Properties Of Mold Research Articles

History of lead in dentistry

Lead, renowned for its malleability, enjoyed widespread popularity in dentistry due to its facile moulding properties. Throughout ancient times until the 18th and 19th centuries, lead found applications in dentistry for restorations and pulp capping. However, over the last 100-150 years, this once-prevalent dental filling material fell out of favour due to its propensity for discolouration and adverse health effects.

Impact of the Different Moulding Parameters on Properties of the Green Sand Mould

Impact of the Different Moulding Parameters on Properties of the Green Sand Mould

Study on interlayer bonding properties of multi-material composite cast mold

Multi-material composite cast mold has excellent casting performance, which can produce high quality castings. The interfacial bonding properties of multi-material composite sand mold were studied and the results showed that the overall strength of the composite sand was increased gradually, the bonding bridge area became larger and thicker, and the air permeability was improved with the increased proportion of silica sand mass in the “middle layer” sand. The casting properties were improved, the casting microstructure was refined, the casting cost was reduced, and the amount of adhesive was reduced compared with the silica sand casting.

Comparative characteristics of products of processing of fusible copoly (urethane-imides) from the solutions and melts formed by them

Self-supporting films and thick-walled moldings (blades) were obtained from solutions and melts of multiblock (segmental) copoly(urethane-imides). The initial copoly(urethane-imides) were obtained on the basis of aliphatic polyesters: poly(propyleneglycol), poly(diethyleneglycoladipinate) and polycaprolactone, dianhydride of 1,3-bis(3’,4-dicarboxyphenoxy) benzene and aromatic diamines: 4,4’-bis-(4”-aminophenoxy)biphenyl and 1,4-bis(4’-aminophenoxy)diphenylsulfone. Samples of films and moldings were studied by IR spectroscopy, TGA, DSC and mechanical analysis under static and dynamic (DMA) experimental conditions. It is assumed that the diff erences in the properties of films and moldings are due to an increase in the proportion of aromatic blocks due to microdestruction of polymer chains and increased interfacial interactions of polyester and urethanimide microphases (blocks) in polymer systems during the processing of polymers from the melt by injection molding.

Starch consolidation of calcium carbonate as a tool to develop lightweight fillers for LDPE-based plastics

Calcium carbonate (CaCO3) is used as a filler to improve the stiffness and processability of plastics at low cost. However, its high density limits the quantity to be used. In this work, the feasibility of using starch consolidation of eggshells-derived CaCO3 (ES) to develop lightweight fillers for low density polyethylene (LDPE)-based materials was studied. Starch, recovered from potato by-products, was combined with ES, gelatinized, dried, and milled as a fine powder. The obtained ES/starch-based particles were then compounded with LDPE and their influence on chromatic, mechanical, morphological, and density properties of mold injected LDPE-based materials was studied. Commercially available CaCO3 (COM) was used as control. ES/starch particles were 18 times less dense than the commercially available CaCO3 (2.62 g cm−3). When incorporated into LDPE-based formulations, ES/starch originated brownish materials with lower density (1.18 g cm−3) and higher stiffness (542 MPa of Young's modulus) than those produced with the COM sample (1.33 g cm−3 of density; 221 MPa of Young's modulus). Therefore, starch consolidation of ES revealed to be a promising approach to develop lightweight fillers able to provide stiffness and color to LDPE-based plastics, while valorizing biomolecules-rich by-products.

Biosynthesis of Silver Nanoparticles on Biomedical Moulding Sand Properties for Casting Applications

Present work explains green nanotechnology technique in solid waste management. Solid wastes are generated from domestic, industrial, agricultural, commercial, health care and individual activities etc. Because of rising population, urbanisation, construction activities, and improper medical waste management, there is an increase in biomedical waste, which contributes to widespread landscape littering. Due to its inability to biodegrade, waste disposal has consequently become a significant issue on a global scale. Research is being carried out to develop ways for environment friendly disposal of biomedical wastes. Also, to enhance the moulding properties for better casting quality by using nanoparticles prepared in laboratory by green nanotechnology technique. The main objective of the work is preparation and characteristic study of modified biomedical waste used in green sand moulding for casting industry. The sand silica in green sand moulding material is replaced by biomedical waste. Nanoparticles are synthesized by green nano technology technique used as an additive in bio medical waste which will be treated as modified bio medical waste. Present study evaluated the influence of nano particles on biomedical waste which helps in metal moulding applications.

Post-Molding Shrinkage, Structure and Properties of Cellular Injection-Molded Polypropylene.

Cellular injection molding is a common method of modifying polymer materials aimed at reducing the sink marks on moldings’ surfaces while reducing their weight. However, the dimensions of polypropylene (PP) samples as well as their mechanical properties after the injection molding process change as a result of re-crystallization. Knowledge of dimensional accuracy and awareness of the change in mechanical properties of products during conditioning are very important aspects in the polymer processing industry. The aim of this study was to assess the changes in the value of processing shrinkage and the size of the sink marks of porous PP moldings depending on the degree of porosity and the time since they were removed from the injection mold cavity. Studies of the structure and mechanical properties of moldings were carried out after several conditioning time intervals. The maximum conditioning time of samples was 840 h at 23 °C. Based on the analysis of the test results, it was found that the cellular injection molding process with the holding phase reduces the nucleation of gas pores, which results in a smaller reduction of sink marks than in the case of samples produced without the holding phase. However, PP moldings with a porosity degree equal to 8.9% were characterized by a higher shrinkage value after 1 h of conditioning, compared to moldings with porosity equal to 3.6%. The extension of the conditioning time also resulted in an increase in the value of linear shrinkage and the properties determined during tensile tests of solid and porous samples. Furthermore, in the case of samples with the highest porosity, the impact strength was reduced by about 30% after 840 h of conditioning compared to results obtained after 1 h.

Determination of flow distance of the fluid metal due to fluidity in ductile iron casting by artificial neural networks approach

Abstract Ductile irons (DIs) have properties such as high strength, ductility, and toughness, as well as a low degree of melting, good fluidity, and good machining. Having these characteristics make them the most preferred among cast irons. The combination of excellent properties, especially in DI castings with a thin section, make it an alternative for steel casting and forging. But in the manufacture of thin-section parts, fluidity characteristics need to be improved and the liquid metal must fill the mold completely. The fluidity of liquid metal is influenced by many factors depending on the casting processes such as material and mold properties, casting temperature, inoculation, globalization, and grain refinement. In this study, an artificial neural network (ANN) model has been developed that allows for determining the flow distance of the liquid metal in the sand mold casting method under changing casting conditions of DI. Thus, the flow distance was estimated depending on the cross-sectional thickness during the sand casting under changing casting conditions. The experimental parameters were determined as casting temperature, liquid metal metallurgy quality, cross-sectional thickness, and filling time. Filling modeling was performed with FlowCast software. When the results were examined, it was seen that the developed ANN model has high success in predicting the flow distances of the liquid metal under different casting conditions. The calculated coefficient of determination (R 2) value of 0.986 confirms the high prediction performance of the model.

A holistic evaluation of the influence of shear rates and matrix viscosity on the properties of polypropylene/multi‐walled carbon nanotubes composites

AbstractIn this work, a comparative study on the electrical, morphological, and thermal properties of polypropylene/multiwalled carbon nanotubes (PP/CNT) composites which were prepared by three different processing methods, such as compression molding (CM, shear rate: ~0 s−1), conventional injection molding (CIM, shear rate: ~102 s−1), and microinjection molding (μIM, shear rate: ~105 s−1), was reported. The difference in shear rates among these processing methods and matrix viscosity would significantly affect the state of filler distribution, thereby determining the properties of subsequent moldings. Electrical conductivity results showed that the percolation threshold of PP/CNT moldings followed a trend of μIM > CIM > CM. A higher degree of CNT orientation and a better filler distribution were achieved under the influence of higher shearing conditions, as corroborated by scanning electron microscope observations and Raman spectral analysis. Moreover, increasing filler concentrations played a positive role in improving the thermal stability of PP/CNT composites and the formation of CNT network was believed to be a contributing factor.

PREVENTING FLASH OCCURRENCE IN THE INJECTION PLASTIC MOULD

This article deals with the injection moulding into the plastic mould. This is an unconventional approach to injection moulding, especially because the 3D printing is used to produce the mould. The mould with the same shape was made of a conventional material (aluminium) for comparison. The properties of the plastic mould were then compared to the aluminium mould. The flash was seen as the main shortcoming. The modifications of the mould were suggested in two variants, one of them was implemented. The advantage of the flash solution was described. Finally, other solution options were summarized based on the performed testing.

Investigation on Different Compositions of Clay and Water to the Permeability of the Silica Sand Used in Greensand Casting Mould

Greensand casting is a casting process that uses mixture of silica sand with addition of control additions which are bentonite clay and the presence of water. Control additions influence the mechanical properties of greensand casting mould, for this study focuses on the permeability. Bentonite clay acts as a binder and activated by water to develop strength and plasticity thus the greensand casting mould can be formed. Permeability is ability of gas to pass through the moulding mixture aggregates in order to reduce the defects due to trapped gasses in mould cavity such as blow holes or pin holes. The objective of this study is to investigate the effect of control addition (water and clay) on the permeability number of silica sand sample (tailing sand) from former tin mine site in Tronoh, Perak. Experiments are conducted according to American Foundrymen Society (AFS) standard of procedures. Sand sample is sieved using mechanical sieve shaker to size of 425 µm. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various mixtures of sand-clay–water ratios are compacted by applying three ramming blows of 6666 grams using Ridsdale-Dietert metric standard rammer. The test pieces are tested for permeability with Ridsdale-Dietert permeability meter. The results show that clay and water have affected the permeability of silica sand sample and when more water and clay added, into the moulding mixture, the permeability is found decreased. The appropriate allowable water and clay content are crucial for permeability number of greensand casting mould.

Selected Physical and Spectroscopic Properties of TPS Moldings Enriched with Durum Wheat Bran.

The impact of the amount of durum wheat bran additive used on the selected structural, mechanical, and spectroscopic properties of thermoplastic starch moldings was examined in this study. Bran was added to corn starch from 10 to 60% by weight in the blends. Four temperature settings were used for the high-pressure injection: 120, 140, 160, and 180 °C. The highest value of elongation at break (8.53%) was observed for moldings containing 60% bran. Moreover, for these moldings, the tensile strength and flexural strength were lower (appropriately 3.43 MPa and 27.14 MPa). The highest deformation at break (1.56%) were obtained for samples with 60% bran and injection molded at 180 °C. We saw that higher bran content (50 and 60%) and a higher injection molding temperature (160 °C and 180 °C) significantly changed the color of the samples. The most significant changes in the FTIR spectra were observed at 3292 and 1644 cm−1 and in the region of 1460–1240 cm−1. Moreover, notable changes were observed in the intensity ratio of bands at 1015 and 955 cm−1. The changes observed correspond well with the amount of additive used and with the injection temperature applied; thus it may be considered as a marker of interactions affecting plasticization of the material obtained.

Patterning High-Resolution Microstructures on Thermoplastics by Ceramic Nanoparticles Filled Epoxy Coated Molds for Duplicating Nature-Derived Functional Surfaces.

Patterning high-resolution microstructures on thermoplastic substrates is of fundamental importance for the commercialization of microfluidics, advanced functional surfaces, and optical elements. Though many methods are developed to fabricate micropatterned plastic devices with 100 μm resolution, they suffer substantially higher cost or lower productivity when the resolution of the micropatterns is to be further improved. Here, we develop low-cost molds consisting of thin ceramic-filled-epoxy composite coatings on steel substrates. By virtue of the loaded ZrO2 nanoparticle fillers, the enhanced mechanical and thermal properties of the composite molds enable the epoxy microstructures to survive harsh conditions in conventional thermoplastic processing methods including hot embossing, imprinting, and mold injection. With the ceramic-filled-epoxy coated molds, we are able to improve the fabrication resolution of microstructures on plastics to 10 μm with unprecedented low-cost and excellent durability.

Experimental Investigation of the Influence of Sand and Binder Composition on the Mold Properties of Alkyd Type No-Bake Chemically Bonded Sand-Casting System

In comparison to green sand moulds, chemically bonded resin sand moulds have better dimensional accuracy, surface quality, and sand mould qualities. To survive sand drops when pouring molten metal, the mould cavity formed using a chemically bonded sand mould technique must have appropriate permeability, strength, and hardness. The desire for better permeability, strength, and mould hardness is based on a thorough investigation and analysis of the affecting parameters, such as resin percentage, hardener, and catalyst. The influence of binder content on the moulding qualities of silica sand bound with Alkyd oil urethane binder was investigated. Using a sieve shaker, the experimental materials were sieved and manually blended with the binders. AFS standard test specimens (50 mm diameter by 50 mm height) were prepared using a sand rammer, and four key moulding parameters were determined using a universal sand strength machine, permeability meter, and mould hardness tester: green compression strength (GCS), green shear strength (GSS), permeability, and mould hardness. For the minimal experiments, Box-Behnken experimental matrices were used, and the statistical significance of influencing factors and their interactions will be identified to manage the process. To statistically validate the model, an analysis of variance (ANOVA) test was performed using Minitab. Mold hardness, strength, and permeability will each have their own mathematical equation, which was stated as a nonlinear function of input factors based on experimental input-output data. To optimize the process parameters, a response optimizer (using Minitab) has been used. The results revealed that increasing the resin concentration from 1% to 2% enhances permeability and GSS while decreasing GCS and mould hardness. Hardener was increased from 18 to 20%, which resulted in a drop in permeability and GSS but an increase in GCS and mould hardness. Similarly, increasing the catalyst concentration from 2% to 10% reduces permeability and mould hardness while increasing GCS and GSS.

The Impact of Selected Laser-Marking Parameters and Surface Conditions on White Polypropylene Moldings

Laser marking of polymer materials is a technology that is increasingly used in industry. Polypropylene (PP) shows a low ability to absorb electromagnetic radiation in the near-infrared range (λ = 1064 nm). The paper presents the influence of the surface condition of white-colored polypropylene moldings on the efficiency of their marking with a laser beam. In addition, the operation of the commercial laser marking additive (LMA) Lifolas M 117009 UN, intended to support the process of laser marking of polyolefin surfaces, was verified. The study is an attempt to combine laser operating parameters, material, and geometric properties of PP moldings to obtain the expected quality of graphic symbols. The test samples were made by injection molding method with the use of a specially designed modular injection mold. The molding cavities were prepared with various methods of metal processing, thanks to which obtained moldings differed in surface condition. The marking effects were assessed based on colorimetric tests and digital image analysis. The 0.5 wt% LMA content resulted in obtaining a graphic sign with high contrast in comparison to the background. The gradual increase in the modifier content resulted in a further increase in contrast. These values depended on the degree of surface finish of the samples, and therefore on the roughness parameters. Samples with a rough surface finish showed higher contrast compared to surfaces with a high surface finish. It was also found that for the analyzed moldings, the laser-marking process should be performed with the use of a low head velocity (450–750 mm/s) and a high concentration of the laser beam (0.03–0.05 mm).

Study of the effect of modification on the performance properties of cast iron molds. Part 2

Reducing consumption and increasing the durability of the molds is a reserve in decreasing the costs of steel production, more attention should be paid to the quality of production and operation of the molds. The research focuses on the specifics of modifying gray cast iron for the production of steel molds. Difficult mode of exploitation imposes strict requirements both on the design of the molds and on the materials from which they are made. They must reliably withstand the effects of steel cast in them having a temperature of 1600 °C, thermal shock, directly proportional to this temperature, as well as significant in magnitude cyclic thermal stresses and strains. Specific work conditions of the molds (high heating temperature, their installation on mobile and stationary ditches, intensive cargo flows, etc.) make it difficult to conduct the necessary research directly in the process of their operation. Investigations were carried out on physical models of molds for expendable electrodes of vacuum-arc melting, with a scale of geometric similarity 1:10. Subjected to tests were cast iron models of molds modified with ferrosilicon(FS65), primary aluminum A99, vanadium slag (ShVD-1), ferrosilico-barium (FSB30) and silicomishmetal (SIMISH-1) Fe-30%, La-12%, Ce-30%, Si-28%). These modifiers were chosen for modification because they have wide application in production. The composition of cast iron was adjusted by adding appropriate ferroalloys and by mixing cast and remelted cast iron.

Multi-objective optimization of alloying elements to enhance the wear resistance and impact strength of HCCI produced by furan sand mold

High Chromium White Cast Iron (HCWCI) plays a major role in manufacturing of wear-resistant components. Due to unique wear resistance property, attribution to the additions of carbide forming elements, they have been used for mill liner applications. By varying the wt% of alloying elements such as Cr, Ti, and Mo, the wear resistance and impact strength of High Chromium Cast Iron (HCCI) can be increased. To enhance the wear resistance property according to Central Composite Design (CCD), 16 samples were fabricated by varying the wt% of alloying elements. To fabricate the samples, furan sand molds were prepared and used for the further casting process. The properties of Furan sand mold enhance the mechanical properties and reduce the mold rejection rate, production time, etc. To attain the optimum Wear Rate (WR) and Impact Strength (IS) value without dominance, optimization techniques such as Response Surface Methodological (RSM) and Particle swarm optimization (PSO) are employed to solve the multi-objective problem. The RSM and PSO predicted optimum solutions are compared by using the Weighted Aggregated Sum Product Assessment (WASPAS) ranking method. The WASPAS result revealed that when compared to the RSM result, the PSO predicted optimal wt% of chemical composition (22 wt % Cr, 3 wt % Ti, and 2.99 wt % Mo) gives the optimum WR value (53 mm3/min) and IS value (3.77 J). To validate the PSO result, experiments were carried out for the predicted wt% of alloying elements and tested. The difference between the PSO predicted result and experimental result is less than 5% error which clearly shows that PSO is an effective method to solve the multi-objective problem.

Experimental investigation on influence of mould wall thickness and hardness on green sand mould permeability

The green compression strength, mould permeability and hardness are the three important properties of the green sand mould. These mould properties are influenced by the sand type, sand grain size, grain shape, clay type, water content, ramming and mould wall thickness. The poor mould permeability and hardness value result in gas related casting defect and poor casting surface finish. Hence in this work, to predict the green sand mould permeability, the exponential models are developed for mould permeability, mould wall thickness and mould hardness value. The mould specimens of 50 mm diameter, 30/40//50/60/70 mm thickness with the hardness value of 87, 90 & 93 are prepared from the moulding sand. The permeability and hardness tests are carried out in the prepared specimens. Using these test results, graphs are plotted between the permeability and mould wall thickness for 87, 90 and 93 hardness values. The exponential model for each hardness value is developed to predict the permeability value for the different mould wall thicknesses.

Analiza właściwości mechanicznych kompozytów PA6 GF30 o strukturze porowatej

The aim of the research was to experimentally determine the relation-ship between the type and content of the blowing agent and the properties of in-jection moldings made of polyamide 6 containing 30 wt.%. of short glass fibers. The experiment was carried out using a standard injection molding machine equipped with peripheral devices. Expancel 950 MB 80 and PLASTRON NUC C20-N chemical blowing agents were used as a modifier of the polyamide matrix. Based on conducted tests, it was shown that both the amount and type of the blowing agent play an important role in the properties of the tested moldings. It was found that increasing the amount of blowing agents dosed to the PA6 GF30 caused the weight reduction of the moldings and decrease of their tensile strength. A reduction in the modulus of elasticity of foamed polyamide moldings was also observed compared to the solid molded parts. It has also been shown that the impact strength of the PA6 GF30 composite changes depending on the type and amount of the blowing agent used.

Determination of cooling of Al—Si melt flow front in thin vertical cavity of ceramic shell for upper supply

The thermophysical properties of ceramic mould are experimentally determined, which made it possible to refi ne the method for calculating of the temperature of the Al—Si melt flow front when filling thin vertical cavity.