Increasing Wheel Speed Research Articles

Microstructure and magnetocaloric properties in melt-spun and high-pressure hydrogenated La0.5Pr0.5Fe11.4Si1.6 ribbons* *Project supported by the National Natural Science Foundation of China (Grant No. 51771197), the Fund from the Chinese Academy of Sciences (Grant No. KJZD-EW-M05), and the Liaoning Revitalization Talents Program, China (Grant No. XLYC1807122).

The effects of wheel speeds and high-pressure hydrogen treatment on phase evolution, microstructure, and magnetocaloric properties in La0.5Pr0.5Fe11.4Si1.6 melt-spun ribbons are studied in this work. The results reveal that the increase of wheel speed is beneficial to the formation of cubic NaZn13-type phase and the grain refinement. The optimized wheel speed for microstructural and magnetocaloric properties is 30 m/s. The largest entropy change of 18.1 J/kg⋅K at 190 K under a magnetic field change of 0 T–5 T is obtained in La0.5Pr0.5Fe11.4Si1.6 ribbons melt-spun at 30 m/s. After a high-pressure hydrogen treatment of 50 MPa, the Curie temperature of the ribbons prepared at 30 m/s is adjusted to about 314 K and the large –ΔS M of 17.9 J/kg⋅K under a magnetic field change of 0 T–5 T is achieved at room temperature with almost none hysteresis loss. The small thermal and magnetic hysteresis and the large –ΔS M make the La0.5Pr0.5Fe11.4Si1.6 hydride ribbons appropriate for magnetic refrigerant applications around room temperature.

High speed super abrasive grinding of sintered yttria stabilised zirconia (YSZ) using single layer electroplated diamond grinding wheels

High speed moderate depth super-abrasive grinding of sintered yttria stabilized zirconia (YSZ) using coolant was done in current experiment. Electroplated diamond grinding wheels of 151 μm grit size having grits of grade PDA878 were used in the present studies. The diameters of the wheels used in high-speed grinding (up to 200 m/sec) were 125 mm, with a width of 10 mm. Grinding forces were measured. The grinding forces and specific grinding energies were very less compared to grinding of metals and metallic alloys because of the mechanism of ceramic grinding which is by micro brittle fracture, whereas the mechanism of grinding in metals and metallic alloys is by shear deformation. X-ray diffraction data of received and ground sample showed the various lattice plane belonging to Yttria stabilized zirconia (YSZ) and no phase change was observed before and after the grinding. At low depth of cut and table speed surface roughness decreases with increase in wheel speed. But at high depth of cut it is increasing in nature.

Investigation of three-body abrasive wear characteristics of white ark shell powder

Abstract In this work, white ark shell powder (a natural sea waste) was investigated for its abrasive character using dry abrasion tester with two other commercially available materials i.e., American Foundrymen’s Society (AFS) quartz sand and cashew nut shell liquid (CNSL) friction powder. A total of 54 experiments were performed on dry abrasion tester using these powdered materials against a grey cast iron (GCI) specimen at two different wheel speeds of 100 r.p.m. and 200 r.p.m. with varying wheel revolutions from 250 to 750 under the loads of 38 N, 51 N and 64 N. The particle size was kept in the range of 50–70B.S.S. mesh. It was observed that the volume loss of GCI specimen increased with increase in load and wheel revolutions at both the wheel speeds. The increase in wheel speed from 100 r.p.m. to 200 r.p.m. also influenced the volume loss significantly. The wear volume loss at all the combinations of wheel revolutions and wheel speed for the tested abrasives in decreasing order was observed as: AFS quartz > CNSL powder > white ark shell powder. The lower volume loss of counter surface against white ark shell powder suggests its use in such applications where low wear rate is required.

Fabrication of silicon carbide microchannels by thin diamond wheel grinding

Silicon carbide (SiC) microchannels are attractive for their wide applications in microsensors, MOS devices, UV photodiodes, microcatalytic reactors, and microchannel heat exchangers in harsh environments. However, the machining of SiC microchannels poses many challenges because of the difficulty and cost involved in the material removal process due to the high hardness and brittleness of SiC ceramic. In the present study, we developed a thin diamond wheel grinding process to fabricate SiC microchannels in a conventional vertical milling machine. Microchannels with trapezoidal shapes were successfully processed in SiC substrates by thin diamond wheels. The formation, geometric dimensions, and surface quality of SiC microchannels were studied together with the analysis of material removal mechanism. The effects of grinding processing parameters, i.e., wheel speed, feed speed, grinding depth, and grinding tool parameters including grit size and thickness of diamond grinding wheel, on the geometric dimension and surface morphology were comprehensively explored. The top width of microchannels first increased and then decreased with the increase in wheel speed, whereas a reverse tendency was observed with increasing grinding depth, feed speed, and grit size. The surface roughness decreased continuously with increasing wheel speed, but it tended to increase with the increase in feed speed generally. The variations in geometric dimensions and surface roughness of SiC microchannels can be related to the crack or fracture propagations and material removal mechanism during the thin diamond wheel grinding process. Besides, the influential significance of the above processing and grinding tool parameters were also evaluated by analysis of variance (ANOVA).

Effect of an elastic surface on snow and ice accumulation on vehicles

The ice on vehicles has increased the requirements of vehicular mobility, safety, and comfort, which attracts people's attention increasingly. Through analyzing the characteristics of snow and ice accumulation on vehicle mudguard, we found that the snow and ice gradually encircled the wheel, the front and rear mudguards, and the posterior side of the fender inner panel with the vehicle traveling, and its thickness decreased from bottom to top. Moreover, the splash and the initial shape of ice and snow were different on the front and rear wheels. Surprisingly, we found that the increase in wheel speed delayed the accumulation of snow and ice in general. Specifically, the rate of accumulation gradually decreased on the middle of mudguards and fender inner panels but increased the on their sides. Besides, because of elastic coatings reducing the freezing adhesive strength of a material, to reduce the negative effects of snow and ice accumulation, we proposed an anti-icing elastic surface on mudguards. The results of laboratory and field test show that the icing was delayed and more gradual after the mudguard had been completely coated with the elastic coating. This suggests that changing the surface elasticity of the mudguard could be used on anti-icing for vehicle chassis.

Influence of cooling rate on the magnetic properties of Hf–Co–Fe–B melt-spun alloy

In the present work, Hf2Co9.5Fe1.5B melt-spun (MS) alloy is synthesized by employing melt spinning at different wheel speeds viz. 16, 20, 24 and 28 m/s to study the effect of quenching on the thermal, structural, microstructural and magnetic properties. The phase purity and the magnetic behaviour of the MS ribbons are highly dependent on the cooling rate that is controlled by altering the tangential wheel speed during melt spinning. Cooling rates are found to increase with increase in wheel speed with a concurrent decrease in the ribbon thickness owing to the increase in the heat transfer coefficient at the thermal contact. The best phase purity and the magnetic properties are found for the ribbons melt-spun at 28 m/s. This could be attributed to the high cooling rate 2.3 × 107 K/s causing crystallization of hard magnetic Hf2Co11B phase leading to refined grain size. A maximum coercivity (HC) ~ 2.18 kOe, remanence ratio (Mr/Ms) ~ 0.61, an appreciable magnetic energy product (BH)max ~ 3 MGOe observed in the MS ribbons at 28 m/s illustrates the critical role of wheel speed in the enhancement of permanent magnetic properties in a single-step without annealing. XRD patterns reveal that the alloy was found to crystallize in orthorhombic Hf2Co11B in addition to cubic Co and Hf6Co23 phases. FE-SEM analysis is carried out to realize the grain morphology and phase identification. The current work exhibits the efficacy of rapid quenching by melt spinning as an effective technique in the development of high-performance Hf2Co9.5Fe1.5B rare-earth-free permanent magnet alloy for future energy applications in the high-temperature regime.

A grinding force prediction model for SiCp/Al composite based on single-abrasive-grain grinding

Grinding is the main processing method for particle-reinforced composites, and grinding force prediction models are very important for research on removal mechanisms. In this study, single-abrasive-grain grinding experiments on SiCp/Al composites were conducted to determine the grinding forces at different grinding process parameters. In addition, a prediction model for the single-abrasive-grain grinding force was established to study the influence of the grinding process parameters and grinding grain angle on the grinding force of SiCp/Al composite. Moreover, multi-abrasive-grain grinding experiments were conducted at different grinding process parameters, which resulted in different grinding forces. The support vector machine (SVM) prediction method based on particle swarm optimisation (PSO) was used to establish a prediction model for the multi-abrasive-grain grinding force; the single-abrasive-grain grinding forces at different grinding grain angles were the input, and the average experimental grain grinding force was the output. The results show that the error between the predicted and experimental grinding forces is below 12%. Furthermore, the grinding force decreases with increasing wheel speed and increases with increasing feed velocity and grinding depth. The PSO–SVM algorithm–based grinding force prediction model can accurately predict the grinding force of SiCp/Al composite and provides theoretical support for improved surface quality.

Influence of wheel speed and ageing on nanostructure and magnetic properties of Cr-doped MnBi magnetic material

In the present work, Mn47Bi50Cr3 ribbons were synthesised employing melt spinning at different wheel speeds ranging from 16 to 28 m/s, to study the effect of quenching rate on the microstructure, morphology and magnetic properties of rapidly solidified alloy. X-ray diffraction studies indicate that the FWHM of diffraction peaks for MnBi increases with the increase in wheel speed, leading to a concurrent decrease in the mean grain size. This could be attributed to the high cooling rate causing homogeneous nucleation leading to refined grain size. The maximum value of coercivity of 11.9 kOe and saturation magnetisation of 54.2 emu/g was obtained for the alloy melt spun at 20 m/s, indicating dependence of coercivity on the grain size, and its orientation, which is largely controlled by the wheel speed. Also, XRD pattern confirms that the MnBi phase fraction is found to be maximum at this wheel speed. Therefore, high-performance nanocrystalline Mn47Bi50Cr3 magnetic material has been synthesised by adjusting the wheel speed and thereby tuning the quench rate. In addition, the phase transformation and variation with respect to temperature and time were studied using thermal analysis technique. Stability of magnetic properties of the alloy with respect to time was also studied after the ageing process.

Effects of wheel speed on surface/subsurface damage characteristics in grinding of glass-ceramics

Glass-ceramic is widely used in optics and other areas because of its good physical and mechanical properties. However, the accompanying hard and difficult to machine characteristic brings great challenges to the commonly used grinding in industry. Previous researches on the removal mechanism of glass-ceramic are basically traditional low-speed scratch and low-speed grinding, ignoring the effect of the wheel speed on surface/subsurface damage. In this study, the effects of the wheel speed on the surface morphology, surface roughness, and subsurface damage of Zerodur glass-ceramics were studied at different wheel speeds based on a multi-step grinding process. Experimental and analytical results showed that increasing wheel speed can restrain the occurrence and development of brittle fractures due to the effects of strain rate and grinding temperature, resulting in fewer and smaller micro-pits and micro-cracks, and thus more signs of plastic flow are observed. In addition, the effects of wheel speed on surface roughness under the semi-finishing grinding stage are not as clearly defined as on that under the rough and finishing grinding stages. The smeared layers on the ground surface, which are related to the compound effects of the grinding temperature and semi-finishing grinding conditions, are recognized as the major contributor to the contradictory surface roughness results. Furthermore, the effect of wheel speed can prevent crack from nucleating and propagating, and then leads to a smaller depth of subsurface damage. Accordingly, there is a general trend toward subsurface damage depth with the increase of undeformed chip thickness, regardless of the grinding conditions. In a word, higher wheel speeds are easier to achieve ductile removal mode and conversely, the glass-ceramic is more prone to a brittle removal mode. The research is expected to provide guidance for grinding-induced damage control and the engineering application in high precision optical parts of glass-ceramic.

Casting of Bar Using a Twin Wheel Caster

A simple twin-wheel caster is proposed for casting thin bars. The lower wheel of this caster has a trapezoidal groove with an area of 25 mm2. A 1070 pure aluminum bar with a convex, not concave and trapezoidal, cross section could be cast at speeds ranging from 3 to 4 m/min. The area of the bar was 38 mm2 when the wheel speed was 3 m/min. The area decreased with increasing wheel speed.

Ductility-oriented high-speed grinding of silicon carbide and process design for quality and damage control with higher efficiency

Grinding of brittle materials is always a removal process of coexisting ductile and brittle removal modes. Ductility-oriented grinding has been regarded as a precision machining pursuit for grinding quality and efficiency. This paper is devoted to investigating ductility-oriented grinding mechanism and process design for quality promotion with a higher efficiency in high-speed grinding of silicon carbide ceramics. The Rayleigh chip thickness model and critical chip thickness model are given to quantitatively calculate the ductile removal proportion. Moreover, the grinding forces and specific removal energy are discussed to reflect the high-speed grinding removal mode. The results show that the increase of wheel speed or decrease of maximum chip thickness could enhance the percentage to a more ductile-oriented removal mode, which will cause a smaller surface roughness with fewer fracture cracks and more plastic removal stripes. Finally, the grinding process conditions for surface roughness below 0.2 μm and ductile removal area higher than 50% are suggested to obtain better surface quality at higher ductile removal and material removal rates.

Hard Magnetic Property Improvement of Melt-Spun PrCo5 Ribbons by Fe and C Doping

Magnetic properties and microstructure of melt-spun PrCo5− x − y Fe x C y ( x = 0 and 0.3; y = 0–0.3) ribbons are studied. For PrCo5 ribbons spun at lower wheel speed of 20 m/s, the coexistence of 2:17 phase with magnetic hard 1:5 phase leads to low coercivity of 0.6 kOe. Increasing wheel speed to 40 m/s imroves the coercivity to 3.3 kOe due to the increased volume fraction of 1:5 phase. Interestingly, magnetic properties of PrCo5 ribbons melt spun at 40 m/s ( Br = 6.4 kG, i H c = 3.3 kOe, and ( BH )max = 4.5 MGOe) are improved to Br = 6.1–6.5 kG, i H c = 7.8–13.5 kOe, ( BH )max = 7.3–8.9 MGOe by doping C, and significantly enhanced to Br = 6.3 kG, i H c = 16.1 kOe, and ( BH )max = 9.3 MGOe for C and Fe co-doped PrCo4.6Fe0.3C0.1 ribbons. The structural and thermo-magnetic analysis confirms that the entrance of Fe and part of C into the crystal structure of 1:5 phase leads to the increase of Curie temperature. Doping proper C content not only uniformly refines grain size and, therefore, improves the squareness of demagnetization curve and ( BH )max, but also increases the volume fraction of 1:5 phase, and thus enhances the coercivity. The increased volume fraction of 1:5 phase and the reduced magnetic domain size due to refined microstructure by co-doping Fe and C make PrCo4.6Fe0.3C0.1 ribbons exhibit a high permanent magnetic performance. They are promising candidate materials for making bonded magnets.

Effect of wheel speed on phase formation and magnetic properties of (Nd0.4La0.6)-Fe-B melt-spun ribbons

The effect of wheel speed on phase formation and magnetic properties of (Nd0.4La0.6)15Fe77.5B7.5 and (Nd0.4La0.6)13.4Fe79.9B6.7 ribbons prepared by melt-spinning method was investigated experimentally. Based on X-ray diffraction results, all melt-spun ribbons consist of the main phase with the tetragonal 2:14:1 type structure and the minor α-Fe phase. Magnetic measurements show the maximum magnetic energy product ((BH)max) and the remanence (Mr) increases firstly and then decreases with the increase of wheel speed, while the coercivity (Hci) increases, resulting from the variation of the average volume fraction of the α-Fe phase and the average grain size in the melt-spun ribbons. Using Henkel plots, the interaction between the 2:14:1 phase and the α-Fe phase in the melt-spun ribbons was analyzed and the intergranular exchange coupling is manifested. Optimal magnetic properties of Hci = 7.27 kOe, Mr = 90.94 emu/g and (BH)max = 12.10 MGOe are achieved in the (Nd0.4La0.6)15Fe77.5B7.5 ribbon with the wheel speed of 26 m/s. It indicates that magnetic properties of Nd-Fe-B melt-spun ribbons with highly abundant rare earth element La can be improved by optimizing alloy composition and preparation process.

Experimental investigations into electric discharge grinding and ultrasonic vibration-assisted electric discharge grinding of Inconel 601

ABSTRACTThe paper presents experimental investigations into electric discharge grinding (EDG) and ultrasonic vibration-assisted electric discharge grinding (UVAEDG) of Inconel 601. The process parameters selected for both processes were duty cycle, discharge current, pulse on time, grinding wheel speed, work speed, and speed ratio to study their influence on responses like surface roughness (Ra) and material removal rate (MRR). It was found that duty cycle, wheel speed, work speed, discharge current, speed ratio, and pulse duration significantly influenced MRR and Ra. It was inferred that MRR increased with increase in duty cycle, wheel speed, current, work speed, and pulse duration in both EDG and UVAEDG processes. It was also inferred that Ra increased with rise in duty factor, pulse on time, and discharge current in EDG and UVAEDG processes.

Tuning the magnetostructural transformation by wheel speed in Mn-Fe-Ni-Ge-Si alloy ribbons

The Mn-Fe-Ni-Ge-Si alloy ribbons are prepared by the melt spinning technique with different wheel speeds and the microstructure, magnetic and magnetocaloric properties are systematically investigated. All the samples reveal the coincident magnetostructural transformation from the ferromagnetic TiNiSi-type martensite to paramagnetic Ni2In-type austenite on heating. The magnetostructural transformation temperature decreases remarkably from 380 K to 320 K with the increase in wheel speed from 10 m/s to 30 m/s. Giant magnetocaloric effect with excellent magnetic reversibility is obtained and the effective refrigeration capacity shows an evident increase, namely 103.9, 125.3, and 185.9 J/kg for three ribbons (under a field change of 0–5 T), though the maximal magnetic entropy change peak value of 27.4 J/kg K is achieved for the sample at 20 m/s. All these features suggest that the wheel speed is an effective way to manipulate the magnetostructural transformation temperature and magnetocaloric properties for MnNiGe-based alloys. The underlying mechanisms are discussed.

Effect of grinding parameters on surface roughness and subsurface damage and their evaluation in fused silica.

Based on micro-indentation mechanics and kinematics of grinding processes, theoretical formulas are deduced to calculate surface roughness (SR) and subsurface damage (SSD) depth. The SRs and SSD depths of a series of fused silica samples, which are prepared under different grinding parameters, are measured. By experimental and theoretical analysis, the relationship between SR and SSD depth is discussed. The effect of grinding parameters on SR and SSD depth is investigated quantitatively. The results show that SR and SSD depth decrease with the increase of wheel speed or the decrease of feed speed as well as cutting depth. The interaction effect between wheel speed and feed speed should be emphasized greatly. Furthermore, a relationship model between SSD depth and grinding parameters is established, which could be employed to evaluate SSD depth efficiently.

High speed and precision grinding of plasma sprayed oxide ceramic coatings

Abstract In this paper, the effects of high speed grinding on six thermally sprayed ceramic coatings were investigated. Grinding was undertaken using four wheel speeds and two work speeds. The responses studied were the following; grinding forces, specific grinding energy, force ratio, surface roughness and surface residual stress. In addition, grinding in traverse mode was also considered in this investigation. An increase in wheel speed resulted in an appreciable reduction in grinding forces. The micro-brittle fracture was the predominant mode of material removal along with micro-cutting in some cases. Further, the surface roughness of traverse ground samples was superior to those obtained using plunge grinding. Finally, it was found that surface residual stresses of samples produced during high-speed grinding are lower than those of samples using precision grinding.

A study on the surface grinding of 2D C/SiC composites

This paper aims at studying the machinability of 2D C/SiC composite with 0°/90° woven carbon fibers using a resin bond diamond grinding wheel. The effects of grinding parameters on the grinding force, force ratio, specific grinding energy, surface topography, surface roughness, and grinding chips were investigated. And the grinding mechanism of the 2D C/SiC composite was discussed by analyzing the chip components and material removal characteristics. The results indicate that the grinding force and surface roughness increase with the increase of feeding speed and depth of cut, while decrease with the increase of wheel speed. The force ratio F n /F t and the specific grinding energy of 2D C/SiC composite were lower than those of conventional ceramics under the defined experimental conditions. Additionally, the grinding chips were composed of carbon powder, carbon fiber fragments, and SiC matrix debris. It can be deduced that the dominant removal mechanism of the 2D C/SiC composite was brittle fracture mode during grinding process.

Phase precipitation behavior of melt-spun ternary Ce2Fe14B alloy during rapid quenching and heat treatment

To understand the structure, phase precipitation and magnetic properties of the ternary Ce-Fe-B alloy, the effects of wheel speed and heat treatment on the melt-spun Ce2Fe14B alloy have been investigated. For the wheel speeds varied from 10 to 50m/s, hard magnetic Ce2Fe14B phase precipitates in as-spun ribbons prepared at 10 and 20m/s. Increasing wheel speed leads to the appearance and increase of amorphous phase and reduced saturation magnetization. For the amorphous ribbons prepared at 50m/s, when the annealing temperature increased from 500°C to 600°C and 700°C, α-Fe phase precipitates first followed by the appearance of Ce2Fe14B phase and grain growth. Transmission electron microscope analysis revealed that large Ce2Fe14B grains and the uniformly distributed small α-Fe grains precipitates from amorphous matrix after heat treatment. The good magnetic properties with saturation magnetization of 11.7kG, remanence of 5.7kG, coercivity of Hc=2.8kOe, and maximum energy product of 2.9MGOe have been obtained in the optimized sample.

Continuous extrusion of a commercially pure titanium powder via the Conform process

It is shown for the first time that cold commercially pure titanium powder can be extruded through a standard Conform machine into fully dense wire with a fine recrystallised microstructure. The grain size has been shown to decrease with increasing wheel speed with an associated increase in tensile strength. The macrostructure of the wire extrudate exhibits a characteristic flow pattern with several regions defined by differences in average grain size and distribution. Finite-element modelling of the process shows the formation of the characteristic macrostructure from powder fed Conform. The process is continuous, utilises standard equipment and does not require powder preheating or inert gas shrouding providing a footing for a true cost reduction in long-section titanium mill product.