Polishing Angle Research Articles

Preparation of Cemented Carbide Insert Cutting Edge by Flexible Fiber-Assisted Shear Thickening Polishing Method.

Reasonable cutting edge preparation can eliminate microscopic defects and improve the performance of a cutting tool. The flexible fiber-assisted shear thickening polishing method was used for the preparation of cemented carbide insert cutting edge. The influences of the polishing angle and polishing speed on the cutting edge preparation process were investigated, and the cutting edge radius and K-factor were employed as evaluation indexes to evaluate the edge shape. A prediction model of the cutting edge radius was also established using the mathematical regression method. The results show that the polishing angle has a more significant effect on the cutting edge radius. The cutting edge preparation efficiency is the highest under the polishing angle of 10°, and the cutting edge radius increased from the 15 ± 2 μm to 110 ± 5 μm in 5 min. The cutting edge shape can be controlled by adjusting the polishing angle, and the K-factor varies from 0.14 ± 0.03 to 0.56 ± 0.05 under the polishing angle (from −20° to 20°). The polishing speed has a less effect on the cutting edge radius and shape, but increasing the polishing speed within a certain range can improve the efficiency of cutting edge preparation. The flank face roughness decreased from the initial Ra 163.1 ± 10 nm to Ra 5.2 ± 2 nm at the polishing angle of −20°, which is the best polishing angle for the flank face surface roughness. The ANOVA method was employed to evaluate the effective weight of the polishing angle and polishing speed on preparation efficiency. The polishing angle (86.79%) has the more significant influence than polishing speed (13.21%) on the cutting edge preparation efficiency. The mathematical regression method was used to establish the model of the prediction of the cutting edge radius with polishing angle and speed, and the models were proved rationally. The results indicate that the FF-STP is an effective method for the high consistency preparation of cemented carbide insert cutting edge.

Spring-dashpot vibrational model for the investigation of viscoelasticity in gelatinous abrasive media and subsequent control of parameters for the blast polishing of Ti-6Al-4 V alloy

Blast polishing offers an operator-friendly solution to many of the previously encountered polishing difficulties. However, the process lacks studies into the control of key parameters, one of which is viscoelasticity (particularly present in biological-based abrasive medias). Together with analytical-empirical models, a vibrational spring-dashpot model is presented, which characterizes the impact force, contact time, and damping ratio/coefficient of polishing media upon impact; as well as the effects of damping on contact parameters: stress, deformation, and area of contact. These are compared to experimentally gathered results for verification of the model. Impact force is shown to decrease dramatically with increasing hydration while increasing linearly with an increase in kinetic energy. Experimental findings reveal that 50% wet contact exhibits a 340% reduction in force magnitude compared to dry contact. Contact time results show an exponential increase with an increase in hydration. Research findings also show that higher hydration levels result in lower damping ratios and that higher kinetic energies (related to higher hydration levels) tend toward a decrease in damping ratio. Similarly, media damping coefficients decrease with both hydrational increases and kinetic energy increases. Results show that contact stress is reduced at higher hydration levels, which is mainly due to higher contact areas, and hence it was noticed that an increase in hydration prevents occurrence of chipping and brittle failure on the workpiece surface. Contact stress is shown to reduce by 325% from a 10% wet contact to a 50% wet contact. A high hydration of 30 to 50%, a high impinging velocity of value 31.4 m/s and above, a low stand-off distance of value 20 mm and below, a 45° polishing angle, and a polishing time of 20 to 40 min provide the most optimal parameters for efficient polishing to achieve a mirror finish on an additive manufactured Ti-6Al-4V component. The findings stipulated provide a base on which to further characterize the process and aim to promote further development and optimization of the blast polishing process.

Effect of substrate surface finish and particle velocity on fatigue performance of cold spray coated A6061 aluminum alloy

Cold spray coatings made with powder of the same material as the substrate can be used to improve fatigue performance and/or to repair damaged parts. The effects of substrate surface finish and particle impact velocity on the bond strength and fatigue performance of Al-6061-T6 substrates coated with Al-6061 powder by using high pressure cold spray (CS) were investigated. To evaluate the effect of particle velocity, coatings were prepared by using both nitrogen (N2) and helium (He) as carrier gases. A new method for substrate surface preparation was introduced by low angle spraying (LAS) with the same powder prior to coating. The bond bar specimens in polished, semi-polished, grit-blasted (GB) and low angle sprayed (LAS) conditions were coated and tested for bonding strength. The microstructural characteristics and microhardness profiles of the coated samples were also evaluated. Fatigue tests on uncoated and coated samples were conducted under fully-reversed axial loading in load-controlled condition. The failure mechanism was identified by evaluating the fracture surfaces using scanning electron microscopy. The results showed that both bonding strength and fatigue performance of the coated specimens prepared by using He-gas were significantly higher than those prepared by using N2. Among the N2-sprayed coatings, the bonding strength of on LAS substrates were significantly higher than that of the other surface conditions, and the bonding strength of coatings on GB substrates was superior to that of polished and semi-polished samples. However, the fatigue performance of LAS-coated samples was inferior compared to uncoated samples due to cracks initiating in the coating and propagating into the substrate. The fatigue behavior of GB-coated specimens was similar to the uncoated samples due to delamination of the coating which resulted in stopping the cracks that initiated in the coating.

Structure optimization of gold-sputtered side-polished U-shaped plastic optical fiber SPR sensor

PurposeThis study aims to optimize the structure of gold-sputtered U-shaped plastic fiber sensors.Design/methodology/approachA group of U-shaped Au-sputtered plastic optical fiber sensing probes with polishing angles of 45°, 90° and 135° is prepared.FindingsThe experimental results show that the spectral response and sensitivity of the sensor at 45°polishing angle is twice that of the sensor at 90°.Research limitations/implicationsDue to the limitations of laboratory temperature and equipment, the overall effect has not reached the ideal, but the expected effect has been obvious. Experiments also optimize the sensor.Practical implicationsOptical fiber sensing has always been an indispensable part of various fields.Social implicationsSensor optimization is of great help to the progress of technology and the development of science and technology.Originality/valueThe authors have no conflicts of interest to disclose.

Shear thickening polishing of the concave surface of high-temperature nickel-based alloy turbine blade

High-temperature nickel-based alloy, which is a valuable crucial material for fabricating functional components, is commonly used to fabricate turbine blades. However, the concave surface of the turbine blade is much difficult to be polished. In this work, shear-thickening polishing (STP), which employed the shear-thickening mechanism of non-Newtonian power-law fluid, was utilized to achieve high efficiency and high-quality polishing of the concave surface of the high-temperature nickel-based alloy turbine blade. The finite element simulation of the pressure and velocity distribution on the concave surface during STP process was carried out by ANSYS, and the effects of different polishing angles, polishing velocities, pH values of polishing slurry and Fenton's reagent on the surface morphology and roughness of the workpiece were investigated by experiment. The comparison between simulation and experimental results indicated that the suitable polishing angle is 45°. The best surface can be obtained with a pH value of 6.5. With the increase of the polishing speed, polishing efficiency improved gradually. The workpiece surface was improved by adding 0.5% hydrogen peroxide (H2O2) and 0.15% FeSO4 in the polishing slurry. In the final, surface roughness of the turbine blade was reduced rapidly from Ra = 72.3 nm to Ra = 4.2 nm after 9 min polishing under the appropriate conditions. The research results provide reference and basis for high-temperature nickel-based alloy turbine blade polishing.

Investigation on the Polarization Dependence of An Angled Polished Multimode Fibre Structure

An angled polished multimode (APM) fibre structure is described for the first time, to the best our knowledge, and its polarization dependence is investigated theoretically and experimentally. Two angled planes are established in the multimode fibre (MMF) section of a single-mode-multimode-single-mode (SMS) fibre structure using the fibre side-polishing technique, forming the APM fibre structure. This designed circular asymmetric geometry induces different propagation characteristics for the TE and TM modes within the MMF. Simulated and experimental results both show that this difference is enhanced as the polishing angle increases, and a maximum extinction ratio (ER) of the spectrum of 13 dB is achieved at a polishing angle of 85°. This polarization-dependent device has a simple fabrication process and is free from the limitation of coating functional materials, which is expected to be applied in non-linear optics, fibre laser, and optical fibre sensing fields.

Refractive index sensing characteristics of dual-core PCF based on surface plasmon resonance

A novel refractive index sensor based on surface plasmon resonance (SPR) is proposed in this paper, which is induced by coating a metal film on the surface of a section of D-shape-polished dual-core photonic crystal fiber (DC-PCF). The mechanism of SPR resonance and sensing principle are discussed theoretically. The sensing characteristics as a function of the polished angle, depth, the material of metal film, coating layer thickness are analyzed comprehensively. A DC-PCF with a 60° polished angle, 58.02 μm polished depth is fabricated with a silver coating layer of 70 nm thickness experimentally, which demonstrates that the refractive index sensitivity can be as high as 3580 nm/RIU in the refractive index range of 1.33–1.43.

The Influence of Structural Parameters on the Surface Plasmon Resonance Sensor Based on a Side-Polished Macrobending Plastic Optical Fiber

In this paper the influences of the structured parameters, namely, metal layer thickness, polished depth, macrobending radius and polished angle on the refractive index sensing performances for the side-polished macrobending plastic optical fibers (POFs) based surface plasmon resonance (SPR) sensors were investigated. A simple and controllable rotary grinding technique was introduced to fabricate the proposed sensor. The performances of sensitivity, resolution and full width at half maximum (FWHM) were evaluated. The results have demonstrated that the SPR sensor performances could be improved by changing the structural parameters, and the highest sensitivity obtained was 4793.1 nm/RIU when the external refractive index was 1.410. The proposed POFs based SPR sensors are easy fabrication, robust, and compact in size, which are useful for chemical and biological sensing.

Dual-channel surface plasmon resonance refractive index sensor based on modified hetero-core structure fiber

We propose and demonstrate a novel dual-channel SPR refractive index sensor based on hetero-core structure fiber. For the traditional hetero-core structure fiber SPR sensor, the resonance wavelength range is unchangeable. We solve this issue by polishing the traditional hetero-core structure fiber as circular truncated cone shape. By this method, we can adjust the resonance wavelength range flexible by changing fiber polishing angle. With increasing of fiber polishing angle, the resonance wavelength range will red-shift. When fiber polishing angle is 14°, and refractive index range is from 1.333 to 1.385, the resonance wavelength range is from 754 nm to 965 nm, which is away from that of the traditional hetero-core structure fiber SPR sensor (600 nm to 700 nm). Therefore, we realize dual-channel sensing by wavelength division multiplexing technology. The sensitivity of two channels are 1980.77 nm/RIU and 4057.69 nm/RIU respectively. In addition, the resonance wavelength and sensitivity of the sensor have a well consistency no matter which working way we adopt. The proposed dual-channel SPR sensor has important applications for multiple analytes detection.

High-precision micro-displacement optical-fiber sensor based on surface plasmon resonance.

We propose and demonstrate a novel optical-fiber micro-displacement sensor based on surface plasmon resonance (SPR) by fabricating a Kretschmann configuration on graded-index multimode fiber (GIMMF). We employ a single-mode fiber to change the radial position of the incident beam as the displacement. In the GIMMF, the angle between the light beam and fiber axis, which is closely related to the resonance angle, is changed by the displacement; thus, the resonance wavelength of the fiber SPR shifts. This micro-displacement fiber sensor has a wide detection range of 0-25μm, a high sensitivity with maximum up to 10.32nm/μm, and a nanometer resolution with minimum to 2nm, which transcends almost all of other optical-fiber micro-displacement sensors. In addition, we also research that increasing the fiber polishing angle or medium refractive index can improve the sensitivity. This micro-displacement sensor will have a great significance in many industrial applications and provide a neoteric, rapid, and accurate optical measurement method in micro-displacement.

Optimization of polishing parameters for optical coupler based on side-polished photonic crystal fiber

The rapid development in areas such as fiber-optic communication, fiber lasers, and high power transmission has generated an increasing demand for photonic crystal fiber (PCF). However, there is no well-proven approach for PCF coupler fabrication because most approaches proposed introduce defects that are non-negligible in practice. Previously, we have made an attempt by applying side-adhering technique to PCF coupler fabrication. This paper presents our recent effort in establishing a model of side-polished PCF (SPPCF) coupler and tuning various fabrication parameters in search for its desirable characteristics. It is found that the optimal coupling effect is achieved when the residual radius is set 5.7 μm and the polishing angle is set 0°. The optimizations presented in this paper may serve as a foundation for further research and development of SPPCF coupler.

Investigation of subsurface damages and surface roughness in grinding process of Zerodur® glass–ceramic

Abstract Subsurface damages and surface roughness are the two significant parameters which determine the efficiency of optical components. In this study, a cup diamond wheel is used in grinding process of the specimens made of Zerodur® glass–ceramic, to investigate the influences of grinding parameters on the SSD and SR. The grinding parameters used in this study are depth of cut, cutting speed and feed rate; and effects of these parameters are studied. The experimental results are compared with the modified model of Lambropoulos, proposed by Li, and a good accordance is observed between them. Two measuring techniques were used to study the SSD. Cross-sectional polishing method and angle polishing method; the first one, suitable for studying the material removal mechanism and the other one convenient for examining the depth of subsurface damages and distribution of micro-cracks in the ground surface, respectively. A novel technique is introduced to measure the cracks length in which the sum of all cracks in a specific area of a SEM micrograph is calculated by image processing method and regarded as a factor to study the cracks length. Also, a statistical model is developed in order to predict the surface roughness and a good agreement is observed between the experimental results and the predicted values.

Optimization of an angled fiber probe for common-path optical coherence tomography

We studied the optimization of common-path optical coherence tomography (CP OCT) sensitivity through an angled fiber probe. The magnitude of reference power derived from the tip of the fiber was optimized through careful selection of the polishing angle. We experimentally measured the signal-to-noise ratio (SNR) at different polishing angles to validate the effectiveness of this technique. We also obtained OCT images with the reference optimized CP OCT with more than 8 dB improvement in SNR.

Fused angle-polished multi-points side-pumping coupler for monolithic fiber lasers and amplifiers

We have developed theoretical model to investigate characters of fused angle-polished side-pumping coupler for monolithic fiber lasers and amplifiers. In the simulation the interplay of different couplers is considered. Five pumping fibers with different polished angles are employed in the experiment. The results showed that, the backward coupling efficiency, forward and backward pumping leakage are lower than 4%, 8% and 10% respectively, while the forward coupling efficiency is about 100%, with the polished angle suitable for commercial fibers. The experimental results agree well with the simulations. Furthermore, we fabricate a two-points co-propagating fused angle-polished side-pumping coupler, with the coupling efficiency of 94.1% and 87.9%. These couplers are quite suitable for multi-points side-pumping high power monolithic fiber lasers and amplifiers.

Note: Fabrication of tapered fibre tip using mechanical polishing method

Tapered fibre tips fabricated using mechanical polishing method is studied. The fibre tips are formed by sequential polishing flat-ended single mode fibres with decreasing aluminium oxide polishing film grit size. Based on the proposed technique, tapered fibre tips with cone angle ranging from 30° to 130° are fabricated by controlling the polishing angle. Besides the variety of cone angle, considerable smoothness of the fibre tip surface may assist in good metal coating and hence a well-defined aperture can be obtained. In addition, this paper presents a two-step hybrid fabrication method combining the proposed polishing method with chemical etching method to increase the possible fibre tip cone angles achievable by chemical etching method.

TEM Analysis of Multilayered Co/Cu Nanowire Synthesized by DC Electrodeposition

As-received multilayered Co/Cu nanowire arrays were examined by TEM, which were synthesized by pulsed DC electrodeposition using anodized aluminum oxide (AAO) templates. The multilayered Co/Cu nanowire exhibited magnetism in the perpendicular direction to the long wire axis. These nanowire can be applied to sensor array, magnetic bead(biocompatible), MRI contrast enhancing agent, ferro-fluid. Although the characterization of the multilayered Co/Cu nanowire using XRD and VSM and microstructural analysis using TEM on the bare nanowires extracted from AAO templates have been reported, interface analysis between Co and Cu phase or HREM analysis has not been reported in detail. We have prepared TEM specimen with large thin area which was appropriate for the interface analysis between Co and Cu layer without removing AAO templates using tripod polishing method. Tripod polishing proved very efficient to secure the large observable area during TEM session since the polishing angle can be precisely controlled, regardless of the mechanical strength differences in constituents. Thus we could observe not only the interface between Co and Cu layer but also the interface between the metallic layers and AAO templates. Microstructure, composition, and the concentration variation of each Co and Cu layer and the interfaces were analyzed with TEM and STEM.

Coupling efficiency of angle-polished method for side-pumping technology

The angle-polished method for side-pumping technology that is useful in high-power fiber lasers and fiber amplifiers is investigated. By geometric optics, the simple model for calculation of the coupling efficiency is derived. Numerical simulations show that both the polished angle of multimode fiber and the refractive index of index-matching material are pivotal to the side-coupling efficiency. By experiments, coupling efficiency of 80.2% and maximum coupling power of 1.12 W are measured for a 200-µm multimode fiber and a double-clad fiber with a 400/340-µm D-shaped inner cladding. Slope efficiency of 56% and output power of 282 mW are demonstrated in a D-shaped Yb-doped double-clad fiber laser by the side-pumping system with the angle-polished method.

TEM assessment of HVOLF thermally sprayed Al–12 wt.% Sn–1 wt.% Cu alloy

Abstract The high velocity oxy-liquid fuel (HVOLF) thermal spray technique has the potential to fabricate thick layers based on the Al–12 wt.% Sn–1 wt.% Cu alloy. The microstructure of the as-sprayed coatings exhibits several levels of complexity due to the effects of rapid quenching and metastable phase formation. The use of tripod polishing and low angle milling procedures have allowed the sectioning of large thin areas of material for plan view and cross-sectional transmission electron microscope (TEM) observation, thereby clearly delineating regions of material that have undergone differing patterns of melting and freezing during the HVOLF process. Comparison has also been made with the pre-sprayed gas-atomised powder. The microstructure of most of the larger gas-atomised powder particles comprises Al dendrites surrounded by Sn interdendrite phase. Conversely,

Microstructural examination of solar-beam-irradiated TiN hard coatings

Microstructural examination and characterization of hard coatings may enable engineers to improve coating deposition processes and bring tribologists a step closer to the understanding of tribological mechanisms responsible for the failure of hard coatings. Since a thin oxide film on top of hard coatings could act as a solid lubricant and improve the wear and fretting behaviour of these coatings, the examination of such films is of special interest. The oxide films were produced on physical-vapour-deposited TiN coatings a few micrometres thick by irradiation with concentrated solar energy in ambient atmosphere at 800°C and for holding times between 10 and 350 s. For the analysis and characterization of the oxidized coating microstructure, micro-Raman spectroscopy and atomic force microscopy have been performed on oxidized surfaces. Light optical and scanning electron microscopy were done on polished low angle and fractured coating cross-sections, while transmission electron microscopy has been performed on thin foils showing the coatings either parallel or cross-sectional to the surface. The dark grey oxide films found on TiN have been identified as rutile TiO 2. These layers appeared with a uniform thickness but contain a non-uniform porosity over the oxide film thickness. Close to the TiN interface generally a higher porosity has been observed in the rutile. No sharp interface between TiN and rutile could be found. The TiN-rutile interface is characterized by oxide formation along the TiN grain boundaries.