scholarly journals Sliding behaviour and surface quality after static air polishing of conventional and modern bracket materials

2021 ◽  
Author(s):  
Lutz Hodecker ◽  
Christoph Bourauel ◽  
Bert Braumann ◽  
Teresa Kruse ◽  
Hildegard Christ ◽  
...  
Keyword(s):  
Surface Quality ◽  
Structural Defects ◽  
Dental Calculus ◽  
Air Polishing ◽  
Tooth Cleaning ◽  
Effective Reduction ◽  
Noticeable Improvement ◽  
Ceramic Brackets ◽  
3D Printed

Abstract Objectives As part of orthodontic treatment, air polishing is routinely used for professional tooth cleaning. Thus, we investigated the effects of static powder polishing on sliding behaviour and surface quality of three different bracket materials (polymer, ceramic, metal), including a 3D-printed bracket. Methods Two bracket types of each material group were polished with an air-polishing device using sodium bicarbonate. Exposure times were set at 10, 20, and 60 s; the application distance was 5 mm. The force loss due to sliding resistance was tested with an orthodontic measurement and simulation system (OMSS) using a 0.016 inch × 0.022 inch stainless steel archwire. Untreated brackets served as control. Polishing effects and slot precision were evaluated using an optical digital and scanning electron microscope. Results Sliding behaviour and slot precision differed significantly between and within the groups. Prior to polishing, polymer brackets showed the least force loss, ceramic brackets the highest. With progressive polishing time, the resistance increased significantly with titanium brackets (26 to 37%) and decreased significantly with steel brackets (36 to 25%). Polymer brackets showed the smallest changes in force loss with respect to polishing duration. Slot precision showed the largest differences between material groups and was primarily manufacturer-dependent with hardly any changes due to the polishing time. Conclusion Powder polishing can positively or negatively affect the sliding properties of the bracket–archwire complex but is more dependent on the bracket–archwire material combination (i.e., manufacture-dependent slot precision). For titanium brackets, resistance only increased after 60 s of polishing. For ceramic brackets, effective reduction was observed after 10 s of polishing. Polymer brackets, including the 3D-printed brackets, showed better sliding properties than ceramic or metal brackets even after polishing for 60 s. Removal of plaque and dental calculus should lead to a noticeable improvement of the sliding properties and outweighs structural defects that may develop.

scholarly journals Impact of Structural Defects on the Surface Quality of Hardwood Species Sliced Veneers

2020 ◽  
Vol 10 (18) ◽  
pp. 6265
Author(s):  
Vasiliki Kamperidou ◽  
Efstratios Aidinidis ◽  
Ioannis Barboutis
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Wood Species ◽  
Research Work ◽  
Structural Defects ◽  
Material Surface ◽  
Typical Structure ◽  
Hardwood Species ◽  
The Impact

The surface roughness constitutes one of the most critical properties of wood and wood veneers for their extended utilization, affecting the bonding ability of the veneers with one another in the manufacturing of wood composites, the finishing, coating and preservation processes, and the appearance and texture of the material surface. In this research work, logs of five significant European hardwood species (oak, chestnut, ash, poplar, cherry) of Balkan origin were sliced into decorative veneers. Their surface roughness was examined by applying a stylus tracing method, on typical wood structure areas of each wood species, as well as around the areas of wood defects (knots, decay, annual rings irregularities, etc.), to compare them and assess the impact of the defects on the surface quality of veneers. The chestnut veneers presented the smoothest surfaces, while ash veneers, despite the higher density, recorded the highest roughness. In most of the cases, the roughness was found to be significantly lower around the defects, compared to the typical structure surfaces, probably due to lower porosity, higher density and the presence of tensile wood. The results reveal that the presence of defects does not affect the roughness of the veneers and increases neither the processing requirements of the veneer sheets before finishing, nor the respective production cost of veneers and the veneer-based wood panels. The high utilization prospects of the examined wood species in veneer production, even those bearing various defects, is highlighted.

scholarly journals Surface Finishing of FDM-Fabricated Amorphous Polyetheretherketone and Its Carbon-Fiber-Reinforced Composite by Dry Milling

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2175
Author(s):  
Cheng Guo ◽  
Xiaohua Liu ◽  
Guang Liu
Keyword(s):  
Carbon Fiber ◽  
Layer Thickness ◽  
Surface Quality ◽  
Feed Rate ◽  
Depth Of Cut ◽  
Dry Milling ◽  
Staircase Effect ◽  
Raster Angle ◽  
3D Printed

In recent years, many investigations have been devoted to fused deposition modeling (FDM) of high-performance polymer-polyetheretherketone (PEEK) and carbon-fiber-reinforced PEEK (CF/PEEK) for biomedical and aerospace applications. However, the staircase effect naturally brought about by FDM restricts further applications of 3D-printed PEEK and its composites in high-temperature molds, medical implants, and precision components, which require better or customized surface qualities. Hence, this work aimed to reduce the staircase effect and improve the surface quality of 3D-printed PEEK and CF/PEEK parts by dry milling of the fluctuant exterior surface. The co-dependency between 3D printing parameters (raster angle and layer thickness) and milling parameters (depth of cut, spindle speed, and feed rate per tooth) were investigated through experiments. The difference in removal mechanisms for PEEK and CF/PEEK was revealed. It was confirmed that the smearing effect enhanced the surface quality based on the morphology analysis and the simulation model. Both the raster angle of +45°/−45° and the small layer thickness could improve the surface quality of these 3D-printed polymers after dry milling. A large depth of cut and a large feed rate per tooth were likely to deteriorate the finished polymer surface. The spindle speed could influence the morphologies without significant changes in roughness values. Finally, a demonstration was performed to verify that dry milling of 3D-printed amorphous PEEK and CF/PEEK parts could lead to a high surface quality for critical requirements.

scholarly journals Objective 3D Printed Surface Quality Assessment Based on Entropy of Depth Maps

Entropy ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 97 ◽  
Author(s):  
Jarosław Fastowicz ◽  
Marek Grudziński ◽  
Mateusz Tecław ◽  
Krzysztof Okarma
Keyword(s):  
Surface Quality ◽  
Rapid Development ◽  
Objective Assessment ◽  
Printing Process ◽  
Depth Maps ◽  
3D Scanners ◽  
3D Printed ◽  
3D Scans ◽  
Time And Energy

A rapid development and growing popularity of additive manufacturing technology leads to new challenging tasks allowing not only a reliable monitoring of the progress of the 3D printing process but also the quality of the printed objects. The automatic objective assessment of the surface quality of the 3D printed objects proposed in the paper, which is based on the analysis of depth maps, allows for determining the quality of surfaces during printing for the devices equipped with the built-in 3D scanners. In the case of detected low quality, some corrections can be made or the printing process may be aborted to save the filament, time and energy. The application of the entropy analysis of the 3D scans allows evaluating the surface regularity independently on the color of the filament in contrast to many other possible methods based on the analysis of visible light images. The results obtained using the proposed approach are encouraging and further combination of the proposed approach with camera-based methods might be possible as well.

A study on the surface quality of the 3D printed parts caused by the scanning strategy

2019 ◽  
Vol 25 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Jitai Han ◽  
Yanan Ge ◽  
Yuxin Mao ◽  
Meiping Wu
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Scanning Strategy ◽  
Clear Trend ◽  
Content Type ◽  
3D Printed ◽  
Side Face ◽  
Zigzag Shape ◽  
The Relationship

Purpose The purpose of this paper is to mainly focus on the relationship between the scanning strategy and surface quality. Surface quality, including surface roughness and flatness, is important for printed parts. So this paper optimizes the surface quality by changing the scanning strategy. Design/methodology/approach This paper is based on the phenomenon after the printed parts. A clear trend can be seen that the surface roughness on the side face shows a clear zigzag shape, so an optimized scanning strategy is used. Surface roughness in measured in macrostructure first by Mitutoyo and the flatness is measured by Hexagon Metrocogy. After that, microstructure on the side face is seen by RTEC to explain this phenomenon. Findings The surface quality on the side face shows a significant optimize by changing the scanning strategy. The surface quality on the positive face has some optimization to some degree. Originality/value This paper determines the relationship between the surface roughness on the side face and the scanning strategy. Few studies focus on the surface roughness, especially on the side face. Some studies try to optimize the surface roughness on the positive face. However, researchers always neglect the surface roughness on the side face. 2. This paper measures not only the surface roughness, but also the flatness. Surface roughness has a significant impact on the surface quality. However, it still has some limitations. Flatness is also measured to make this paper more representative. 3. This paper explains why scanning strategy can affect the surface quality. These images explain the research better and not just at the theoretical level.

Schwingungsüberlagertes Axialformen/Superimposed Oscillated Axial Forming

2020 ◽  
Vol 110 (11-12) ◽  
pp. 838-843
Author(s):  
Philipp Müller ◽  
Bernd-Arno Behrens ◽  
Sven Hübner ◽  
Hendrik Vogt ◽  
Daniel Rosenbusch ◽  
...  
Keyword(s):  
Surface Quality ◽  
Economic Importance ◽  
Combined Effect ◽  
Wird Eine ◽  
Forming Force ◽  
Forming Process ◽  
Forming Technology ◽  
Great Economic Importance ◽  
Gear Geometry

Techniken zur Steigerung der Formgebungsgrenzen in der Umformtechnik sind von hoher wirtschaftlicher Bedeutung. In dieser Arbeit wird eine Schwingungsüberlagerung im Krafthauptfluss eines Axialformprozesses zur Ausprägung einer Verzahnungsgeometrie untersucht. Die Auswirkungen der Schwingung auf die erzielbare Ausfüllung der Zahnkavitäten werden analysiert sowie die Parameter Schmierung und Oberflächengüte der Halbzeuge in ihrer kombinierten Wirkung untersucht. Es konnte eine Reduzierung der mittleren Umformkraft sowie eine Erhöhung der Formfüllung festgestellt werden. Techniques for extending the production limits in forming technology are of great economic importance. In this research, a superimposed oscillation in the main force flow of an axial forming process to form an axial gear geometry is investigated. The effects of the superimposed oscillation on the achievable form-filling of the tooth cavities are analyzed and the parameters lubrication and surface quality of the semi-finished products are investigated in their combined effect. A reduction of the averaged forming force as well as an increase of the form-filling could be achieved.

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