Conventional Polishing Techniques Research Articles

Noninvasive characterization methods for ultra-short laser pulse induced volume modifications

We present two noninvasive characterization methods to investigate laser induced modifications in bulk fused silica glasses. The methods discussed are immersion microscopy and scanning acoustic microscopy (SAM). SAM shows merits in measuring the distance from sample surface to the first detectable density change of the modification, while immersion microscopy offers a look into the modification. Both noninvasive methods are preferred over conventional polishing or etching techniques due to the facts, that multiple investigations can be done with only one sample and lower time expenditure. The type II modifications were introduced by focusing laser pulses with high repetition rates into the fused silica.

Evaluation of the Effects of Different Polishing Protocols on the Surface Characterizations of 3D-Printed Acrylic Denture Base Resins: An In Vitro Study.

Chairside polishing kits are an alternative to laboratory polishing techniques. The effects of using a chairside polishing kit on a three-dimensional (3D)-printed acrylic denture base (ADB) have not been reported previously. Thus, this study aimed to evaluate the effects of different chairside polishing techniques on the surface characterizations of ABD, including surface roughness average (Ra), average maximum profile height (Rz), and scanning electron microscopy (SEM) representations. One hundred and twenty disc-shaped specimens were fabricated from one conventional heat-polymerized (HP) ADB resin and two 3D-printed (Asiga (AS) and NextDent (ND)) ADB resins (n = 40 per material). Each group was further divided based on the polishing protocol (n = 10) as follows: conventional polishing protocol (C), microdont chairside polishing kit (M), shofu chairside polishing kit (S), and an unpolished group (U). The Ra and Rz values were measured using an optical profilometer. Two-way ANOVA and post hoc tests were used for data analysis (α = 0.05) at significant levels. In unpolished groups, there was a statistically significant difference between HP-U vs. AS-U and ND-U groups (p < 0.0001). For Ra, the lowest values were observed in HP-C, AS-S, and ND-C. While the highest values were shown in all unpolished groups. Within the material, there were statistically significant differences between the three polishing protocols (C, M, and S) vs. unpolished (p < 0.0001), while there was no significant between C, M, and S groups (p = 0.05). The Rz values had the same pattern as the Ra values. The two chairside polishing kits were comparable to conventional polishing techniques, and they can be recommended for clinical application.

Review on robot-assisted polishing: Status and future trends

Nowadays, precision components have been extensively used in various industries such as biomedicine, photonics, and optics. To achieve nanometric surface roughness, high-precision polishing is mandatory. Compared with the conventional polishing techniques, the robot-assisted polishing has the advantages of flexible working ranges and low cost. Therefore, it has been more widely deployed in demanding polishing tasks. However, few review articles were found on this topic to provide a general progress on the development of the robot-assisted polishing technology. This paper reviews the recent advancement of the robot-assisted polishing. Firstly, the integration of robots with various polishing techniques is overviewed, followed by the introduction of the research status of constant force control in robot-assisted polishing. Then, the errors in typical robot-assisted polishing systems are analyzed, together with the corresponding compensation methods. At last, the future trends in the development of robot-assisted polishing are discussed. This review is intended as a roadmap for researchers or engineers who are interested in robot-assisted polishing or machining.

An Innovative Approach of Surface Polishing for SRF Cavity Applications

The damage layer produced during the Niobium sheets and cavity fabrication processes is one of the main reasons why cavities have to undergo an extensive surface preparation process to recover optimal superconducting properties. Today, this includes the use of lengthy, costly, and dangerous conventional polishing techniques as buffered chemical polishing (BCP), or electro-polishing (EP). We propose to avoid or at least significantly reduce the use of acids. We developed a novel method based on metallographic polishing of Nb sheets, consisting of 2–3 steps. We demonstrate that this surface processing procedure could be transferred to large dimensions and an industrialized scale thanks to the limited number of steps and its compatibility with standard lapping polishing devices.

Effect of Optiglaze Coating on the Staphylococcus aurous and Porosity of Heat Cured Acrylic Material

Background: Polishing technique for acrylic resin material have great effect on properties of acrylic material and bacterial colonization such as staphylococcus aurous, which are responsible for many acrylic prosthetic infections such as the commonly ocular infections. Ineffective polishing technique could affect roughness and subsequently porosity of acrylic materials.So, a new effective method for polishing acrylic was used depending on the use of optiglaze coating material. So, this study aimed to evaluate the effect of optiglaze polishing on porosity of acrylic resin material and staphylococcus aurous activity in comparison to conventional polishing technique. &#x0D; Materials and methods: Specimen(n=120) were prepared :20 specimens constructed as circle shaped diameter 30mm with 1 mm thickness for porosity test (10 control polishing by conventional technique and 10 polishing by optiglaze technique). Other 82 specimens were prepared as circle specimen (6mm diameter and 1mm thickness) for sensitivity and adherences test ( each test have 20 specimens10 control and 10 optiglaze) and 42 specimens for viability test for three dilution,21 specimens for control and 21 for optiglaze (7 specimens for each dilution). Porosity were tested by light microscopic while agar well technique, adherence test and viability count test were tested for antibacterial activity of optiglaze against staphylococcus aurous.&#x0D; Result: The high mean value for porosity test was recorded by control while low mean value was recorded by optiglaze group with significant differences between them. Sensitivity and adherence test high mean value recorded by optiglaze with highly significant differences in comparison to control. Viability count test all dilution 10-7 ,10-6, 10-5 showed highly significant reduction in viability count of staphylococcus aurous by optiglaze group in comparison to control. Conclusion Polishing technique by Optiglaze significantly decrease porosity of acrylic resin and this method inhibited growth of staphylococcus aurous, and decrease its viable count (have antibacterial effect) but had less effect in adherence of this bacterial in comparison to control.

Magnetic field assisted finishing (MFAF) process for internal finishing of alumina ceramic tube

Nowadays, fine surface finish is in great demand for many industrial applications. An MFAF process is discussed in this conference paper to achieve a highly finished internal surface of non-ferromagnetic Alumina ceramic tube. Conventional grinding and polishing techniques cannot be used to finish this material because they cannot achieve high surface precision and produce surface defects like micro cracks. Therefore, MFAF process is an alternative method as it minimizes the surface damage because of flexible finishing conditions. MFAF Process, has flexible abrasive brush which can easily finish complex geometry of the workpiece. The workpiece material is alumina ceramic which is in higher demand as a substrate in electronic device applications. The MFAF process was done on alumina ceramic tube and 3 parameters, each having 2 different levels was selected. The parameters considered in the study are chuck speed (rpm), quantity of Diamond abrasive and iron power, machining time. 4 experiments with different levels of parameters were conducted. After finishing experiment using MINITAB 19 software, optimum parameters were determined. From the results of experiment, it was concluded that quantity of diamond abrasive and iron powder did not have much influence on finishing time compare to the chuck speed (r.p.m).

Efektivitas Teknik Air Abrasion dan Teknik Poles Konvensional Terhadap Perubahan Warna Pada Resin Komposit Nanofiller : kajian setelah proses perendaman kopi robusta (Laporan Penelitian)

Background: Nanofiller composite resins are commonly used as a restorative materials but nanofiller composite resins has high susceptibility to stain. Coffee has a huge impact on color changes. Besides of being able to give a smooth surface of a composite resins, polishing techniques were able to remove superficial stain on composite resins. Air abrasion technique has been introduced since 1945 and is still being used not because its only ability to remove caries, but also its ability to remove superficial stain on the teeth. Aim: to discover the effectiveness of air abrasion technique and conventional polishing technique towards color changes in nanofiller composite resins that were immersed in robusta coffee. Materials and Method: Twenty samples were immersed in robusta coffee for 7 days. Samples that have been stained were devided into two groups, group one were polished with air abrasion technique and group two were polished with conventional technique using abrasive discs.The color changes measurement were taken using spectrophotometer VITA Easyshade V prior to and after staining, and then repeated after polishing treatment. Result: There were significant differences in L, C and E between before the samples were immersed in robusta coffee and after they were polished with air abrasion technique. But there were no significant differences between before the samples were immersed in robusta coffee and after they were polished with conventional technique. Conclusion: There were differences in the effectiveness of air abrasion technique and conventional polishing technique towards color changes in nanofiller composite resins that were immersed in robusta coffee.

Novel insights on the study of a fifteenth-century oro di metà/Zwischgold gilding by means of ion and electron microscopy: characterization of the stratigraphy avoiding cross-sections preparation

Abstract In this work, an analytical methodology to identify and thoroughly characterize the oro di meta/Zwischgold gilding is reported. Gildings in paintings are commonly studied by means of optical microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectrometry (SEM-EDS), as well as other techniques, but they all require sample preparation. In this study, a sample of Zwischgold taken from an Italian panel painting of the fifteenth century was thoroughly characterized using Focused Ion Beam (FIB)-SEM sectioning, accessing the layered structure from the surface into depth without further sample preparation. The results achieved were compared to those of a further sample taken from the same area, which was prepared by conventional resin embedding and polishing techniques in order to evaluate the effects of the mechanical stresses induced by resin drying and polishing along the latter process. A more uniform morphology and sharper outlines of the metal layers were observed after FIB milling, likely due to the more accurate and less invasive cutting process. Moreover, since SEM-EDS analysis is limited in terms of resolution to be performed straight on the milled area relative to the thinness of the metal layers, Time of Flight – Secondary Ion Mass Spectrometry (ToF-SIMS) analysis was performed, and allowed revealing two distinct metal layers in the gilding consisting of Au and Ag thus confirming a Zwischgold structure.

EFFECT OF TWO POLISHING TECHNIQUES ON SURFACE ROUGHNESS OF THREE DIFFERENT DENTURE BASE MATERIALS (AN IN VITRO STUDY)

INTRODUCTION: A direct link was found between surface roughness, the accumulation of plaque and the adherence of microorganisms concerning acrylic resins. However, the surface properties of the new thermoplastic materials remain questionable especially after using the conventional finishing and polishing techniques. Studying surface properties of each material makes the recommendation of the proper techniques easier. OBJECTIVES: This in vitro study intended to compare three types of denture base materials in regarding to the effect of different polishing techniques on their surface roughness. MATERIALS AND METHODS: 36 specimens were incorporated in this study. 12 specimens were in each group. 3 groups were formed: Group A: Heat cured Polymethylmethacrylate (PMMA). Group B: Thermoplastic Polyamides. Group C: Thermoplastic Acetal. Dimensions of specimens were (20×20×3 mm) with projection at the side. Statistical analysis was carried out using two way analysis of variance (ANOVA). Statistical significance was defined at P≤0.05. RESULTS: Technique no. 1 showed a high significant value in compared to technique no.2 for polishing the tested materials. CONCLUSIONS: PMMA was the highest affected group followed by thermoplastic acetal and the last affected group was thermoplastic polyamide. Prepolishing rubberizing with rubber bur improves the polishing procedure. RESULTS: Remarkable improvement in the histology and the ultrastructure of the alveolar bone of rats in Group III was observed. Moreover, hematological values revealed significant decrease in the inflammatory condition of rats with induced RA after fish oil treatment. CONCLUSIONS: Rheumatoid arthritis is an important risk factor for alveolar bone loss. The treatment of the RA induced rats with fish oil not only prevented the alveolar bone resorption and stimulated new bone formation, but also reduced relatively the level of rheumatoid factor in the blood.

Fine Finishing of Extended Surfaces of 316 L Stainless Steel Thin Plate with Magnetic Abrasives

Some of the materials used in modern industries and industrial applications are difficult to finish with high degree of accuracy and minimal surface defects using conventional machining and polishing techniques. Stainless steel is one such widely used material that is ductile, tough and difficult to finish with traditional processes. This study aims to finish effectively the thin 316 L stainless steel plate using nontraditional technique as it is very difficult to finish using traditional technique. Response Surface Methodology approach for experimental design (Box-Behnken) is used for performing and analyzing the experimental work. Box-Behnken design is having the maximum efficiency for an experiment involving three factors and three levels. The experimental results indicate that the 316L stainless steel plate can be successfully finished with diamond sintered magnetic abrasives. The process yields best results of Rotational Speed = 200RPM, Feed = 40mm/sec and Machining Time = 60minutes for PISF. The PISF was improved by 45%.

Development of a magnetically driven abrasive polishing process for additively manufactured copper structures

Advances in manufacturing techniques have pushed the boundaries on many technological fronts such as semiconductor, biomedical, thermal management, and vacuum devices industries. Recent improvements in additive manufacturing have allowed the production of complex three-dimensional structures using polymers, metals, ceramics, or the combinations of these materials. However, surface roughness remains a critical bottleneck in these processes. High surface roughness limits the use of additively manufactured parts in applications requiring smooth surfaces. Various conventional polishing techniques have been used for additively manufactured external surfaces; however, polishing of enclosed surfaces, such as complex channel networks, still remains an unresolved issue. The goal of this study is to tackle the challenge of surface roughness in additively fabricated metal structures by developing a process that can polish external, as well as internal surfaces. Thus, a versatile process based on magneto-rheological fluid finishing is developed for this purpose. The process is developed and optimized using copper structures fabricated through electron beam melting. Preliminary polishing results show an immense improvement of surface roughness, reducing it from a mean surface roughness (Ra) of approximately 35µm and to 4µm.

Influence of surface sealant agents on the surface roughness and color stability of artificial teeth

Statement of problemAlthough various surface sealant agents are available and recommended for chairside polishing procedures, their effect on the surface roughness and color stability of denture teeth is not clear. PurposeThe purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of various denture tooth materials. Material and methodsEighty disk-shaped specimens were prepared for each type of denture tooth material (SR Vivodent, PMMA; Vitapan, reinforced-PMMA; SR Phonares II, composite resin). The specimens were assigned to 4 groups according to the surface treatment used (n=20): surface sealant agents (Palaseal; Heraeus Kulzer GmbH, Optiglaze; GC Corp Biscover; Bisco Inc) and a conventional laboratory polishing technique (control group). A thermal cycling procedure was applied for half of the specimens (n=10). The surface roughness (Ra) values of thermocycled and nonthermocycled specimens were measured with a profilometer. The CIELab color parameters of both thermocycled and nonthermocycled specimens were measured with a spectrophotometer at baseline and after 7-day storage in a coffee solution. The color differences were calculated from the CIEDE2000 (ΔE00) formula. Data were statistically analyzed with 3-way ANOVA and the Tukey HSD test (α=.05). ResultsThe type of tooth material, surface treatment technique, and their interactions were significant for Ra values, and each variable and their interactions were also significant for ΔE00 values (P<.05). Thermal cycling had a significant effect only on ΔE00 values (P<.05). ConclusionsPalaseal and Optiglaze sealant agents provided smoother and more color-stable denture tooth surfaces than the conventional polishing technique. The use of the Biscover agent with SR Vivodent and Phonares II teeth increased the Ra values. The color of conventionally polished SR Vivodent and Phonares II teeth changed more with thermal cycling.

Evaluation of the surface roughness of three heat-cured acrylic denture base resins with different conventional lathe polishing techniques: A comparative study.

Purpose:Surface roughness promotes adhesion and colonization of denture plaque. Therefore, it is important to know the effects of polishing and finishing on the surface roughness of various acrylic resin materials.Objectives:To evaluate and compare the effects of different conventional lathe polishing techniques on heat cured acrylic resins in producing surface roughness.Materials and Methods:Three different commercially available heat-cured acrylic resin materials namely DPI, Meliodent and Trevalon Hi were selected. 30 Specimens of each acrylic material (30 x 3 = 90, 10 x 60 x 2mm) were prepared and divided into 5 groups, each group consisted of 6 Nos. of specimens per material(6x3=18) and were grouped as Group A(unfinished), Group B (finished), Group C (Polishing Paste), Group D (Polishing Cake) and Group E (Pumice and Gold rouge). The resulted surface roughness (μm) was measured using Perthometer and observed under Scanning Electron Microscope. The values obtained were subjected statistical analyses.Results:Among the materials tested, better results were obtained with Trevalon Hi followed by Meliodent and DPI. Among the polishing methods used, superior results were obtained with universal polishing paste followed by polishing cake; Pumice and Gold rouge. Although Pumice and Gold rouge values produced greater roughness value, they were well within the threshold value of 0.2 mm.

Investigation of the effect of different polishing techniques on the surface roughness of denture base and repair materials

The rough surface of denture base materials may cause plaque accumulation and staining. Thus,theeffectiveness of polishing techniques should be known. The purpose of this study was to compare the effects of chairside polishing kits and conventional laboratory techniques on the surface roughness of denture base and repair materials. Ninety-six specimens, 50 ±1 mm in diameter and 0.5 ±0.05 thick, were fabricated from heat-polymerized acrylic resin (HP), polyamide resin (PR), and autopolymerizing resin (AP) and submitted to grinding with a tungsten carbide bur. The specimens were divided into 4 groups according to the polishing technique used: control group without polishing, conventional laboratory polishing, polished with Acrylic Polisher HP blue kit, and polished with AcryPoint polishing kit. Surface roughness (Ra) was measured after polishing with a profilometer. Data were analyzed with a 2-way analysis of variance, and the Tukey honestly significant difference (HSD) test was performed to identify significant differences (α=.05). The polishing techniques significantly affected the Ra of denture base materials (P<.001). The highest mean averageRa was measured for the control group. The lowest Ra values were determined in specimens exposed to conventional laboratory polishing techniques. No significant differences were found between Acrylic Polisher HP blue and AcryPoint polishing kits (P>.05). Statistically significant differences were found in the Ra between the PR and both the HP and AP (P<.001); PR exhibited the highest Ra values. Conventional laboratory polishing was the most effective polishing technique. A significantly smoother surfacethan that of the specimens in the control group was produced with chairside silicone polishing kits.

Effect of surface roughness on optical heating of metals

Heating by absorption of light is a commonly used technique to ensure a fast temperature increase of metallic samples. The rate of heating when using optical heating depends critically on the absorption of light by a sample. Here, the reflection and scattering of light from UV to IR by surfaces with different roughness of iron-based alloy samples (Fe, 1 wt-% Cr) is investigated. A combination of ellipsometric and optical scattering measurements is used to derive a simplified parametrisation which can be used to obtain the absorption of light from random rough metal surfaces, as prepared through conventional grinding and polishing techniques. By modelling the ellipsometric data of the flattest sample, the pseudodielectric function of the base material is derived. Describing an increased roughness by a Maxwell-Garnett model does not yield a reflectivity which follows the experimentally observed sum of scattered and reflected intensities. Therefore, a simple approach is introduced, based on multiple reflections, where the number of reflections depends on the surface roughness. This approach describes the data well, and is subsequently used to estimate the fraction of absorbed energy. Using numerical modelling, the effect on the heating rate is investigated. A numerical example is analysed, which shows that slight changes in roughness may result in big differences of the energy input into a metallic sample, with consequences on the achieved temperatures. Though the model oversimplifies reality, it provides a physically intuitive approach to estimate trends.

Reactive atom plasma (RAP) figuring machine for meter class optical surfaces

A new surface figuring machine called Helios 1200 is presented in this paper. It is designed for the figuring of meter sized optical surfaces with form accuracy correction capability better than 20 nm rms within a reduced number of iterations. Unlike other large figuring facilities using energy beams, Helios 1200 operates a plasma torch at atmospheric pressure, offers a high material removal rate, and a relatively low running cost. This facility is ideal to process large optical components, lightweight optics, silicon based and difficult to machine materials, aspheric, and free form surfaces. Also, the surfaces processed by the reactive atom plasma (RAP) are easy to fine polish through hand conventional sub-aperture polishing techniques. These unique combined features lead to a new capability for the fabrication of optical components opening up novel design possibilities for optical engineers. The key technical features of this large RAP machine are fast figuring capabilities, non-contact material removal tool, the use of a near Gaussian footprint energy beam, and a proven tool path strategy for the management of the heat transfer. Helios 1200 complies with the European machine safety standard and can be used with different types of reactive gases using either fluorine or chlorine compounds. In this paper, first the need for large optical component is discussed. Then, the RAP facility is described: radio frequency R.F generator, plasma torch, and 3 axis computer numerically controlled motion system. Both the machine design and the performance of the RAP tool is assessed under specific production conditions and in the context of meter class mirror and lens fabrication.

Deposition and friction properties of ultra-smooth composite diamond films on Co-cemented tungsten carbide substrates

To fabricate high-quality chemical vapor deposition (CVD) diamond coated tools or drawing dies, depositing adherent diamond films with fine surface morphology is essential. A novel deposition method combining conventional hot filament CVD (HFCVD) method and polishing technique is proposed, with which an ultra-smooth composite diamond (USCD) film consisting of a layer of fine-grained microcrystalline diamond (MCD) film and multiply layers of nanocrystalline diamond (NCD) films is deposited on Co-cemented tungsten carbide (WC-6 wt.% Co) substrate. The as-deposited USCD films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, X-ray diffraction (XRD) and Raman spectrum. Furthermore, Rockwell C indentation tests are conducted to evaluate the adhesion of the USCD film grown onto WC-Co substrate. The friction tests conducted on a ball-on-plate type reciprocating friction tester suggest that the fabricated USCD films exhibit very low friction coefficients of 0.129, 0.091 and 0.173 for dry sliding against ball-bearing steel, alumina ceramic and copper counterfaces respectively. With water lubricating, the friction coefficients of these three contacts further reduce to 0.057, 0.063 and 0.147.

High Efficient Finishing by Using a Structure-Controlled Polishing Pad (Improvement of Contact Condition Between Pad and Workpiece)

In loose-abrasive machining, a new polishing technique is required to be developed in order to finish a fragile workpiece such as thin silicon wafer or Low-k material and a hard material such as single-crystal SiC or sapphire. Namely, it is very difficult that high finishing efficiency is obtained in the above finishing using the conventional polishing technique. Then this paper deals with the achievement of high efficient finishing by using a structure-controlled polishing pad, which consists of a soft layer and a hard layer. The structure is thought to make the contact area between pad and workpiece expand with high polishing pressure. So it is expected to increase the number of the effective abrasives and the removal volume by a single abrasive. As a result of introducing it for finishing optical glass, high efficient finishing with lower load on workpiece was achieved, as compared with the conventional pads.

YBCO coated conductors prepared by chemical solution deposition: A TEM study

Recently large attention has been devoted to chemical solution deposition (CSD) as a promising method for fabricating low-cost YBCO coated conductors. We present an extensive transmission electron microscopy (TEM) cross-section analysis of CSD grown La 2Zr 2O 7 (LZO) buffer layers on flexible Ni–5at%W substrates. The high performance of these chemical solution derived buffer layers was confirmed by a YBCO critical current density J c of 0.84 MA/cm 2 achieved for a coated conductor sample with a layer sequence Ni–5at%W/LZO (CSD)/CeO 2 (CSD)/YBCO, where the YBCO film was deposited by pulsed laser deposition (PLD). TEM sample preparation was carried out by conventional mechanical polishing and ion milling techniques. TEM bright-field images of the LZO films and nickel substrates were acquired under two-beam conditions. The layer thicknesses and nanovoid size were determined for the LZO buffer layers. Moreover, the interfaces between the different layers were investigated and identified. Electron diffraction patterns were obtained in order to determine the microscopic texture of the samples. Despite the presence of nanovoids in the LZO buffer layers, they act as efficient Ni diffusion barriers.

Laser-Induced Fracturing: An Alternative to Mechanical Polishing and Patterning of&amp;lt;tex&amp;gt;$rm LiNbO_3$&amp;lt;/tex&amp;gt;Integrated Optics Chips

We report a method for cutting z-oriented LiNbO/sub 3/ substrates into nearly arbitrary shapes using a pulsed UV laser to controllably fracture the crystal. The end surfaces appear optically smooth. Ti-diffused waveguides terminated using this technique have fiber-waveguide-fiber insertion losses which are equal to the lowest values reported for waveguide end faces prepared using conventional mechanical polishing techniques.