analyzed. The effects of processing parameters on the groove morphology and the matching relationship between parameters were also discussed. The integral finned surface with micro-grooves and cracks can be obtained under such processing conditions: P-E depth ap=0.3 mm, ac=0.3 mm, the interval of helical groove dp=1.24 mm, θc=2° and np=50 r/min.

Study of High Speed Machining by Using Split Hopkinson Pressure Bar

The purpose of this paper is to study the effect of cutting parameters such as speed, feed and rake angle on the chip formation mechanism and the main cutting force by simulating an orthogonal cutting operation on a testing apparatus based on a split Hopkinson pressure bar. This device can produce two chips on either sides of the specimen. Cutting tests were carried out on four different materials at different speed feed and tool geometry. Microstructural observations of the chips produced show a change in the morphology of the chip in accordance with the increase of the cutting speed. The chip presents instabilities by adiabatic shearing, without any doubt. It changes from a continuous chip to indented one and to completely sheared off. The Appearance of shear band in the case of indented and completely sheared chip is probably due to strain localization accompanied by a large local growth of the temperature which is a necessary condition to have adiabatic shearing. This phenomenon might be desirable in reducing the level of the cutting forces and by improving chip's evacuation especially in automatic production of parts. Similar results are obtained by .[1] [2] [3] [4] [7]. Cutting force shows a decrease versus the cutting speed. This decrease is more important for larger feeds. The increase of the cutting angle from 5 to 15° also causes a reduction of the cutting force that evolves asymptotically. With high cutting speeds, the energy of plastic deformation in the primary zone of the chip formation is transformed mainly in heat which causes a thermal softening which outweighs the hardening generating therefore a reduction in the cutting force; these results are in accordance with those obtained by .[5] [7].

Studies on surface integrity and its optimisation in turning Ti-6Al-4V

The present work focus to assess desired machining parameters, speed, feed, depth-of-cut and rake angle for simultaneously optimising surface roughness and residual stresses induced during turning of Ti-6Al-4V with TiAlN coated tungsten carbide tools. Experiments have been conducted using L9 orthogonal array based design of experiments. The residual stresses induced in the workpiece after turning have been measured using X-ray diffraction system where as the roughness has been measured using portable surface roughness tester. The feed has been identified as the most significant parameter for the turning operation, according to the weighted sum grade of the residual stresses and surface roughness. From this investigation, it is suggested that for machining titanium alloy with TiAlN coated cutting tools, one should use the cutting speed at 75 m/min, feed at 0.25 mm/rev, depths-of-cut at 0.25 mm and a back rake angle at -7 degrees to achieve compressive or minimal tensile residual stresses and good surface finish.