Abrasive Disks Research Articles

Experimental study of grinding with a new body-armor-like abrasive disc for Ti-6Al-4V alloy

Experimental study of grinding with a new body-armor-like abrasive disc for Ti-6Al-4V alloy

A Comparative Analysis of Enamel Surface Roughness Following Various Interproximal Reduction Techniques: An Examination Using Scanning Electron Microscopy and Atomic Force Microscopy.

Interproximal enamel reduction (IER) is a minimally invasive therapeutic procedure commonly used in orthodontics to address both functional and aesthetic issues. Its mechanical effects on enamel surfaces induce the formation of grooves, furrows, scratches, depressions, and valleys. The aim of this study was to assess the enamel surface roughness resulting after the application of currently available methods for interproximal reduction. Ninety freshly extracted human teeth were divided into six groups and subjected to the stripping procedure, using a different method for each group (diamond burs, abrasive strips of 90 μm, 60 μm, 40 μm, 15 μm, and abrasive discs). A single individual performed stripping according to the manufacturer's recommendations, involving interproximal reduction on one tooth's proximal face and leaving the other side untreated. Qualitative and quantitative assessment of the enamel surfaces was carried out using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), obtaining 2D and volumetric 3D images of the enamel surface microstructure and nanostructure. The study found that diamond burs and abrasive strips of 60 μm and 90 μm increased enamel roughness due to intense de-structuring effects, while the 40 μm polisher had a gentler effect and 15 μm abrasive strips and polishing discs preserved enamel surface quality and removed natural wear traces.

Polishing methods for composites restoration: the influence on human gingival fibroblasts behaviour

BackgroundCarious/Non-carious cervical lesions with gingival recessions may require both dental and periodontal reconstructive therapy, where flaps/grafts may be placed in contact with a dental filling material. Human Gingival Fibroblasts (HGF-1) response during the early phase of healing could vary according to the procedures employed to cure the dental composite. Moreover, oxygen diffusion into dental composite inhibits the polymerization reaction, creating an oxygen-inhibited layer (OIL) that presents residual unreacted monomers. The aim of this study was to assess the effect of different polishing techniques and OIL on HGF-1.MethodsComposite discs polished with different techniques (diamond rubber, abrasive discs and tungsten carbide burr) were used. An additional not polished smooth group obtained with and without OIL was used as control. Samples were physically characterized through the analysis of their hydrophilicity and surface topography through contact angle measurement and SEM, respectively; afterwards the biologic response of HGF-1 when cultured on the different substrates was analyzed in terms of cytotoxicity and gene expression.ResultsThe finishing systems caused alterations to the wettability, even if without a proportional relation towards the results of the proliferation essay, from which emerges a greater proliferation on surfaces polished with one-step diamond rubber and with abrasive discs as well as a direct effect of the glycerin layer, confirming that surface roughness can heavily influence the biological response of HGF-1.ConclusionsSurfaces wettability as well as cellular behavior seem to be affected by the selection of the finishing system used to lastly shape the restoration. Especially, the presence of OIL act as a negative factor in the regards of human gingival fibroblasts. The present study may provide the first clinical instruction regarding the best polishing system of composite material when the restoration is placed directly in contact with soft tissue cells. Understanding HGF-1 behavior can help identifying the polishing treatment for direct restoration of carious/non-carious cervical lesions associated with gingival recessions.

Comparative Evaluation of Dental Enamel Microhardness Following Various Methods of Interproximal Reduction: A Vickers Hardness Tester Investigation.

Interproximal enamel reduction, also known as stripping, is a common orthodontic procedure that reduces the mesiodistal diameter of teeth, allowing for a balance of available space in dental arches. The aim of this study was to assess the enamel surface microhardness resulting from the application of currently available methods for interproximal reduction. Forty-two extracted human permanent teeth were divided into six different groups, each subjected to a therapeutic stripping procedure using various methods (i.e., diamond burs, abrasive strips of 90 μm, 60 μm, 40 μm, and 15 μm, and abrasive discs). Stripping was performed by a single individual in accordance with the manufacturers' recommendations for the various systems used. One of the proximal faces of the tooth underwent IPR, while the other side remained untreated for control. The hardness of the enamel surface was measured using a Vickers hardness tester. The control group achieved the hardest enamel surface (354.4 ± 41.02 HV1), while the lowest was observed for enamel surfaces treated with 90 µm abrasive strips (213.7 ± 118.6). The only statistically significant difference was identified in comparisons between the values measured for the control group and those obtained after stripping with diamond burs (p = 0.0159). Enamel microhardness varied depending on the stripping instrument used, but no statistically significant differences were found (p > 0.05). Optimal microhardness values, close to those of healthy enamel, were achieved after mechanical treatment with 15 µm abrasive strips and abrasive discs. Dental stripping is a safe therapeutic procedure that has a relatively minor influence on the microhardness of surface enamel.

Influence of SiO2–ZnO mixed soft abrasive on tribological behavior and polishing performance of sapphire wafer

The use of reactive soft abrasives, capable of undergoing solid-state reactions with sapphire, is a promising approach for low-damage and low-contamination machining of sapphire wafers. This study calculates the Gibbs free energy change of these chemical reactions based on thermodynamic principles. SiO2–ZnO mixed soft abrasives were selected for the polishing of sapphire wafers. Friction and wear experiments were conducted to explore the tribological behavior of sapphire wafers with various mixed abrasives, leading to the optimization of the abrasive composition. The results show that mixed abrasives significantly enhance the material removal rate (MRR) of sapphire wafers. As the proportion of SiO2 in the mixture increases, the MRR correspondingly rises. Specifically, an SiO2–to–ZnO ratio of 2:1 in the mixed abrasives results in a 91.68% increase in MRR compared to using SiO2 abrasives alone. Based on these findings, five grinding discs with different abrasive ratios were prepared using a resin binder for mechanical–chemical polishing experiments on sapphire wafers. The polishing results corroborate those of the friction and wear experiments, confirming that an increased SiO2 content in the mixed abrasive discs leads to higher MRR. With a 2:1 ratio of SiO2 to ZnO in the mixed abrasive disc, the MRR is enhanced by 342.9% compared to discs with only SiO2 abrasives, while reducing the surface roughness to 3.21 nm. In the SiO2–ZnO mixed abrasives, the inclusion of ZnO enhances chemical reactions during polishing. Aided by the mechanical removal efficacy of SiO2, this approach significantly increases MRR while maintaining superior polishing quality.

Research on the Features of Synchronous Cutting of Granite by Abrasive Water Jet and Disc Cutter

Research on the Features of Synchronous Cutting of Granite by Abrasive Water Jet and Disc Cutter

Research on Grinding Force Prediction of Flexible Abrasive Disc Grinding Process of TC17 Titanium Alloy

Abrasive disc grinding is currently a key manufacturing process to achieve better accuracy and high-quality surfaces of TC17 components. Grinding force, which results from the friction and elastic–plastic deformation during the contact and interaction between the abrasive grains and the workpiece, is a critical parameter that represents the grinding accuracy and efficiency. In order to understand the influence factors of grinding force, the characteristics of the flexible abrasive disc grinding process were studied. Considering the contact state between the abrasive tool and the workpiece, the theoretical model of normal grinding force was established in detail, from macro- and micro-perspectives. By conducting single-factor and orthogonal grinding experiments of TC17 components, the influence of different process parameters on the normal grinding force was revealed. The normal grinding force prediction models of the abrasive disc grinding process were developed based on the Box–Behnken design (BBD) and particle swarm optimization–back propagation (PSO-BP) neural networks, respectively. The results showed that the normal grinding force was negatively correlated with the disc rotational speed, and positively correlated with the contact angle, grinding depth, and feed rate, and the interaction of the factor feed rate and grinding depth was the more influential factor. Both the BBD and PSO-BP force models had good reliability and accuracy, and the mean absolute error (MAE) and mean relative error (MRE) of the above two prediction models were 0.22 N and 0.16 N, and 13.3% and 10.9%, respectively.

Surface quality evaluation through 3D profilometry of dental restoration performed in a clinical simulated environment

This study evaluated the surface quality of Class V composite resin restorations, comparing the surface roughness resulting from applying three techniques for finishing and polishing in a condition of clinical simulated environment by using artificial dental arcade. Beyond the aesthetic aspect, the importance of the surface quality of the restoration is associated with biofilm accumulation that occur on the teeth restored surface depending on the roughness level, leading to carious lesions and gingivitis. The minimum roughness considered ideal to avoid the accumulation of bacterial biofilm, is 0.2 μm, and 0.5 μm for tactile perception. Most of the evaluations of the surface quality of restorative materials are performed in flat specimens, and the results can significantly differ from the clinical scenario. The present work discloses how heterogeneous the surface quality may result when dealing with natural teeth. The finishing and polishing techniques selected in this work comprised diamond burs and rubber points, diamond burs and surface sealant, and abrasive discs, for restoring premolar natural teeth using a commercial composite resin. The surface quality of the restoration resulting from the three techniques was investigated through Ra, Rt, Rp, R, Rk, Rpk, Rvk and RSm roughness parameters, extracted from 3D topography maps. It was found that the use of abrasive discs (G3) promoted better surface quality, with mean Ra roughness near 0.4 μm, against 0.6 μm for the surface sealant group (G2) and 1.0 μm for the rubber points group (G1). It was evidenced that, together with Ra, analyses of roughness parameters regarding the proportion of peaks and valleys, in this case, Rp and Rpk, and roughness spacing, RSm, were significant to gain confidence and reveal reliable screening of the performance between the three techniques, with the best surface condition of the restored area resulting from the use of abrasive discs.

Influence of different finishing, aging with coffee, and repolishing protocols on the properties of nanoparticle composite resins.

Considering the variability of finishing protocols for composite resins, the literature does not offer a consensus about the influence of these approaches to obtain a final polishing and whether the physical properties of these composite resins change at different analysis times. Therefore, the study analyzed the microhardness, roughness, color stability, and gloss of a nanocomposite resin with different finishing, aging with coffee, and repolishing protocols. Nanocomposite resin samples were divided into three finishing protocol groups: Diamond burs (F and FF), multi-fluted tungsten carbide burs (18 and 30 flutes), and coarse and medium abrasive discs (Soflex-3M). All protocols used spiral rubber tips (F and FF) for polishing. Knoop microhardness (KHN), roughness (Ra), color changes (ΔE00 and YI), and gloss (GU) were analyzed. Scanning electron microscopy provided images of resins and finishing and polishing instruments. Resin KHN (p<0.001) decreased, and Ra (p<0.001), ΔE00 (p<0.001), and YI (p<0.001) increased after aging with coffee, regardless of finishing protocol. Abrasive discs showed lower color changes, YI, and Ra and higher GU. Repolishing restored KHN and Ra but not ΔE00 (p>0.05) and YI (p>0.05). Abrasive disc finishing reduced roughness and yellowness and increased nanocomposite resin gloss after aging with coffee. Key words:Color, Composite resins, Dental materials, Staining, Surface properties.

The development of laser cutting and drilling processes for thick Lithium Niobate wafers for electronic sensor applications

Lithium Niobate (LiNbO3) is a CVD grown synthetic salt having a trigonal crystal structure consisting of niobium, lithium, and oxygen. Due to its variety of mechanical and optical properties, single crystal LiNbO3 finds end use applications in optical waveguides, piezoelectric sensors, optical modulators, and electronic oscillators.LiNbO3 wafers are traditionally mechanically processed using abrasive disks and wire saws, and as a result of the inherently low fracture toughness cut-edge chipping and fracture occur lowering process yields. This study aimed to develop a laser process for the cutting, profiling and drilling of thick whole LiNbO3 wafers, using a femtosecond pulsed 515 nm wavelength source. The stresses induced during processing were controlled through a combination of wafer annealing, crystallographic (012) and (010) cleavage plane orientation. Process generated thermal gradients were controlled using beam manipulation and a water spray liquid flow process. The developed processes substantially reduced material fracture and significantly enhanced cut-edge quality, elevating yields above 80%.

Preparation of apricot kernel shell powder added polyester/calcium carbonate composite discs and investigation of their abrasive properties

Apricot kernel shell is suitable filler for abrasive materials with its strong, hard structure and dense cellulose content. Therefore, within the scope of this study, polyester composite (PE-CAC) discs containing apricot kernel shell powder were prepared in order to prepare abrasive polyester composite discs. In order to prevent these discs from damaging the surface on which they are applied during use, different amounts of calcium carbonate were added into the structure. The chemical structure of the obtained composite discs was confirmed by Fourier transform infrared spectroscopy. Surface morphology and structure were confirmed by scanning electron microscopy technique. The distribution of additives within the composite structures was examined by EDX spectroscopy. The effect of heat generated during the etching process on the composite disc structure was investigated using thermal analysis techniques. The added composite structures were transformed into cylindrical discs with a diameter of 45 mm and a height of 30 mm and were used to remove paint on metallic surfaces. As the amount of apricot kernel shell powder in the composite structure increases, the abrasion efficiency increases. Additionally, as the PE/CaCO3 composite disc application time increased, a significant decrease in surface roughness was observed. Ideal surface roughness was achieved, especially after 10 seconds of application time. As a result, PE/CaCO3 composite discs with apricot kernel additives present an important alternative to existing methods, especially in the cleaning of dirt, rust and paint on metallic surfaces.

Sample preparation and analysis protocols for the elucidation of structure and chemical distribution in kidney stones

Examining intact kidney stones both qualitatively and quantitatively can be difficult due to their size and fragility. Many modern analysis methods often lead to the destruction of the stone's structure during sample preparation. Preserving the structural integrity is crucial for accurately determining the chemical distribution of the components of kidney stones, which, in turn, improves our understanding of the disease's etiology. Infrared microspectroscopy and imaging play a vital role in revealing the stone's microstructure and component distribution. Consequently, this research focuses on investigating the impact of different sample preparation techniques on kidney stone analysis using infrared microspectroscopy. Specifically, it explores how polishing the surface of cross-sectioned stones influences the results. The polishing was performed utilizing abrasive discs and lapping films. A polishing device was also designed for the optimization of sample preparation. Additionally, this work involved a comparison of reflection infrared imaging with Attenuated Total Internal Reflection (ATR) infrared microspectroscopic imaging for the analysis of the microstructure of urinary stones.

Analysis of nano grinding removal mechanism of 3C-SiC material under the coupling action of double abrasive grains

In order to study the influence mechanism of coupling effect on 3C-SiC material removal process under nanometer conditions, the repeated scratches of different abrasive grains, machined surface morphology, dislocation distribution, grinding force and abrasive wear were analyzed by molecular dynamics method, and the geometric characteristics and damage distribution of machined surface under the coupling effect of dual abrasive grains, as well as the influence rule of coupling effect on surface/subsurface characteristics were obtained. This study is of great significance to understand the mechanism of 3C-SiC removal in nano-scale grinding process, and is helpful to guide the preparation of fixed abrasive polishing discs.

Development and characterization of agglomerated abrasives based on agro-industrial by-products

ABSTRACT The present work deals with the valorization of agro-industrial by-products to realize bonded abrasives. Four by-products were studied because of their wide availability and mechanical properties: palm nuts shells (Elaeis guineensis), Coco Nucifera shells, fruit kernels of Canarium schweinfurthii and fruit kernels of Raffia Vinifera. The Oliver and Pharr hardness and Young’s modulus of the raffia cores are obtained by instrumented macro indentation, giving the values 101 MPa and 1.82 GPa, respectively. The development of the abrasive wheels was based on the experimental method of full factorial design at 2 levels. Porosity, hardness, resilience, material removal rate and wear were determined. Leeb 280 HL hardness shoe sole material was used for tribological testing. The optimal formulations have 20% binder content and 1 mm grain size of the four agro-industrial by-products used with a higher material removal rate and a longer life than commercial grinding wheels. These results presage their use in the shoe industry and abrasive disc huskers.

Surface smoothness of resin composites after polishing-A systematic review and network meta-analysis of in vitro studies.

A systematic review and network meta-analysis was performed to provide evidence for the best polishing protocol for different types of resin composites to minimize surface roughness. A search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, EMBASE, and Cochrane Library on July 2, 2019 (updated in December, 2020). In vitro studies that included at least two systems for polishing resin composites and analyzed surface roughness were included. The risk of bias was evaluated. A random-effects Bayesian-mixed treatment comparison model was used to compare surface roughness in resin composites with the different types of polishers. Surface under the cumulative ranking curve (SUCRA) analysis was performed to rank the probability for the best polishing system. After removal of duplicates, title and abstract screening yielded 34 studies. Network meta-analysis was not possible for hybrid and microhybrid composites. SUCRA analysis showed that abrasive paper discs allowed greater surface smoothness for nanohybrid and nanofill composites to a probability of between 83% and 91.6%. Silicon carbide brush had a 78.2% probability of being the best system for microfill composites. The use of abrasive paper disc polishers showed a favorable result in nanofill and nanohybrid resin composites. Silicon carbide brush has a greater chance of promoting a smoother surface for microfill resin composites.

Contact Characteristics and Material Removal Mechanism of Abrasive Disc Grinding of Aero-engine Blade

Contact Characteristics and Material Removal Mechanism of Abrasive Disc Grinding of Aero-engine Blade

Influence of technical and technological parameters on the barley dehulling process

Introduction. The research aim is to determine effect of duration of dehulling, the barley size and moisture, the rotation speed of abrasive discs, the abrasive grit and the load factor of the dehuller on the dehulling index. Materials and methods. The dehulling was carried out in laboratory dehuller (model ULZ-1) at the rotation speed of abrasive discs of 29.6±0.015 s-1 (1775±0.9 rpm) and 42.3±0.013 s-1 (2540±0.8 rpm) and removing of barley husks and meal was conducted in the laboratory aspiration duct of 60 mm width. Results and discussion. The research has shown that the increase in the dehulling duration the weight of the barley loaded to the dehuller, the rotating rate of abrasive discs and the load coefficient of the dehuller working chamber leads to the dehulling index rise. There exists the non-linear dependence between the load coefficient of the dehuller working chamber with the minimum point of the dehulling index for the large fraction of barley 0.27–0.28 and for the small fraction of barley 0.24–0.25. The influence of the barley weight and the load coefficient of the working chamber of the dehuller on the dehulling index occurs according to the curvilinear dependence with the minimum point of the dehulling index for the large barley fraction of 0.27–0.28 and for the small barley fraction of 0.24–0.25. The increase in the processing duration and the load coefficient of the working chamber of the dehuller leads to the increase of the dehulling index, but at the same time the minimum point of the dehulling index decreases from 0.29 to 0.25. As the size of the barley grows, the dehulling index decreases. The gain in moisture of the barley leads to the decrease of the dehulling index according to the linear dependence for both large and small barley fractions. Moreover, the small fraction has the bigger values of the dehulling index than the large one. The moisture influence on the dehulling index has linear dependence for both large and small barley fractions. As moisture increases the dehulling index decreases linearly, but at the same time the large barley fraction had lower values of the dehulling index than the small one. The increase in abrasive discs grit leads to the dehulling index decrease according to the curvilinear dependence. At the grit of 80 the dehulling index gets the constant value and its change depends on the duration of processing. Conclusion. The influence of technological parameters of barley grain on the dehulling index has linear dependence, and machine parameters affect the dehulling index according to curvilinear dependency. These results must be considered when evaluating the effectiveness of dehulling and the development of the process model.

The Effect of Additional Finishing and Polishing Sequences on Hardness and Roughness of Two Different Dental Composites: An In Vitro Study

Aim: The aim of this study was to evaluate the effect of additional finishing and polishing sequences on a new structural colored (Omnichroma) and a conventional dental composite (Estelite Sigma Quick). Materials and Method: Forty disk-shaped dental composite specimens were prepared from each dental composite and assigned to four groups in terms of additional finishing polishing sequences. Group 1: Mylar strip (control). Group 2: Abrasive disks. Group 3: After abrasive disks, application of a felt brush with abrasive paste. Group 4: After abrasive disks, application of a felt brush with abrasive paste. Then, a single-bottle adhesive was applied as a surface sealer. Hardness and surface roughness were measured using the Vickers hardness test and a profilometer, respectively. SEM images of one of each group were captured at 500x, 1500x, and 3500x magnifications. Two-way analysis of variance, Tukey HSD, and Shapiro–Wilk tests were used for the statistical analysis. Results: Mean hardness values differ in terms of finishing-polishing sequences ( P &lt; .001), dental composites ( P &lt; .001), and interaction of finishing-polishing sequences-dental composites ( P &lt; .001). Mean roughness values differ in terms of finishing-polishing ( P = .002). The main effect of composites on roughness values was not found statistically significant ( P = .990). Also, there is no difference between the mean roughness values in terms of the interactions of finishing-polishing and composites ( P = .967). Conclusion: Finishing-polishing with abrasive disks and abrasive paste are important steps for these dental composites. However, the application of a single-bottle adhesive as a surface sealant on these composites decreases the hardness of the materials.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro.

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3× with 1× PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

Abrasion Resistance of Plastic Parts Manufactured By 3D Printing

Abstract There are situations where parts manufactured by 3D printing processes must have a high abrasion resistance. To conduct experimental research on this subject, relatively simple test equipment for abrasive wear of pin-on-disk type was designed and materialized. The test pieces from the research material were pressed with known forces on the surface of a rotating abrasive paper disk. The test pieces were made of polyethylene terephthalate PET and polyethylene terephthalate carbon fiber reinforced PET CF15. As output parameters, the speed of decreasing the mass and the length of the test piece were used, respectively, for predetermined test durations. An experimental Taguchi L8 program was used, with 7 independent variables at two levels of variation. The experimental results were mathematically processed determined empirical mathematical models of the power function type. It was found that the strongest influence on the values of the output parameters was exerted by the average travel speed and by the granulation of the particles incorporated in the abrasive paper disk.