Milling Technology Research Articles

Color stability, surface roughness and flexural strength of additively manufactured and milled interim restorative materials after aging.

To evaluate the effect of two different additive manufacturing technologies on the color stability, surface roughness and biaxial flexural strength of interim restorative materials after thermal aging. Disk-shaped specimens were manufactured via two types of vat polymerization methods [Stereo-lithography (SLA) and digital light processing (DLP)] and milling technology (n = 16). CIELab color coordinates and surface roughness were measured before and after thermal cycling. Then biaxial flexural strength tests were performed using a universal testing machine. The data were analyzed by Kruskal-Wallis, one-way ANOVA, and Tamhane and Tukey HSD tests (α < 0.05). There was no significant difference among ΔE values of all study groups (p = 0.191). The milled group showed a higher initial surface roughness value (p < 0.05), while there was no significant difference among the other groups after aging (p = 0.213). DLP had significantly lower flexural strength values than SLA and Milled (p = 0.000). After aging, SLA and DLP were similar to milling method, in terms of color stability and surface roughness. However, milling had an adverse effect on the initial surface roughness. The SLA and milled groups had better mechanical properties than the DLP group.

Understanding HIGMill operation at copper regrind application; operating parameters, wear and mineral liberation

Stirred milling technology has proven its worth globally. The number of installations utilizing this technology has been increasing owing to its energy-efficient operation in fine sizes that leads to improved liberation hence beneficiation performance. HIGMill technology is one of the recent machines having vertical orientation and is in use for wet fine grinding applications. Since the technology is new, understanding its operation regarding to the comminution performance and product specification is of importance for both the academia and industry. This study argues HIGMill operation at copper regrind circuit. Firstly, an initial survey including the concentrate circuit was performed to evaluate the accuracy of the sensors and to provide general knowledge. Then, a series of industrial trials were completed to investigate the influences of operational parameters on energy efficiency, i.e., solid content, the type of grinding media, the alignment of the agitators, agitator material, and bead filling. In the final stage of the study, liberation characteristics of HIGMill products were assessed to provide knowledge on their contribution to the liberation performance of the minerals.

An innovative study on high-performance milling of carbon fiber reinforced plastic by combining ultrasonic vibration assistance and optimized tool structures

At present, the aviation industry puts forward higher requirements for high-performance milling technology of carbon fiber reinforced plastic (CFRP). This paper proposed a sharpening milling CFRP strategy by combining of ultrasonic vibration and optimized tool structure of fluted burr tools. The sharpening cutting mechanisms of the ultrasonic vibration and tool structure were analyzed theoretically first. Next, the milling performance of optimized fluted burr tool was verified compared with conventional helical end mill and the results showed the optimized tool structure had positive effects on damage suppression and surface roughness. On this basis, Ultrasonic vibration-assisted milling (UVM) with the optimized fluted burr tool was applied to further improve the machined surface quality of T800 CFRP. The verification experimental results showed that, compared to conventional milling, both the cutting force and cutting temperature were significantly reduced in UVM, with a maximum decrement of 39.7% and 15.7% respectively. Besides, the surface defects were significantly suppressed and the surface roughness was reduced by 11.4%–37.6% in UVM. The results of this paper suggested that the combination of UVM and optimized fluted burr tool was an efficient and low damages milling strategy for CFRP.

Fit Accuracy of Complete Denture Base Fabricated by CAD/CAM Milling and 3D-Printing Methods.

Digital complete denture fabrication can be accomplished by either milling or three-dimensional (3D)-printing approach in which minimal distortion during processing contributes to effective denture base adaption, which leads to good denture retention. The purpose of this study was to compare the fit accuracy of milled and 3D-printed complete denture bases. The reference edentulous maxillary arch model was scanned to generate virtual denture bases using computer-aided manufacturing software that exports as standard tessellation language files. Denture bases were constructed using a milling and 3D-printing technique using digital light processing method (n = 10). Intaglio surfaces of denture bases were scanned and superimposed on the reference model. The fit accuracy was quantified as root mean square error and evaluated statistically using independent t-test comparisons with a significance level of 0.05. Milled denture bases were significantly more accurate in adaptation than 3D-printed dentures in the overall intaglio area and primary bearing area of denture bases. 3D-printed denture bases demonstrated significantly greater accuracy in adaptation than milled denture bases in the peripheral/posterior palatal seal area. Milled denture bases fit better in the overall and primary stress-bearing areas than 3D-printed dentures, while 3D-printed dentures appeared more accurate in the peripheral seal area, which had a minor undercut that is not suitable for using milling technology.

Surface integrity and fatigue life of Inconel 718 by ultrasonic peening milling

Inconel 718 is widely used in aeroengine hot end parts, such as turbine disks, blades, drive shafts and so on. Its excellent mechanical and thermal properties also lead to the poor machinability, poor surface integrity, thus affecting the fatigue life of the machined part. This paper proposes an ultrasonic peening milling (UPM) technology which can introduce ultrasonic impact to the machined surface during end milling by applying ultrasonic vibration perpendicular to the machined surface. The effects of vibration on the surface integrity and fatigue life of this material were investigated in comparison with conventional milling (CM). The results showed that the best fatigue life of 2.20 × 106 cycles was achieved by UPM. Compared to the CM process, UPM improved the fatigue life by 16.1 times due to better surface quality with fewer surface defects, thicker stress-affecting layers, and the reinforced machined surface achieved in UPM. The results and findings of this study could contribute to the development of new effective and anti-fatigue machining methods for Inconel 718 in the future.

Effect of the degree of milling on the microstructure and composition of japonica rice

The effect of the degree of milling (DM) on the distribution of the residual bran layer on the surface of rice grains and subsequent rice quality is essential for rice milling technology. This study used scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to examine the microstructure of Japonica rice grains, the microstructural changes in different bran portions after milling, and the content and distribution changes of the elements and nutrients in rice after milling to identify the components that can quantify bran residue according to DM. The SEM results revealed that the thickness of the bran layer and the depth of the grooves in different parts of a rice grain varied, while the depth of the grooves differed between varieties. When DM was 12%, aleurone layer (Al) cells embedded in endosperm (En) remained in the dorsal area. It was speculated that this was the reason why there was no significant difference in bran degree when the DM estimated via grain weight loss increased from 10% to 14% ( P > 0.05). The EDS elemental mapping image showed the qualitative distribution of the elements, which was condensed in the bran and uniform in the En. The compositional changes revealed that milling caused the loss of rice nutrients, and the loss rate of DM at 0%–10% was more serious than that of DM at 10%–14%. Higher DM (>10%) could remove marginal bran from the dorsal groove. Therefore, the crude protein, ash, crude fat, dietary fiber, vitamin B1 (VB1), and vitamin B2 (VB2) content did not change significantly ( P > 0.05), while the magnesium (Mg), kalium (K), and phosphorus (P) levels decreased substantially ( P < 0.05). The microstructural and compositional changes indicated that the DM estimated via the grain weight loss increased from 2% to 10%, with the bran decreasing progressively. The DM estimated via the grain weight loss increased from 10% to 14%, with minimal changes in the residual bran in the dorsal grooves of the rice grains, while the Mg, P, and K levels presented precise DM indices during the rice milling process. This result will provide a theoretical reference for the accurate evaluations of DM.

Enabling Li3.75Si alloy coupled with Argyrodite Electrolyte with Desirable Performance for All-solid-state Batteries

With excellent safety and outstanding energy density, all-solid-state batteries is of a prospect for surpassing liquid Li+ batteries. Li6PS5Cl, exhibits desirable ductility and good Li+ conduction property, which is the most commonly used solid-state electrolyte. Herein, Li3.75Si alloys have been prepared by high energy milling technology as an anode to couple with NCM811 cathode and demonstrated an outstanding capacity. During the charging/discharging process, a microstructural defect surface was obtained, and a large impedance interface was verified by EIS tests.

Fe-Al bimetallic oxides functionalized-biochar via ball milling for enhanced adsorption of tetracycline in water

The clusters formed by modified materials on its surface makes the application of functionalized biochars in adsorption face a great challenge. Here, a facile ball milling technology was innovatively proposed to tailor Fe-Al oxides-laden bagasse biochar to fabricate a novel adsorbent (BMFA-BC). Benefited from the increased exposure of Fe-Al oxides and, more importantly, enhanced functional groups by ball milling, the adsorption capacity of BMFA-BC for aqueous tetracycline reached up to 116.6 mg g−1 at 298 K. And the adsorption performance was temperature-dependent. Characterization analysis, batch sorption (thermodynamics, kinetics, isotherms, chemical factors) as well as data modeling illustrated that this superior adsorption ability could be attributed to π-π conjugation, H-bonding, complexation as well as pore filling. BMFA-BC displayed good adsorption capacity in multiple aqueous environments. The excellent regeneration ability, magnetic susceptibility ensured its viability for sustainable pollutants removal. These superiorities revealed that BMFA-BC was a suitable sorbent for antibiotics elimination.

Lightweight and flexible sensors based on environmental‐friendly poly(butylene adipate‐co‐terephthalate) composite foams with porous segregated conductive networks

AbstractConstructing the microcellular structure in the conductive polymer composites (CPCs) is a promising approach to improve the sensitivity and durability of the piezoresistive sensor. Selectively placing the conductive fillers, to form the segregated network between the polymer region, can effectively improve the electric performance of CPCs. However, few researches have focused on the influence of the polymer bead size on the segregated network and the large‐scale production of spherical polymer beads with low cost is still difficult to realize. Herein, plenty of regular‐shaped poly(butylene adipate‐co‐terephthalate) (PBAT) beads were manufactured through underwater pelletizing process, which was further coated with carbon nanotube (CNT) particles with the assistance of ball milling technology, and eventually the sensor was successfully fabricated through supercritical carbon dioxide (scCO2) bead foaming technology. The lightweight and flexible sensor exhibited the uniform cell structure with the mean cell size of 51.0 μm and cell density of 3.9 × 108 cells/cm3 when the pelletizing cutter speed was 2500 rpm and the foaming temperature was 117.5°C. And the conductivity of the sensor reached 6.5 S/m incorporated with 3 wt% CNT, which possessed high sensitivity, good stability and long‐term durability, attributed to its excellent microcellular structure and segregated conductive network.

Water-Soluble Poly(vinyl alcohol)/Biomass Waste Composites: A New Route toward Ecofriendly Materials.

With the intention to abate the pollution arising from the improper handling of petroleum-based plastic, green composites consisting of biodegradable plastics and biomass wastes have received widespread attention. However, the balance between mechanical performance and biodegradability still has not been reconciled and evaluated. Herein, a concept for water-soluble poly(vinyl alcohol) (PVA)/biomass waste composite materials is proposed. Instead of degrading to small molecules, the PVA matrix can dissolve in water within the soil. Moreover, after PVA was composited with waste cottonseed shell (CTS) using solid-state shearing milling (S3M) technology, considerable mechanical and thermal performance was achieved, with the maximum tensile strength and degradation temperature of the PVA/CTS composites reaching 10.3 MPa and ∼250 °C, respectively. Moreover, the soil burial test demonstrated that even if PVA cannot degraded in environment within a short term, its water-soluble nature ensures its environmental friendliness, as the PVA matrix can dissolve in soil in 10 days without imposing any adverse effects on either plants (wheat) or animals (earthworm). This work not only describes the preparation a series of ecofriendly PVA/biomass composites but also provides new insight into the environmental friendliness of PVA-based materials.

A D-Band Manifold Triplexer With High Isolation Utilizing Novel Waveguide Dual-Mode Filters

This letter presents our design of a wideband manifold-coupled triplexer with high isolation in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> -band. The basic structure of channel filters is the novel TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">120</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> dual-mode cavity, which provide two reflection zeros and one transmission zero. To achieve good computational efficiency and design accuracy, the space-mapping technique, consists of a coarse distribute model and a fine full-wave electromagnetic model, is adopted in the development of the triplexer. The proposed triplexer is fabricated by high-precision computer numerical control milling technology. The measured results are all in good agreement with the simulated ones. The measured lowest in-band insertion loss is 0.54/0.62/0.55 dB for three channels, respectively. The return loss of each channel is better than 14 dB and the isolation between each channel is better than 45 dB.

EDM milling based on a 6-DOF serial robot

Aiming at the problems of insufficient flexibility and limited size of the workpiece in traditional EDM milling, an EDM milling based on a 6-DOF serial robot is proposed in this study. To realize the rapid adjustment of the machining gap, a tool electrode servo motion device was invented and installed at the end of a 6-DOF serial robot, and a servo control strategy of the tool electrode vertical trajectory fallback was proposed. Then, to achieve the controllable thickness of every layer in EDM milling based on a 6-DOF serial robot, the servo control strategy of limited motion of the tool electrode on the basis of vertical servo control and a fix-length compensation method to compensate the tool electrode wear was proposed. Finally, to verify the correctness and effectiveness of the servo control strategy and wear compensation of the tool electrode, the trapezoidal groove structures on the plane workpiece and cylindrical workpiece were machined by EDM milling based on a 6-DOF serial robot, respectively. Also, to verify the machining ability of complex trajectories on the space surface of the workpiece of EDM milling based on a 6-DOF serial robot, three complex trajectories, such as EDM, Chinese character “China,” and “Chinese knot,” was designed and machined on the hemispherical workpiece with the radius of 38 mm. The feasibility and effectiveness of EDM milling technology based on a 6-DOF serial robot were verified, which has great market application potential.

Fluorine-terminated functionalized liquid metal/silicon carbide binary nanoparticles for polyvinyl alcohol composite films with high in-plane thermal conductivity and ultra-low dielectric constant

Highly thermally conductive and low dielectric constant are among the most sought-after properties of flexible polymer-based thermal-management materials (TMMs). However, it remains a formidable challenge to develop efficient thermal dissipation materials with fascinating comprehensive performance. In this work, we present an interfacial engineering strategy using trifluoropropyltriethoxysilane (TFPTES) to act as a thermal linker at granular silicon carbide-liquid metal (SiC-LM) binary interfaces (SiC-LM@F) in the polyvinyl alcohol (PVA) matrix, in which the LMs merely partially anchored to the surface of binary filler by a controllable ball milling technology. The strong hydrogen bonding and/or compact “shoulder-to-shoulder” contact between the binary components and matrix interfaces confer an expressway for the propagation of interfacial phonons. For this, the developed PVA/SiC-LM@F composite film demonstrates a high in-plane TC of 10.2 W m−1 K−1 and ultra-low dielectric constant of 1.49 at 106 Hz at 40 wt% SiC-LM@F loading content, which is more superior to those of the other counterparts in this experiment. Additionally, the obtained PVA/SiC-LM@F composite film also reveals favorable tensile strength, excellent electric insulation, and efficient cooling capacity. This interfacial engineering strategy is expected to offer a versatile solution to the design and construction of advanced thermal-management materials (TMMs).

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co-salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides.

In this paper, we report the mechanochemical synthesis of unsymmetrical salens using grinding and ball milling technologies, respectively, both of which were afforded in good yield. The chelating effect of the unsymmetrical salens with zinc, copper, and cobalt was studied and the chiral Co–salen complex 2f was obtained in 98% yield. Hydrolytic kinetic resolution (HKR) of epichlorohydrin with water catalyzed by complex 2f (0.5 mol %) was explored and resulted in 98% ee, suggesting complex 2f could serve as an enantioselective catalyst for the asymmetric ring opening of terminal epoxides by phenols. A library of α-aryloxy alcohols 3 was thereafter synthesized in good yield and high ee using 2f via the phenolic KR of epichlorohydrin.

Effects of ball milling on Structure and Electrochemical Properties of Na4MnV(PO4)3

Na4MnV(PO4)3 is regarded as a promising candidate as cathode material for Na-ion batteries (SIB) due to its low cost and high energy density. However, it suffers from fast capacity decay upon cycles, hindering its further commercialization. The ball milling technology was adopted in this study to control the particle size of Na4MnV(PO4)3, and the correlation of electrochemical properties was investigated. With increasing ball milling time, particle size was greatly reduced. The material with 20 minutes of ball milling displayed the best cycling stability and rate capability. It delivered a reversible capacity of 77.1 mAh/g at 0.5 C after 80 cycles, much higher than that of pristine Na4MnV(PO4)3. The decreased particle size might be to blame for the enhanced electrochemical performance, which effectively increased the interfacial contact with the electrolyte and greatly reduced the length of Na-ion diffusion in active particles.

Effects of Jet Milling Pretreatment and Esterification with Octenyl Succinic Anhydride on Physicochemical Properties of Corn Starch.

(1) Background: In this study, aiming at the problems of low efficiency and high energy consumption in the esterification reaction of OSA and starch, the jet milling technology was used to pretreat corn starch and starch raw materials with different pulverization strengths were obtained by controlling the speed of the classifier. (2) Methods: The starch obtained under different classification speeds was modified by esterification with OSA. Using CLSM, FTIR, XRD, NMR, FTIR, XPS, and other technologies, the modification effect was verified, and the physical and chemical properties of J-OSA-Starch such as DSC, RVA, transparency, and emulsifying properties were determined. (3) Results: Jet milling pretreatment significantly reduced the particle size of corn starch and improved the reaction efficiency and degree of substitution during esterification with OSA. After pretreatment, the corn starch granules were broken, and the relative crystallinity was significantly reduced. CLSM, FTIR, XPS, and NMR confirmed the esterification of corn starch with OSA, which increased with increasing crushing strength. The thermodynamic properties and viscosity of J-OSA-starch decreased with the increase in the classification speed. Jet milling pretreatment enhanced the clarity, emulsifying activity, and emulsifying stability of OSA-modified corn starch. (4) Conclusions: Jet milling pretreatment can effectively increase the esterification efficiency of starch and OSA. Therefore, jet milling can be used as a pretreatment to improve the esterification of starch OSA and produce modified starch for industrial applications.

Robotic mobile and mirror milling of large-scale complex structures.

Robotization, miniaturization and portability have become the new development trend of milling equipment for large-scale complex structures, and the robotic mobile and mirror milling technology has reached remarkable progress in practical production.

Marginal and Internal Fit and Intaglio Surface Trueness of Temporary Crowns Fabricated with Stereolithography, Digital Light Processing, and Milling Technology.

To evaluate the fit and trueness of temporary crowns fabricated with 3D printing vs milling technologies and to analyze any existing correlations between fit and trueness. Marginal and internal fit and trueness were evaluated. Groups were compared using Kruskal-Wallis H test (α = .05), and correlations were analyzed using Spearman rank correlation analysis (α = .0016). Intaglio surface trueness was partially correlated with the marginal and internal fit (P < .0016). High intaglio surface trueness in the axial and occlusal regions may result in poor marginal fit. In the axial region, high intaglio surface trueness may adversely affect both the marginal and internal fit.

Corrigendum to “Recent advances in the treatment of contaminated soils by ball milling technology: Classification, mechanisms, and applications” [J. Clean. Prod. 340 (15 March 2022) 130821

Corrigendum to “Recent advances in the treatment of contaminated soils by ball milling technology: Classification, mechanisms, and applications” [J. Clean. Prod. 340 (15 March 2022) 130821

The Impact of Sintering Technology and Milling Technology on Fitting Titanium Crowns to Abutment Teeth-In Vitro Studies.

Introduction: The aim of the study is to evaluate the marginal and internal fit of titanium alloy (Ti6Al4V) crowns using the Selective Laser Melting (SLM) method and CAD/CAM milling. Materials and Methods: The research materials are abutment teeth and prosthetic crowns. The method is based on scanning the abutments and the interior of the substructures, creating their 3D models, using the program for comparison, and determining error maps of fitting crowns to the reference models, in the form of positive and negative deviations. Adding the deviations gives information about the tightness of the crowns. The Shapiro–Wilk test and the one-way ANOVA analysis were performed. The level of significance was p = 0.05. Results: The crowns made in SLM, a slightly better internal fit was found than for milled crowns, as well as a comparable marginal fit. The mean deviations for the sintering were the values [mm]: −0.039 and +0.107 for tooth 15 and −0.033 and +0.091 for tooth 36, and for the milling –0.048 and +0.110 for tooth 15 and –0.038 and +0.096 and for tooth 36. Conclusion: Based on the research conducted and the experience in therapeutic procedures, it can be indicated that the fitting of titanium alloy crowns in SLM and milling meets the clinical requirements. To evaluate the technology, a method was developed that determines the accuracy of mapping the shape of the tooth abutments in the crown substructures for the individual conditions of the patient.