Metal Mold Research Articles

A code-based method for carbon emission prediction of 3D printing: A case study on the fused deposition modeling (FDM) 3D printing and comparison with conventional approach

This study presents a method for predicting carbon emissions from 3D printing based on the G-code and compares the emissions between FDM and injection molding (IM) processes. Traditional manufacturing methods for (polylactic acid) PLA plastic products involve IM, which require extensive equipment and metal molds to be manufactured first. This process involves repetitive heating and machining, low material utilization, high energy consumption, and high pollution. 3D printing using a gradual accumulation of materials to manufacture parts has transformed traditional manufacturing methods. However, concerns regarding the environmental impact of 3D printing have been raised in previous studies. To achieve sustainability in 3D printing, it is important to make effective adjustments by predicting the carbon emissions before printing. In this study, we propose a method for predicting carbon emissions from 3D printing by integrating processing characteristics with G-code instructions. The deviation of the model was confirmed to be between 3.86% and 5.82% through a case study of FDM 3D printing. The optimal process parameters were determined from carbon emissions predictions, resulting in carbon emissions reductions of up to 43.77%. Carbon emissions were evaluated using both the traditional IM method and FDM 3D printing for manufacturing PLA plastic products. The results showed that the carbon emissions from FDM were significantly lower than those from traditional IM in small batches or customized production. In the traditional IM method, mold manufacturing produces high carbon emissions, accounting for more than 99% of the entire process. The findings of this study offer valuable guidance to manufacturers in selecting appropriate manufacturing methods and formulating production strategies. By predicting carbon emissions in the FDM process and adjusting the parameters based on product quality requirements, significant reductions in carbon emissions can be achieved during the production of small batches or customized PLA plastic products. The carbon emission prediction method proposed in this study presents a more sustainable solution for 3D printing technology, which is crucial for advancing sustainable production and environmental protection in this field.

PENGARUH PENAMBAHAN UNSUR TEMBAGA PADA PENGECORAN TEKAN BLOK SILINDER BEKAS TERHADAP NILAI IMPAK DAN KEAUSAN

The cylinder liner block is part of the cylinder block which functions as a place for the engine working process to take place. Where in this section the suction, compression, work and exhaust processes occur. Cylinder blocks have two types, some can be repaired and cannot be repaired, to utilize cylinder blocks that cannot be repaired by recycling them by casting metal with copper (Cu) with variations in the addition of 5%, 10%, 15% with a casting temperature of 1150⁰C using metal molds using the press technique method. Data collection was carried out by wear testing, impact testing, and microstructure testing. By increasing the percentage of copper (Cu) in the cylinder block casting, the highest wear was obtained with the addition of 15% Cu of 2,87×10-9 m3. The highest impact strength of 15% Cu is 0.12 Joule/mm2.

Depolymerization of vulcanized poly(cyclopentene), poly(norbornene-ran-cyclopentene) and poly(endo-dicyclopentadiene-ran-cyclopentene) rubbers via ring-closing metathesis depolymerization for monomer recycling.

Herein, we report a study on the preparation, properties, and depolymerization of pristine and vulcanized poly(cyclopentene) (poly(CP)), poly(norbornene-ran-cyclopentene) (poly(NB-ran-CP)) and poly(endo-dicyclopentadiene-ran-cyclopentene) (poly (DCP-ran-CP)). First, poly(CP), poly(NB-ran-CP) and poly(DCP-ran-CP) were prepared with high molecular weight control (M w = 200 000-500 000) using dichloro(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(ii). Next, carbon black, zinc oxide and other additives were blended into the pristine polymers using a mixer and twin roll rubber mills at 50 °C, followed by vulcanization in metal molds at 160 °C for 10 min, resulting in molded black rubber specimens. Crosslinking of the vulcanized rubbers was confirmed by solvent swelling test. Ring-closing metathesis depolymerization (RCMD) of the pristine and vulcanized polymers was conducted. Pristine poly(CP) was smoothly degraded into cyclopentene monomers with only 0.001 mol% of [1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(phenylmethylene)(tricyclohexylphosphino)ruthenium (H2IMes)(PCy3)Cl2Ru[double bond, length as m-dash]CHPh (H2IMes = 1,3-dimesityl-4,5-dihydroimidazolylidene) in toluene at 25 °C for 1 h ([poly(CP) unit] = 0.50 M). In the case of the copolymers, degradation of pristine poly(NB-ran-CP) and poly(DCP-ran-CP) via RCMD also delivered a cyclopentene monomer and residual polynorbornene and poly(endo-dicyclopentadiene), respectively, demonstrating the feasibility of cyclopentene recycling from copolymers. Complete depolymerization of vulcanized poly(CP) rubber was also efficiently achieved using 1 mol% of (H2IMes)(PCy3)Cl2Ru[double bond, length as m-dash]CHPh, affording black inorganic precipitate and separable volatile cyclopentene monomer (in toluene at 60 °C for 24 h, [poly(CP)] = 0.50 M). Similarly, vulcanized poly(NB-ran-CP) (or poly(DCP-ran-CP)) rubber was successfully depolymerized under the same conditions, resulting in black inorganic precipitate, polynorbornene (or poly(endo-dicyclopentadiene)) and a cyclopentene monomer. This study provides a new strategy for monomer recycling of rubber wastes made from cyclopentene-based rubber under relatively mild conditions, contributing to a circular economy and resource efficiency.

PLASTIC BLOCK FOR BUILDING CONSTRUCTION MATERIAL

Plastic wrap waste increase from time to time. Efforts are needed to utilize them as they are less demanded for recycling by the private sectors in Bali and Indonesia. This paper describe effort to use combination of waste thin plastic wrap as plastic block for wall construction material. The plastic wrap wastes were cut into 5-10 mm size, then they were melted in a hot waste engine oil at 200°C. The mixture was then poured into a metal mold, slightly cooled down and compressed using a compression machine. The mixtures produced was without and with added rice husk ash as filling material. The size of the plastic block was 20×10×8cm. It was found that the densities of the samples were less than 1gram/cm3, the compressive strength can achieve 25kg/cm2, the Porosities were low, ranges from 0.220-0.290%, the Initial Rate of Suctions (IRS) were very low ranges form 0.0004-0.00075 kg/m2.minute, and the and water absorptions were also low (0.02-0.03) %. In general, the compressive strengths were comparable to low quality bricks commonly produced.

Effects of Finishing on Surface Roughness of Four Different Glass-Ionomer Cements and One Alkasite: In Vitro Investigation over Time Using Aging Simulation.

In 2017, Europe implemented a ban on amalgam restorations for children aged <15 years and for pregnant/breastfeeding women, highlighting the need for alternative filling materials exhibiting less surface roughness and enhanced longevity. This in vitro study aimed to examine the surface roughness variations of five amalgam-replacement materials across three time points and using six finishing methods: (1) no finishing (control), (2) Arkansas burs, (3) diamond burs, (4) tungsten carbide burs, (5) SofLex discs in descending grit size, and (6) coarse SofLex discs combined with silicone polishing. We prepared 960 samples. Each material group, i.e., Cention Forte (CNF), DeltaFil (DLF), Ketac Universal (KTU), IonoStar Molar (ISM), and Equia Forte HT (EQF), comprised 60 samples (n = 10 per finishing method) created using standardized 3D-printed metal molds. Surface roughness (Sa) was measured immediately after finishing, after 30 days of storage in distilled water, and after thermocycling (5000 cycles) using a non-contact profilometer. The results indicate that conventional and hybrid glass-ionomer cements have smoother surfaces than high-viscosity GICs. The DLF and CNF groups exhibited stable outcomes. These findings underscore the importance of selecting appropriate finishing methods based on the restorative material to minimize surface roughness.

Improvements in Injection Moulds Cooling and Manufacturing Efficiency Achieved by Wire Arc Additive Manufacturing Using Conformal Cooling Concept.

The plastic injection moulding industry is a constantly developing industrial field. This industrial process requires the manufacturing of metal moulds using complex heating and cooling systems. The purpose of this research is to optimize both the plastic injection moulding process and the mould manufacturing process itself by combining practices in this industry with current additive manufacturing technologies, specifically Wire Arc Additive Manufacturing (WAAM) technology. A mould punch was manufactured by using both WAAM technology, whose internal cooling system has been designed under the concept of Conformal Cooling, and conventional cooling channel designs and manufacturing techniques in order to carry out a comparative analysis. Theoretical results obtained by CAE methods showed an improvement in heat extraction in the WAAM mould. In addition, the WAAM mould was able to achieve better temperature homogeneity in the final part, minimizing deformations in the final part after extraction. Finally, the WAAM manufacturing process was proven to be more efficient in terms of material consumption than the conventional mould, reducing the buy-to-fly ratio of the part by 5.11.

Impact of Acidic and Alkaline Environments on the Surface Morphology of Biodentine and White Mineral Trioxide Aggregate - An In-vitro Study.

The physical and chemical properties of calcium silicate cement might be affected due to exposure to acidic or alkaline conditions during clinical use. The present study aimed to evaluate the effect of acidic and alkaline environments on the surface morphology of biodentine (BD) and white mineral trioxide aggregate (wMTA). Disc-shaped specimens of BD (n = 30) and wMTA (n = 30) were prepared in a metal mould and wrapped in pieces of gauze. They were divided into three sub-groups according to the storage media: group A, soaked in sterile distilled water at a pH of 7.0; group B, exposed to butyric acid buffered at pH 4.0; and group C, exposed to calcium hydroxide solution buffered at pH 12.0. The specimens were incubated for 7 days at 37°C, followed by examination under scanning electron microscopy at 1000x and 5000x magnification to characterise the microstructural morphology. Definite changes were seen in the microstructure of BD and wMTA on exposure to acidic and alkaline pH. The microstructure of wMTA tends to exhibit reduced cohesion when exposed to an acidic environment, especially when compared to an alkaline pH. Acidic pH exerts a milder influence on the morphological structure of BD when contrasted with its effects on wMTA. Biodentine may emerge as a more prudent choice than wMTA for utilisation in inflamed periapical regions.

A 3D-Printed, High-Fidelity Pelvis Training Model: Cookbook Instructions and First Experience.

Background: Since laparoscopic surgery became the gold standard for colorectal procedures, specific skills are required to achieve good outcomes. The best way to acquire basic and advanced skills and reach the learning curve plateau is by using dedicated simulators: box-trainers, video-trainers and virtual reality simulators. Laparoscopic skills training outside the operating room is cost-beneficial, faster and safer, and does not harm the patient. When compared to box-trainers, virtual reality simulators and cadaver models have no additional benefits. Several laparoscopic trainers available on the market as well as homemade box and video-trainers, most of them using plastic boxes and standard webcams, were described in the literature. The majority of them involve training on a flat surface without any anatomical environment. In addition to their demonstrated benefits, box-trainers which add anatomic details can improve the training quality and skills development of surgeons. Methods: We created a 3D-printed anatomic pelvi-trainer which offers a real-size narrow pelvic space environment for training. The model was created starting with a CT-scan performed on a female pelvis from the Anatomy Museum (Cluj-Napoca University of Medicine and Pharmacy, Romania), using Invesalius 3 software (Centro de Tecnologia da informação Renato Archer CTI, InVesalius open-source software, Campinas, Brazil) for segmentation, Fusion 360 with Netfabb software (Autodesk software company, Fusion 360 with Netfabb, San Francisco, CA, USA) for 3D modeling and a FDM technology 3D printer (Stratasys 3D printing company, Fortus 380mc 3D printer, Minneapolis, MN, USA). In addition, a metal mold for casting silicone valves was made for camera and endoscopic instruments ports. The trainer was tested and compared using a laparoscopic camera, a standard full HD webcam and "V-Box" (INTECH-Innovative Training Technologies, Milano, Italia), a dedicated hard paper box. The pelvi-trainer was tested by 33 surgeons with different qualifications and expertise. Results: We made a complete box-trainer with a versatile 3D-printed pelvi-trainer inside, designed for a wide range of basic and advanced laparoscopic skills training in the narrow pelvic space. We assessed the feedback of 33 surgeons regarding their experience using the anatomic 3D-printed pelvi-trainer for laparoscopic surgery training in the narrow pelvic space. Each surgeon tested the pelvi-trainer in three different setups: using a laparoscopic camera, using a webcam connected to a laptop and a "V-BOX" hard paper box. In the experiments that were performed, each participant completed a questionnaire regarding his/her experience using the pelvi-trainer. The results were positive, validating the device as a valid tool for training. Conclusions: We validated the anatomic pelvi-trainer designed by our team as a valuable alternative for basic and advanced laparoscopic surgery training outside the operating room for pelvic organs procedures, proving that it supports a much faster learning curve for colorectal procedures without harming the patients.

Characterization of Some Local Clay Minerals and Fabrication into Ceramic Floor-Tiles

Clay minerals deposits, which include, kaolin, ball-clay, fireclay and zircon, were investigated and used in fabrication of ceramic floor tiles. X-ray diffractometer (XRD-6100, Japan), was used to examine the various compositions and structures of the clay samples. 2000 grams of 0.005 mm grain size of each sample were homogeneously mixed into dough, compressed in metallic mould of 12 mm × 36 mm dimension, and allowed to dry for about 5 hours. Kiln draught oven, at 1200°C was set for glazing and firing of the moulded tiles, to ensure glossy appearance, smoothness and improved strength. XRD test showed higher content of alumina (Al&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;) and Silicon (iv) oxide (SiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;) in all the clay samples. The percentage composition of Critobalite, Diphosphorus trioxide (P&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;), Potassium Oxide (K&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O) and Sodium Oxide (Na&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O), were reasons for their excellent workability, improved mechanical and rheological properties of ceramics floor-tiles. Water absorption, chemical resistance, shrinkage properties of the different ceramic tiles were compare to some commercial products. This investigation had shown that locally available clay minerals could be fully integrated into ceramic industries to reduce cost of ceramic importation and create job opportunities for youths.

Corrosion Resistance of Reinforcement in Reinforced Concrete Products

The compositions of modified concrete and grease for metal molds have been developed, which can be recommended for wide implementation in production to increase the corrosion resistance of reinforcement. Therefore, the purpose of the study is to protect the reinforcement from corrosion in the specified period (corrosion of reinforcement begins after 15 min) is an important problem in increasing the durability of reinforced concrete products. Methods of research of reinforced concrete products show that for several technological reasons prepared for molding products form with installed and – fixed reinforcement is in the unfilled concrete state from 30 to 60 minutes and more. Steel reinforcement in the concrete, during the manufacture of which the molds were lubricated with the lubricant developed by us, is in an even more favorable (passive) state. Even after 10 min of measurements, the potential of steel, also polarized to +600 mV, did not reach its stationary value and was at the level of +90 mV values.

Optimizing hot tearing susceptibility of Al-5.5Zn-2.4 Mg-1.3Cu alloys by grain refinement, increasing mold and casting temperature

The Al-Zn-Mg-Cu alloy is widely used in automotive lightweighting and other applications due to its excellent mechanical properties. However, when this alloy is cast using metal molds, it exhibits high hot tearing susceptibility (HTS), increasing the risk of use. Volumetric shrinkage due to density differences during the transition from liquid to solid metal produces shrinkage stresses. At the same time, lacks feeding of the remaining liquid phase in the late solidification stage can also lead to hot tearing. The purpose of this paper is to present a device for quantitatively determining and optimizing HTS. The relationship between solidification shrinkage displacement and stress was tested in a quantitative way using a Self-designed T-tester equipped with stress and displacement sensors. The test results show that the reduction of grain size shifts the solidification shrinkage of the alloy and reduces the solidification shrinkage stress, which avoids hot tearing caused by higher solidification shrinkage stress and local stress inhomogeneity. Secondly, the grain size reduction increases the number of feeding channels in the solidification vulnerable stage, and more liquid phase is available for crack healing. In addition, the influence of casting process parameters on the HTS was studied.

Microstructure phase analysis and process optimization of ZL205A metal mold casting

In this paper, we take an elastomeric transmission structure part made of ZL205A alloy as the research object, and use the metal type gravity casting technology for casting trial production, analyze the quality and mechanical properties of the molded parts of ZL205A alloy parts under different process parameters, optimize the casting process parameters, get the optimal combination of process parameters, and obtain large ZL205A castings with less internal quality defects and high mechanical properties.

Comparative evaluation of vat photopolymerization and steel tool molds on the performance of injection molded and overmolded tensile specimens

AbstractThis study explores the use of vat polymerization stereolithography (SLA) for fabricating mold tooling, subsequently utilized in injection molding (IM) and overmolding of tensile specimens and directly compared to those produced using metal molds. The results first find the manufacturing time for an SLA‐fabricated mold is remarkably short, approximately 6 h, presenting a substantial improvement over traditional methods. Mechanical testing revealed that the tensile specimens from the SLA‐fabricated molds exhibited the highest tensile strength among all overmolding batches. This performance was consistent with the tensile bars produced using metal molds, demonstrating the viability of SLA‐fabricated molds for overmolding applications and highlighting the potential of FDM to customize the properties of final products. However, variations in mold types impacted the dimensional tolerance and tensile strength of the final specimens. Metal mold‐fabricated tensile bars exhibited superior dimensional accuracy and maximum tensile strength (50.6–61.7 MPa) compared to those produced with SLA‐fabricated molds (46.9–55.9 MPa). These differences are attributed to the rougher surface finish inherent to the layer‐by‐layer construction of SLA and the internal stresses and defects resulting from lower thermal conductivity and uneven cooling. In conclusion, this study underscores the promising future applications of SLA‐fabricated molds in overmolding, offering reduced manufacturing costs and enhanced design freedom. The findings support the potential of SLA to revolutionize mold fabrication, thereby extending its utility and optimizing the production of polymer components with customized properties.Highlights SLA molds compared to metal molds for direct injection molding and overmolding. FFF preforms with varied geometries were overmolded to finalize the specimens. Joint configurations in overmolding improved tensile performance. Overmolding showed better dimensional accuracy than FFF specimens. SLA mold preparation significantly reduced manufacturing costs.

Evaluation of Tensile Bond Strength of Nanoparticle Reinforced Soft Liner Materials: A Pilot Study

OBJECTIVE: The aim of this study is to evaluate the tensile bond strength between polymethyl methacrylate (PMMA) surfaces and autopolymerized silicon-based soft lining materials with 1% w/w Titanium dioxide (TiO2) and Hydroxyapatite (HA) nanoparticles added. MATERIALS AND METHODS: For the tensile test, 60 pieces of acrylic (Meliodent, Bayer Dental, Newbury, England) samples of 30 × 10 × 10 mm3 dimensions were prepared using metal molds. Acrylic surfaces were sanded with silicon carbide sandpapers of 500, 1000, 1500, and 2000 grids to ensure standardization. After the samples were placed back in the metal mold, adhesive (Detax, Germany) was applied to the surfaces that would come into contact with the soft lining. Soft lining materials (Mollosil, Detax, Ettlingen, Germany) to which 1% by weight TiO2 and 1% HA nanoparticles were added were polymerized by placing them between two acrylic blocks. For the tensile test, a total of 30 samples were obtained, with 10 samples in each group (n=10). The specimens were placed on the holder end of the universal test device and force was applied until failure occurred. RESULTS: The tensile bond strength (0,86 ± 0,21 MPa) in the TiO2 nanoparticle-added group was found to be significantly higher than the control group (0,65 ± 0,14 MPa) (p&amp;lt;0.05). There is no significant difference between the control group and the HA nanoparticle-added group (0.65 ± 0.1 MPa) (p˃0.05). CONCLUSION: It was observed that the addition of nanoparticles increased the tensile strength. However, further studies are needed to evaluate the effect of nanoparticle addition on other mechanical and physical properties of soft liners.

In Vitro Kinetic and Thermodynamic Staining Study of Three Energy Drinks on the Restorative Charisma Composite

Abstract Aim: The research utilized charisma composite resin, a dental restorative material known for its esthetic properties, with the chemical formula 2,2-bis[p(2-hydroxy-3-methacryloxy propoxyphenyl)] propane. The primary objective of the study was to examine the overall color change (ΔE*ab) of the charisma resin after it was subjected to three distinct energy drink solutions: Monster Energy Ultra-Sunrise, Wild Tiger, and Red Bull. Further we examined the effects of temperature and time on the staining interaction and overall color difference ΔE*ab on the surface of charisma restorative resin generated by three energy drink. Materials and Methods: A microfilled Charisma Classic composite resin was used in presented comparative study selected. The prepared 144 composite disk samples (subdivided n=48) with random allocation method were used for the three energy drinks to determine the effect of temperature and time over the course of 90 days. A metallic circulator mold was prepared. Every set of 48 specimens in the energy drink was heated in a water bath for 1, 7, 30, 60, and 90 days at four different temperatures This investigation spanned various time intervals, ranging from 1 to 90 days, and encompassed four temperature levels between 283 and 310 K. One-way ANOVA was used to evaluate the mean data for color change between the energy drinks, and Tukey’s post hoc test was used for multiple comparisons, with a significance level of P &lt; 0.05. Results: The study revealed that the rate of staining was most pronounced in the case of Wild Tiger, while it was comparatively lower for Monster Energy Ultra-Sunrise. These findings were established through an examination of the kinetic and thermodynamic behavior of surface color changes in micro-hybrid composites treated with the three energy drink solutions. Conclusions: The observed patterns aligned with the pseudo second-order model. It was observed that the Red Bull drink displayed a negative activation energy, resulting in a slower color change rate with increase in temperature. In contrast, endothermic, spontaneous, and regular staining activity was demonstrated throughout time by Monster Energy Ultra-Sunrise and Wild Tiger.

Enhancing the antibacterial and surface hardness of glass ionomer cement modified with Salvadora persica and Chlorhexidine: An in vitro study.

This laboratory study evaluated the effect of Salvadora persica (S. persica) root extracts and Chlorhexidine Digluconate (CHX) on the antibacterial and surface hardness properties of glass ionomer cement (GIC). The in vitro experimental study was conducted at the Baqai Institute of Pharmaceutical Sciences of Baqai Medical University, Karachi, Pakistan, from October 2022 to March 2023. There were a total four experimental groups. The first group consisted of ethanol extract (GIC-SPEE) and second group consisted of hexane extract as (GIC-SPHE) both prepared from Salvadora persica root respectively, and mixed with liquid of GIC separately. The third group comprised chlorhexidine (GIC-CHX) that was also mixing into liquid portion of GIC and the last group was Control i.e. (cGIC). The GIC samples were prepared by using stainless steel metallic moulds with dimension (5mm x 2mm), following the manufacturer guidelines. Antibacterial activity against Streptococcus mutans was done by disc diffusion test (DDT), and surface hardness test was done by Vickers hardness tester. Statistical analysis was performed using One-Way ANOVA and Tukey's post hoc tests (p<0.05). The antibacterial activity against S. mutans reported that the maximum zone of inhibition was obtained at 3 wt% by the GIC-SPEE, when compared with other experimental groups. For surface hardness, the highest mean and standard deviation and significant findings was reported by the group GIC-SPEE. Considering the outcome of this in vitro study, it can be concluded that the addition of 3 wt% GIC-SPEE increased the surface hardness and antibacterial activity against Streptococcus mutans.

Microwall array tactile sensor fabricated by transferring CNT/PDMS composite material into high aspect metal mold

This paper proposes a slip sensor that assists an industrial robot to grasp an object with the minimum force required. The sensor developed in this study can detect whether an object is being pressed or sliding inside the robot hand. The developed sensor was fabricated using a custom-made metal mold, which is a block of 20 mm square and 3 mm thick with lines and spaces of 0.4 mm pitch and 2 mm depth, forming a vertical wall array (50 in total) with finely high aspect ratio of 10, i.e., the height of each wall is 2 mm and the thickness is 0.2 mm. The flexible sensor body is obtained by pouring a composite of polydimethylsiloxane (PDMS) and carbon nanotubes (CNTs) into this mold, heating it to solidify it, and then releasing it from the mold. This sensor is intended to attach to the grasping surface of a robot hand. This sensor is a resistive one, i.e., changes in the sensor's internal circuitry when the robot hand grasps an object are expressed as changes in the sensor resistance. The sensor can both estimate the pressing force and detect the object slippage, since the resistance rapidly changes when a slippage occurs. This sensor allows the robot to detect the contact state with a handling object.

Correlation between Dental Composite Filler Percentage and Strength, Modulus, Shrinkage Stress, Translucency, Depth of Cure and Radiopacity.

Filler content in dental composites is credited for affecting its physical and mechanical properties. This study evaluated the correlation between the filler percentage and strength, modulus, shrinkage stress, depth of cure, translucency and radiopacity of commercially available high- and low-viscosity dental composites. Filler weight percentage (wt%) was determined through the burned ash technique (800 °C for 15 min). Three-point bend flexural strength and modulus were measured according to ISO 4049 with 2 mm × 2 mm × 25 mm bars. Shrinkage stress was evaluated using a universal testing machine in which composite was polymerized through two transparent acrylic rods 2 mm apart. Shrinkage was measured from the maximum force following 500 s. The translucency parameter (TP) was measured as the difference in color (ΔE00) of 1 mm thick specimens against white and black tiles. The depth of cure was measured according to ISO 4049 in a cylindrical metal mold (4 mm diameter) with a 10 s cure. Radiopacity was measured by taking a digital X-ray (70 kVp for 0.32 s at 400 mm distance) of 1 mm thick specimens and comparing the radiopacity to an aluminum step wedge using image analysis software. The correlation between the filler wt% and properties was measured by Pearson's correlation coefficient using SPSS. There was a positive linear correlation between the filler wt% and modulus (r = 0.78, p < 0.01), flexural strength (r = 0.46, p < 0.01) and radiopacity (r = 0.36, p < 0.01) and negative correlation with translucency (r = -0.29, p < 0.01). Filler wt% best predicts the modulus and strength and, to a lesser extent, the radiopacity and translucency. All but two of the high- and low-viscosity composites from the same manufacturer had statistically equivalent strengths as each other; however, the high-viscosity materials almost always had a statistically higher modulus. For two of the flowable composites measured from the same manufacturer (3M and Dentsply), there was a lower shrinkage stress in the bulk-fill version of the material but not for the other two manufacturers (Ivoclar and Tokuyama). All flowable bulk-fill composites achieved a deeper depth of cure than the flowable composite from the same manufacturer other than Omnichroma Flow Bulk.

The Impact of Copper on the Mechanical Properties of Cast Motorcycle Cylinder Blocks

Enhancing the mechanical properties of cast products can be achieved by adding other elements. This research investigates the effect of copper (Cu) on the mechanical properties of cast motorcycle cylinder blocks, verified through microstructure analysis. Experiments were conducted by adding varying amounts of copper (Cu) at 5%, 10%, and 15%, with a casting temperature of 1010°C using a metal mold. Data collection included hardness testing, tensile strength testing, and microstructure analysis.The results showed that increasing the percentage of copper (Cu) in the cylinder block casting led to significant improvements in mechanical properties. The highest Vickers hardness was achieved with the addition of 15% Cu, measuring 229.23 HV. Similarly, the highest tensile strength was observed with the 15% Cu addition, reaching 104.218 MPa. Microstructure analysis revealed that the casting results predominantly consisted of α Al+θ (CuAl₂)+βSi phases, which were smaller compared to the α Al phase.

Ageing Characteristics of Stir Cast AZ 61 Alloy with Minor Additions

Background: Knowing that magnesium (Mg) alloys and its composites bear the potential of being used simultaneously for light structural as well as biomedical applications, it appears prudent to look for developing a novel Mg alloy; the concurrent demand is to monitor recent trend in development of functional Mg-alloy and its composite materials through extensive patent search. Review of recent patents in the related field makes it relevant to investigate this aspect. Objective: The authors aim to study the evolution of structure and properties in stir cast of AZ- 61 alloy with minor additions of scandium, calcium and manganese. This paper reports the results of this investigation. Methods: The castings are prepared by stirring the molten alloy at 600 rpm for 10 minutes, followed by pouring into a preheated metal mould. The solidified alloys are homogenized at 550°C for 12 hours. The homogenized alloys are then subjected to solutionising treatment at 500°C for 5 hours; subsequently, the alloys are quenched in iced water. The quenched alloys are subjected to ageing treatment at different temperatures between 100°C to 400°C at an interval of 100°C. Similar experiments are conducted with its statically cast counterparts. The structure and properties of all the samples have been characterized by optical and scanning electron microscopy, and XRD analysis; DSC heating run is conducted to study the kinetics of phase transformation. Mechanical behaviour of castings is studied with the aid of tensile testing and fractography. Moreover, tribological behaviour of alloys is assessed by wear testing with the help of pin on disc method. Results: The results show that the stir cast alloy produces a homogeneous structure with significant improvement in properties. The precipitates of Mg17Al12, Al Mn, Mg Zn2, Al2 Ca and Mg2 Ca are formed due to the ageing of both stir cast and statically cast alloy. It is found that the diffusion of Al in magnesium controls the precipitation process. The tribological properties are found to be satisfactory for the stir cast alloy. Conclusion: The modified AZ61 alloy with minor additives, achieves excellent structural homogeneity and mechanical properties after stir casting followed by quench ageing.