The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Kuglaur Shanmugam Ranjith - One of the best experts on this subject based on the ideXlab platform.
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Nanograined surface Shell Wall controlled ZnO–ZnS core–Shell nanofibers and their Shell Wall thickness dependent visible photocatalytic properties
Catalysis Science & Technology, 2020Co-Authors: Kuglaur Shanmugam Ranjith, Anitha Senthamizhan, Brabu Balusamy, Tamer UyarAbstract:The core–Shell form of ZnO–ZnS based heterostructural nanofibers (NF) has received increased attention for use as a photocatalyst owing to its potential for outstanding performance under visible irradiation. One viable strategy to realize the efficient separation of photoinduced charge carriers in order to improve catalytic efficiency is to design core–Shell nanostructures. But the Shell Wall thickness plays a vital role in effective carrier separation and lowering the recombination rate. A one dimensional (1D) form of Shell Wall controlled ZnO–ZnS core–Shell nanofibers has been successfully prepared via electrospinning followed by a sulfidation process. The ZnS Shell Wall thickness can be adjusted from 5 to 50 nm with a variation in the sulfidation reaction time between 30 min and 540 min. The results indicate that the surfaces of the ZnO nanofibers were converted to a ZnS Shell layer via the sulfidation process, inducing visible absorption behavior. Photoluminescence (PL) spectral analysis indicated that the introduction of a ZnS Shell layer improved electron and hole separation efficiency. A strong correlation between effective charge separation and the Shell Wall thickness aids the catalytic behavior of the nanofiber network and improves its visible responsive nature. The comparative degradation efficiency toward methylene blue (MB) has been studied and the results showed that the ZnO–ZnS nanofibers with a Shell Wall thickness of ∼20 nm have 9 times higher efficiency than pristine ZnO nanofibers, which was attributed to effective charge separation and the visible response of the heterostructural nanofibers. In addition, they have been shown to have a strong effect on the degradation of Rhodamine B (Rh B) and 4-nitrophenol (4-NP), with promising reusable catalytic efficiency. The Shell layer upgraded the nanofiber by acting as a protective layer, thus avoiding the photo-corrosion of ZnO during the catalytic process. A credible mechanism for the charge transfer process and a mechanism for photocatalysis supported by trapping experiments in the ZnO–ZnS heterostructural system for the degradation of an aqueous solution of MB are also explicated. Trapping experiments indicate that h+ and ˙OH are the main active species in the ZnO–ZnS heterostructural catalyst, which do not effectively contribute in a bare ZnO catalytic system. Our work also highlights the stability and recyclability of the core–Shell nanostructure photocatalyst and supports its potential for environmental applications. We thus anticipate that our results show broad potential in the photocatalysis domain for the design of a visible light functional and reusable core–Shell nanostructured photocatalyst.
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effective Shell Wall thickness of vertically aligned zno zns core Shell nanorod arrays on visible photocatalytic and photo sensing properties
Applied Catalysis B-environmental, 2018Co-Authors: Kuglaur Shanmugam Ranjith, Rutely Burgos Castillo, Mika Sillanpaa, Ramaswamy Thangavelu Rajendra KumarAbstract:Abstract Development of hierarchical core-Shell semiconductor heterostructures ensue significant advancement in catalytic functional structures with improvised optical functionalities. Shell Wall controlled vertically aligned ZnO-ZnS core-Shell nanorod (NR) heterostructures were grown on transparent conductive substrates along the c-axis by sulfidation of aligned ZnO nanorod arrays for visible photocatalytic properties. The effects of the sulfidation time on the morphology, crystalline properties, optical property, photocurrent response, and photocatalytic activity of the catalyst arrays were studied under UV and visible light irradiation. The Shell Wall thickness of these heterostructures influenced in great extent the effective photo responsive charge separation and improved carrier mobility. ZnO-ZnS core-Shell heterostructure having the Shell Wall thickness of 20 nm has exhibited more efficient visible photocatalytic behavior due to effective separation of carriers and improved visible absorption. On further increasing the Wall thickness the catalytic efficiency was reduced due to the poor carrier (hole) mobility in the polycrystalline Shell grains which induced the higher recombination rate. Stability and reusability of ZnO-ZnS core-Shell nanostructures reveals that the ZnS acted as a protective layer over the ZnO NR arrays. In appraisal with ZnO NR arrays, the control over the Shell Wall thickness of ZnO-ZnS core-Shell NR array attributed to the excellent visible photocatalytic activity and improvised absorption of light in visible region at ZnO-ZnS interface and effective separation of photogenerated electron-hole pairs at ZnO-ZnS heterojunctions.
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nanograined surface Shell Wall controlled zno zns core Shell nanofibers and their Shell Wall thickness dependent visible photocatalytic properties
Catalysis Science & Technology, 2017Co-Authors: Kuglaur Shanmugam Ranjith, Anitha Senthamizhan, Brabu Balusamy, Tamer UyarAbstract:The core–Shell form of ZnO–ZnS based heterostructural nanofibers (NF) has received increased attention for use as a photocatalyst owing to its potential for outstanding performance under visible irradiation. One viable strategy to realize the efficient separation of photoinduced charge carriers in order to improve catalytic efficiency is to design core–Shell nanostructures. But the Shell Wall thickness plays a vital role in effective carrier separation and lowering the recombination rate. A one dimensional (1D) form of Shell Wall controlled ZnO–ZnS core–Shell nanofibers has been successfully prepared via electrospinning followed by a sulfidation process. The ZnS Shell Wall thickness can be adjusted from 5 to 50 nm with a variation in the sulfidation reaction time between 30 min and 540 min. The results indicate that the surfaces of the ZnO nanofibers were converted to a ZnS Shell layer via the sulfidation process, inducing visible absorption behavior. Photoluminescence (PL) spectral analysis indicated that the introduction of a ZnS Shell layer improved electron and hole separation efficiency. A strong correlation between effective charge separation and the Shell Wall thickness aids the catalytic behavior of the nanofiber network and improves its visible responsive nature. The comparative degradation efficiency toward methylene blue (MB) has been studied and the results showed that the ZnO–ZnS nanofibers with a Shell Wall thickness of ∼20 nm have 9 times higher efficiency than pristine ZnO nanofibers, which was attributed to effective charge separation and the visible response of the heterostructural nanofibers. In addition, they have been shown to have a strong effect on the degradation of Rhodamine B (Rh B) and 4-nitrophenol (4-NP), with promising reusable catalytic efficiency. The Shell layer upgraded the nanofiber by acting as a protective layer, thus avoiding the photo-corrosion of ZnO during the catalytic process. A credible mechanism for the charge transfer process and a mechanism for photocatalysis supported by trapping experiments in the ZnO–ZnS heterostructural system for the degradation of an aqueous solution of MB are also explicated. Trapping experiments indicate that h+ and ˙OH are the main active species in the ZnO–ZnS heterostructural catalyst, which do not effectively contribute in a bare ZnO catalytic system. Our work also highlights the stability and recyclability of the core–Shell nanostructure photocatalyst and supports its potential for environmental applications. We thus anticipate that our results show broad potential in the photocatalysis domain for the design of a visible light functional and reusable core–Shell nanostructured photocatalyst.
Tamer Uyar - One of the best experts on this subject based on the ideXlab platform.
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Nanograined surface Shell Wall controlled ZnO–ZnS core–Shell nanofibers and their Shell Wall thickness dependent visible photocatalytic properties
Catalysis Science & Technology, 2020Co-Authors: Kuglaur Shanmugam Ranjith, Anitha Senthamizhan, Brabu Balusamy, Tamer UyarAbstract:The core–Shell form of ZnO–ZnS based heterostructural nanofibers (NF) has received increased attention for use as a photocatalyst owing to its potential for outstanding performance under visible irradiation. One viable strategy to realize the efficient separation of photoinduced charge carriers in order to improve catalytic efficiency is to design core–Shell nanostructures. But the Shell Wall thickness plays a vital role in effective carrier separation and lowering the recombination rate. A one dimensional (1D) form of Shell Wall controlled ZnO–ZnS core–Shell nanofibers has been successfully prepared via electrospinning followed by a sulfidation process. The ZnS Shell Wall thickness can be adjusted from 5 to 50 nm with a variation in the sulfidation reaction time between 30 min and 540 min. The results indicate that the surfaces of the ZnO nanofibers were converted to a ZnS Shell layer via the sulfidation process, inducing visible absorption behavior. Photoluminescence (PL) spectral analysis indicated that the introduction of a ZnS Shell layer improved electron and hole separation efficiency. A strong correlation between effective charge separation and the Shell Wall thickness aids the catalytic behavior of the nanofiber network and improves its visible responsive nature. The comparative degradation efficiency toward methylene blue (MB) has been studied and the results showed that the ZnO–ZnS nanofibers with a Shell Wall thickness of ∼20 nm have 9 times higher efficiency than pristine ZnO nanofibers, which was attributed to effective charge separation and the visible response of the heterostructural nanofibers. In addition, they have been shown to have a strong effect on the degradation of Rhodamine B (Rh B) and 4-nitrophenol (4-NP), with promising reusable catalytic efficiency. The Shell layer upgraded the nanofiber by acting as a protective layer, thus avoiding the photo-corrosion of ZnO during the catalytic process. A credible mechanism for the charge transfer process and a mechanism for photocatalysis supported by trapping experiments in the ZnO–ZnS heterostructural system for the degradation of an aqueous solution of MB are also explicated. Trapping experiments indicate that h+ and ˙OH are the main active species in the ZnO–ZnS heterostructural catalyst, which do not effectively contribute in a bare ZnO catalytic system. Our work also highlights the stability and recyclability of the core–Shell nanostructure photocatalyst and supports its potential for environmental applications. We thus anticipate that our results show broad potential in the photocatalysis domain for the design of a visible light functional and reusable core–Shell nanostructured photocatalyst.
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nanograined surface Shell Wall controlled zno zns core Shell nanofibers and their Shell Wall thickness dependent visible photocatalytic properties
Catalysis Science & Technology, 2017Co-Authors: Kuglaur Shanmugam Ranjith, Anitha Senthamizhan, Brabu Balusamy, Tamer UyarAbstract:The core–Shell form of ZnO–ZnS based heterostructural nanofibers (NF) has received increased attention for use as a photocatalyst owing to its potential for outstanding performance under visible irradiation. One viable strategy to realize the efficient separation of photoinduced charge carriers in order to improve catalytic efficiency is to design core–Shell nanostructures. But the Shell Wall thickness plays a vital role in effective carrier separation and lowering the recombination rate. A one dimensional (1D) form of Shell Wall controlled ZnO–ZnS core–Shell nanofibers has been successfully prepared via electrospinning followed by a sulfidation process. The ZnS Shell Wall thickness can be adjusted from 5 to 50 nm with a variation in the sulfidation reaction time between 30 min and 540 min. The results indicate that the surfaces of the ZnO nanofibers were converted to a ZnS Shell layer via the sulfidation process, inducing visible absorption behavior. Photoluminescence (PL) spectral analysis indicated that the introduction of a ZnS Shell layer improved electron and hole separation efficiency. A strong correlation between effective charge separation and the Shell Wall thickness aids the catalytic behavior of the nanofiber network and improves its visible responsive nature. The comparative degradation efficiency toward methylene blue (MB) has been studied and the results showed that the ZnO–ZnS nanofibers with a Shell Wall thickness of ∼20 nm have 9 times higher efficiency than pristine ZnO nanofibers, which was attributed to effective charge separation and the visible response of the heterostructural nanofibers. In addition, they have been shown to have a strong effect on the degradation of Rhodamine B (Rh B) and 4-nitrophenol (4-NP), with promising reusable catalytic efficiency. The Shell layer upgraded the nanofiber by acting as a protective layer, thus avoiding the photo-corrosion of ZnO during the catalytic process. A credible mechanism for the charge transfer process and a mechanism for photocatalysis supported by trapping experiments in the ZnO–ZnS heterostructural system for the degradation of an aqueous solution of MB are also explicated. Trapping experiments indicate that h+ and ˙OH are the main active species in the ZnO–ZnS heterostructural catalyst, which do not effectively contribute in a bare ZnO catalytic system. Our work also highlights the stability and recyclability of the core–Shell nanostructure photocatalyst and supports its potential for environmental applications. We thus anticipate that our results show broad potential in the photocatalysis domain for the design of a visible light functional and reusable core–Shell nanostructured photocatalyst.
Ramaswamy Thangavelu Rajendra Kumar - One of the best experts on this subject based on the ideXlab platform.
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effective Shell Wall thickness of vertically aligned zno zns core Shell nanorod arrays on visible photocatalytic and photo sensing properties
Applied Catalysis B-environmental, 2018Co-Authors: Kuglaur Shanmugam Ranjith, Rutely Burgos Castillo, Mika Sillanpaa, Ramaswamy Thangavelu Rajendra KumarAbstract:Abstract Development of hierarchical core-Shell semiconductor heterostructures ensue significant advancement in catalytic functional structures with improvised optical functionalities. Shell Wall controlled vertically aligned ZnO-ZnS core-Shell nanorod (NR) heterostructures were grown on transparent conductive substrates along the c-axis by sulfidation of aligned ZnO nanorod arrays for visible photocatalytic properties. The effects of the sulfidation time on the morphology, crystalline properties, optical property, photocurrent response, and photocatalytic activity of the catalyst arrays were studied under UV and visible light irradiation. The Shell Wall thickness of these heterostructures influenced in great extent the effective photo responsive charge separation and improved carrier mobility. ZnO-ZnS core-Shell heterostructure having the Shell Wall thickness of 20 nm has exhibited more efficient visible photocatalytic behavior due to effective separation of carriers and improved visible absorption. On further increasing the Wall thickness the catalytic efficiency was reduced due to the poor carrier (hole) mobility in the polycrystalline Shell grains which induced the higher recombination rate. Stability and reusability of ZnO-ZnS core-Shell nanostructures reveals that the ZnS acted as a protective layer over the ZnO NR arrays. In appraisal with ZnO NR arrays, the control over the Shell Wall thickness of ZnO-ZnS core-Shell NR array attributed to the excellent visible photocatalytic activity and improvised absorption of light in visible region at ZnO-ZnS interface and effective separation of photogenerated electron-hole pairs at ZnO-ZnS heterojunctions.
N Sharifi - One of the best experts on this subject based on the ideXlab platform.
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Effect of nanoparticles on the micromechanical and surface properties of poly(urea–formaldehyde) composite microcapsules
Composites Part B-engineering, 2020Co-Authors: M. Ghorbanzadeh Ahangari, A Fereidoon, Mohsen Jahanshahi, N SharifiAbstract:Abstract Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea–formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite Shell Wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the Shell Wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the Shell Wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF Shell behaves as a viscoelastic–plastic material.
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effect of nanoparticles on the micromechanical and surface properties of poly urea formaldehyde composite microcapsules
Composites Part B-engineering, 2014Co-Authors: Ghorbanzadeh M Ahangari, A Fereidoon, Mohsen Jahanshahi, N SharifiAbstract:Abstract Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea–formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite Shell Wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the Shell Wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the Shell Wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF Shell behaves as a viscoelastic–plastic material.
Rupinder Singh - One of the best experts on this subject based on the ideXlab platform.
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Experimental and Analytical Analysis of Light Alloy Shell Castings Using Three Dimensional Printing
2014Co-Authors: Rajesh Kumar, Rupinder SinghAbstract:Growth of rapid prototyping (RP) technologies has proven highly significant in efforts to reduce the production time for a number of casting processes. Lot of research has been done in production of sacrificial sand moulds used in investment casting. This paper systematically presents procedure of producing Shell casting using light alloys in ceramic moulds created with three dimensional printing (3DP). The Shells are made using special sand provided by Z-Corporation for production of easy and economical Shell moulds with creation of 3D printers. Selected part was designed using UNIGRAPHICS modeling software. The moulds using the CAD model were produced with ZCorp 510 RPT machine. An experimental and analytical investigation was conducted to establish the influence of parameters like Layer thickness (Lt), Post curing time (Pc), orientation (O) for printing of Shell. Light alloy Shell castings using aluminium, zinc and lead were produced with the developed moulds. The effect of other parameters like the Shell Wall thickness (SWT), weight density (WD) and pouring temperatures (PT) on mechanical characteristics like hardness, dimensional accuracy and international tolerance (IT) grades of castings was also analyzed experimently. The paper concludes feasibility to reduce the Shell Wall thickness from 12 mm to 2 mm with dimensional accuracy. Consistencies with the permissible range of tolerance grades were achieved. Further at optimised SWT 5 mm, 5 mm and 6 mm, production cost has been reduced by 54.28%, 54.28% and 49.12% and production time has been reduced by 46.05%, 46.28% and 43.42% respectively in comparison to 12mm recommended Shell thickness for selected light alloys.
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Effect of Workpiece Volume on Shell Wall Thickness Reduction in Rapid Casting of Aluminum using Three-Dimensional Printing
International Journal of Automotive and Mechanical Engineering, 2012Co-Authors: Rupinder Singh, Rajinder SinghAbstract:The purpose of the present work is to study the effect of workpiece volume on reducing the Shell Wall thickness in rapid Shell casting based upon three-dimensional printing (3DP) technology, and to evaluate the dimensional accuracy and mechanical properties of aluminum (Al) castings obtained as per the ISO standard UNIEN 20286-I (1995). Starting from the identification of component/benchmark, castings of different volumes (corresponding to workpieces of ɸ60 mm, ɸ50 mm and ɸ40 mm) were produced with different Shell Wall thicknesses. Measurements on a coordinate measuring machine (CMM) allowed the calculation of the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings. The research proved that having a Shell Wall thickness with a value less than that recommended (12 mm) is more suitable from a dimensional accuracy and economic point of view (irrespective of the workpiece volume within the given selected range). All the castings produced with different Shell thicknesses are acceptable as per the ISO standard. The results of the study suggest that workpiece volume has an unnoticeable effect on reducing the Shell Wall thickness for the selected range of volumes of casting. Furthermore, the hardness of castings produced is almost same for all Shell Wall thicknesses, from 12 mm to 1 mm. The results are supported by cooling (time-temperature) curves, which show unnoticeable changes in the rate of heat transfer at different Shell Wall thicknesses. Keeping in mind the cost effectiveness of the process, one (1) mm Shell Wall thickness has been recommended for the production of castings. For a 1 mm Shell Wall thickness, the production cost and time are reduced by 67.38% and 44.87% (for ɸ60 mm workpieces), 64.51% and 44.62% (for ɸ50 mm workpieces), and 69.50% and 59.64% (for ɸ40 mm workpieces), respectively.
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Effect of work piece volume on statistically controlled rapid casting solution of aluminum alloys using three dimensional printing
Materials and Manufacturing Processes, 2012Co-Authors: Rupinder Singh, Rajinder SinghAbstract:The purpose of the present investigations is to study the effect of work piece volume on Shell Wall thickness reduction for a statistically controlled rapid casting solution of aluminum alloy using three dimension printing. The results of the study suggest that work piece volume has an unnoticeable effect on Shell Wall thickness reduction (for the selected range of work piece volume). The research proved that a Shell Wall thickness with a value less than the recommended one (12mm) is more suitable from dimensional accuracy and economic points of view. Final castings produced at different Shell Wall thicknesses are acceptable as per IS standard (UNI EN 20286-I (1995). Keeping in mind the cost effectiveness, one (01) mm Shell Wall thickness has been recommended for production of casting.
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Study the effect of moulding sand properties for reducing Shell Wall thickness in zinc casting using three-dimensional printing
International Journal of Rapid Manufacturing, 2011Co-Authors: Rupinder SinghAbstract:This paper aims to study the feasibility of reducing Shell Wall thickness of zinc (Zn) Shell casting using three-dimensional printing. Experimentation started from the design of benchmark, printing of Shells at different thicknesses, followed by supporting the Shells with dry, green and molasses sands. Prototypes of Zn were produced at different Shell thicknesses of moulds cavities. Cooling curves were drawn to explore the cooling rate/solidification rate of molten Zn metal in hybrid Shells of different thicknesses. The dimensional accuracy of castings produced was measured with coordinate measuring machine and some mechanical properties of castings were also tested to observe the effects of sand properties over the prototypes produced, when casted with Shells of different thicknesses from 12 to 1 mm. It has been observed that it is feasible to reduce Shell Wall thickness recommended from 12 to 1 mm. While comparing hardness of the specimens produced, it was observed that the hybrid casted component with green sand shows more hardness in comparison to components casted with dry and molasses sand. Results also indicate that hybrid casted prototype with green sand at 3 mm Shell thickness shows better dimensional accuracy and mechanical properties.
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Comparison of Hybrid Rapid Mouldings for Zinc Alloy Castings
Applied Mechanics and Materials, 2011Co-Authors: Rupinder SinghAbstract:In this work comparison of hybrid rapid moulds (prepared with three dimensional printing Shells supported with dry, green and molasses sand) have been made for techno-economic analysis, for zinc (Zn) alloy Shell casting. The comparison has been made on the basis of mechanical properties and dimensional accuracy. Time-temperature curves have been drawn to understand solidification of molten Zn alloy in hybrid moulds of different thicknesses. The results of study suggest that it is feasible to reduce Shell Wall thickness of hybrid mould cavity from recommended 12mm to 1mm. All castings prepared are consistent with the permissible range of IT grades and are acceptable as per ISO standard UNI EN 20286-1 (1995). Further green sand based hybrid prototypes at 3mm Shell Wall thickness, shows better dimensional accuracy and mechanical properties.
