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.

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 Path Optimization in 3D Concrete Printing to Minimize Weak Bonds Formation

2019 ◽  
Vol 50 (2) ◽  
pp. 163-168
Author(s):  
Fatima AlSakka ◽  
Mohammad Hasan Senan ◽  
Abdallah Abou Yassin ◽  
Farook Hamzeh
Keyword(s):  
Energy Use ◽  
Structural Integrity ◽  
Rupture Strength ◽  
Discrete Event ◽  
Cost Optimization ◽  
Printing Process ◽  
Event Simulation ◽  
3D Printed ◽  
Adhesion Level

3D concrete printing has proven to be a highly favorable construction method in terms of time reduction, cost optimization, architectural flexibility, sustainability, energy use, and others. However, the quality of the final product certainly has a priority over all of these attractive features of the technology. Yet research has given little consideration to investigating the structural integrity of 3D printed concrete structures. Research states that printed structures exhibit sufficient strength as compared to traditionally built structures. Nevertheless, the fact that this strength is sensitive to numerous factors including the machine setup, the printing process, existing conditions (e. g. temperature) and others, should be studied. A major determinant of the reliability and quality of printed structures is the adhesion level between subsequent layers. Poorly adhered concrete surfaces result in weak bonds that in turn reduce rupture strength. The time elapsed between printing successive concrete layers should be bounded to ensure that concrete is flowable enough to adhere to previous layers. For a given concrete mixture design, this time is a function of travel distance and speed. Thus, this research aims at finding the optimum printing path that minimizes the formation of weak bonds without compromising buildability for a given structure and a defined speed. The research employs Discrete Event Simulation to model the printing process for numerous possible travel paths and assess their adequacy by comparing travel time to allowable time limits.

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.

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.

The objective assessment of the quality of hospital care: dream or reality?

2007 ◽  
Vol 148 (43) ◽  
pp. 2033-2041
Author(s):  
Éva Belicza ◽  
Erika Takács
Keyword(s):  
Hospital Care ◽  
Objective Assessment

A nemzetközi szakirodalom egyre gyakrabban foglalkozik azzal a kérdéssel, hogy a minőségi indikátorokra támaszkodó nyilvános minőségértékelésnek mi a hatása az ellátás minőségére és az érintettek döntésére vonatkozóan, illetve melyek azok a kritériumok, amelyek mentén nyilvános minőségértékelési rendszereket célszerű kialakítani. A nemzetközi szakirodalom alapján a dolgozat hat témakört mutat be: (1) az indikátorok képessége a szolgáltatók megkülönböztetésére; (2) az eredményindikátorok alkalmassága a szolgáltatók megítélésére; (3) a bajnoki tabellák képessége a szolgáltatók rangsorolására; (4) a lakosság viselkedése a szolgáltatók választása során; (5) az indikátorokra támaszkodó nyilvános minősítések hatásai; (6) ajánlások minősítési rendszerek kidolgozására. A szakirodalmi kutatások szerint elsősorban a kockázatkiegyenlítési problémák miatt az indikátorok képessége a szolgáltatók megkülönböztetésére a nyújtott ellátás minősége szempontjából kérdéses; az elért ellátási eredmények nem feltétlenül utalnak vissza az ellátási folyamatok minőségére; a több indikátorból komponált intézményi sorrendek (bajnoki tabellák) nem megbízhatóak; a lakosság a szolgáltatók kiválasztásakor elsősorban a környezet véleményét és a távolságot veszi figyelembe; és a nyilvános közlések hatására igazoltan romlik az ellátás átfogó minősége. A szolgáltatók értékelésében alkalmazott mérési eredmények közzétételét eszköznek kell tekinteni. A lakosság intézményválasztásának elősegítésére az ő preferenciáik mentén végzett betegelégedettségi vizsgálatok nyilvánossá tétele hozhatja meg a kívánt eredményt. A minőségfejlesztési célokat igazoltan segítik a szolgáltatói körben végzett közvetlen visszajelzések az indikátorok mért értékeiről, illetve pontosabb kép kapható az ellátási és szervezési folyamatok, standardok egységes felülvizsgálatára alapozott eljárások külső értékelési rendszerekbe történő beemelésével.

Perilaku Birokrat Dalam Pelayanan Publik Di Distrik Asologaima Kabupaten Jayawijaya

2020 ◽  
Vol 12 (2) ◽  
pp. 93-100
Author(s):  
Yoel Tabuni
Keyword(s):  
Consumer Satisfaction ◽  
Rapid Development ◽  
Main Task ◽  
Government Administration ◽  
Following Instructions ◽  
District Government ◽  
The Times ◽  
Rule Governance ◽  
Descriptive Method

In line with the rapid development of the times and the increasingly complex problems faced by the state, there has also been a development in government administration which has been marked by a shift in the paradigm of governance from Rule Governance. This situation makes the bureaucracy rigid, in an environment that is only limited to flowing the instructions or following instructions. The district government in an Asologaima District has the main task of carrying out part of the authority delegated by the district head in the fields of government, economy, and development, society, peace, and order as well as coordination.The method is sed is descriptive method. Bureaucrats as providers of public services must be able to provide quality services, the quality of service of bureaucrats to society is closely related to customer satisfaction or consumer satisfaction as the recipient of the service itself.

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