Resin Mold Research Articles

Effectiveness of polyacrylic acid-bioactive glass air abrasion preconditioning with NovaMin remineralization on the microhardness of incipient enamel-like lesion.

Background:Bioactive glass (BAG) remineralization is a promising method for dental hard tissue regeneration. The aim of this study was to evaluate the microhardness of incipient enamel-like lesions with or without preconditioning by air abrasion using polyacrylic acid (PAA)-BAG before application of NovaMin remineralizing agent.Materials and Methods:Forty extracted human molars were selected, sectioned mesiodistally obtaining buccal and lingual halves, and embedded in resin molds. Specimens were randomly assigned to four groups (n = 10) according to the remineralization protocol: G1 (control, artificial saliva), G2 (preconditioning), G3 (NovaMin), and G4 (preconditioning and NovaMin). Enamel windows 4 mm × 4 mm were done on the buccal and lingual surfaces. Specimens were immersed in a daily renewed demineralizing solution to create white spot lesions. Remineralizing agents were applied according to the manufacturer's instructions, and specimens were stored in a daily renewed artificial saliva. Microhardness was assessed using Vickers hardness number (VHN) at baseline (positive control), after demineralization (negative control), and after 24-h and 1-month remineralization.Results:The preconditioning/NovaMin group after 1 month showed a statistically significant high VHN, with no statistically significant difference between it and the positive control. This was followed by the NovaMin group after 1 month, while the lowest VHN was found in the demineralized group, with no statistically significant difference between it and the preconditioning group, whether after 24 h or 1 month.Conclusions:Enamel preconditioning with PAA-BAG air abrasion play a major role in enhancement of remineralization when it is accompanied with NovaMin. Furthermore, an extended period of time had helped to attain more benefits from NovaMin remineralization.Clinical Significance:Enamel remineralization with NovaMin after conditioning by bioactive glass air abrasion, provides the patients with a fast and durable treatment of incipient enamel lesions, which would reduce the possibility of future progression of demineralization and caries occurrence.

High-throughput three-dimensional spheroid tumor model using a novel stamp-like tool

Spheroid culture is a widely used three-dimensional culture technology that simulates the three-dimensional structure of tumors in vivo and has been considered a good model for tumor research. However, current commercialized spheroid culture tools have the shortcomings of high cost or relatively poor spheroid-forming results for some special cells. To solve such problems, we designed a 3D printed, reusable, stamp-like resin mold that could shape microstructures for spheroid culture of tumor cells on the surface of agarose substrate in a 96-well plate. We applied this homemade three-dimensional culture tool in spheroid formation for hepatocellular carcinoma cells. The experimental data show that the effect of spheroid culture on four hepatocellular carcinoma cell lines in our homemade spheroid culture plate is better than that of the commercialized ultralow attachment spheroid culture plate, and compared to two-dimensional culture, three-dimensional culture improves cell functions. In addition, the drug-sensitive test based on patient-derived hepatocellular carcinoma cells showed a different pattern between spheroid and two-dimensional cultures. In conclusion, our spheroid culture tool is characterized by its low cost, reusability, low cell consumption, convenience in medium exchange, and good effect of spheroid formation, suggesting that this technique could be widely used in individual treatment and high-throughput drug screening.

Sanitary-ware factories: heat recovery strategies to optimize energy and water consumption

Sanitary-ware manufacturing has a specific particular configuration of energy consumption from the thermal point of view. Heat requirements and temperature levels through the different sub-processes in the manufacturing sequence are distributed in such a way that a proper network of recovered heat can save up to 1/3 of the primary energy consumption of the factory. A half of the total thermal requirement is devoted to fire the ware along a tunnel kiln that exhausts ¾ of this heat through the exhausting and cooling stacks at a temperature a proper temperature level to be recovered in the rest of common thermal processes as drying or heating. On the other hand, the great water consumption to flush resin molds can be saved by a multi-effect distillation treatment fed with recovered heat. Instead of rejecting it with solved salts, a combined power plant optimally sized can be coupled to match both, electrical and thermal consumptions allowing for extra heat to distillate the flushing water. This research shows how sanitary-ware manufacturing can be re-engineered to save most of the water and 31 percentof primary energy

The difference in enamel surface hardness after immersion process with cocoa rind extract (Theobroma cacao) and fluoride

Aims: Enamel is the hardest tissue in the human body and possessing mechanical properties, such as physiological functions as chewing, while protecting the underlying structure. Fluoride increase and improve one of the mechanical properties which is tooth surface hardness, but the excessive use of fluoride has the risk of fluorosis. Theobromine in cacao rind extract could potentially be used as an alternative herbal ingredient. Theobromine increases tooth enamel surface hardness through interstitial reactions. The aim of this study is to analyze differences in the hardness of the enamel surface by immersing it in extract of cacao rind and fluoride. Materials and Methods: The dental crowns of 27 square-shaped bovine incisors were planted in a round-shaped resin mold and divided into three groups consisting of nine samples. The control group was immersed in artificial saliva, Group I was immersed in artificial saliva with 0.1% of theobromine cacao rind extract, while Group II was immersed in a combination of artificial saliva and 2% sodium fluoride (NaF). The measuring of surface hardness was performed using Wolpert Wilson Vickers Microhardness tester after the sample had been immersed in the incubator for 30 min at 37°C. Results: Those groups immersed in artificial saliva to which 0.1% theobromine cacao rind extract was added yielded the highest surface hardness. The surface hardness of groups immersed in artificial saliva with the addition of 2% NaF was higher than that of the artificial saliva group. Conclusions: There was significant difference in the tooth enamel surface hardness of the groups immersed in cacao rind extract compared with that of the fluoridated groups.

Study on Resin Mold for Injection Molding Utilizing 3D printer (AM).

Study on Resin Mold for Injection Molding Utilizing 3D printer (AM).

Heat recovery in sanitary-ware industry applied to water and energy saving by multi-effect distillation

Sanitary-ware industry, as a sub-sector in the ceramic industry, is a great consumer of energy and water, although there are some opportunities to reduce the global consumption, especially for factories based on resin molds technology. This research aims to show the way to reduce drastically water consumption by recovering waste heat into a multi-effect distillation system to re-use most of the flushing water. This solution improves both, the environmental and economic performance of this industry. The proposed configuration is a multi-effect distillation (MED) adapted to run with recovered heat from the kiln exhausting. The efficiency of the system is improved by recovering the heat of the gas mixture leaving the first effect in the pre-heater of the feeding water. The research lays on the computerized simulation of the coupled systems run under different parameters. Mathematical and thermodynamic models have been developed to simulate the behavior of the system. The obtained results show the optimal configuration depending on the thermal variables which could achieve up to almost 92% of the needed water against conventional technology. The system can be applicable to new or existing factories based on resin molds technology and this research may contribute to reduce consumption of resources and thus, the environmental impact.

Fabrication of Line & Space Structure and Wiring on 3D Surface Features with Imprinting Process

In this study, we have investigated the wiring on the curved surfaces with nanoimprint technology using the flexible resin mold. The maximum transfer ratios of line & space structures of polyetherimide (PEI) and cyclic olefin copolymer (COC) were higher than 93% by using thermal nanoimprint process. It found that the silver nano-ink can be transferred to the curved surfaces using the UV curable resin as the adhesive material. The wired on curved surfaces using a flexible polymer mold, silver nano-ink, and UV curable resin as an adhesive showed the electrical conduction indicated. Therefore, the possibility to apply nanoimprint technology to wiring on three-dimensional surface features was indicated.

Real-Time Temperature Sensor Based on In-Fiber Fabry–Perot Interferometer Embedded in a Resin

A simple to fabricate, cost-effective, robust, and highly accurate fiber optic temperature sensor is proposed and experimentally demonstrated. The sensor head consists of an in-fiber Fabry–Perot interferometer (FFPI) embedded in a mold made of a polyester resin. FFPI, which in general present good strain sensitivity and low-temperature sensitivity, was assembled by splicing a microsegment of capillary fiber of 14.66 μ m between two single-mode fibers. The reflected spectrum of the FFPI exhibited a single interference dip within a span of 80 nm. The dimensions of the resin mold can be modified by changing the ambient temperature, which in turn changes the length of the FFPI air-cavity. The dip of the reflected spectrum is shifted toward shorter (larger) wavelengths when external temperature is decreased (increased). The large free spectral range (FSR) allowed to monitor the temperature changes by either a wavelength or an intensity interrogation scheme. Using a laser and an optical power meter it was possible to demonstrate a real-time temperature sensor with a sensitivity of −60.79 nW/°C and a resolution of 0.5 °C, in the range of 10–30 °C. We believe that the practicality of this real-time sensor can be very attractive for environmental sensing application.

Compressibility of weft knitted reinforcement fabrics from glass yarn

Compression, and relaxation of a reinforcement fabric during composite manufacturing dictates mold design, resin flow, and fiber volume fraction of resultant composite; and single layer fabric architecture, and numbers of layers in a fabric stack change the compressibility character of overall reinforcement material. This study dealt with the effect of knit architecture and number of layers on dry compression and relaxation responses of weft knitted fabrics from glass yarn. Fabric architectures of 1x1, 2x2, English, and Fisherman ribs were selected. The thicknesses of single-, double-, and triple-fabric layers from same knit architectures were measured under compression and recovery pressures ranging from 2 to 200 kPa. Areal densities of single layer fabrics were measured. 2x2 and fisherman rib fabric architectures exhibited higher thickness, areal density and fiber volume fraction than 1x1 and English rib fabric architectures due to their nested and compact structures. Due to nesting between adjacent layers; multi-layer fabrics demonstrated higher fiber content than single layer fabrics. The difference between the compression and recovery thicknesses proved the existence of dissipated energy. Compression curves - the relationship between fiber volume fraction and compression pressure - classified by number of layers were fitted by square equation with fairly high determination of coefficients (R2).

Integrated System of Thermal/Dimensional Analysis for Quality Control of Gray and Ductile Iron Castings Solidification

The main objective of the present work is to introduce a specific experimental instrument and technique for simultaneously evaluating cooling curves and expansion/contraction of cast metals during solidification, adapted for commercial foundry use. The recorded data are processed using specialized software, which conveniently displays both cooling and contraction/expansion curves and their specific parameter values. Experiments compared hypoeutectic gray (GI) and ductile (DI) irons with white (WI) irons. Three important moments were found on the expansion/contraction-cooling curves: the start of eutectic freezing, the point of maximum expansion and the end of solidification. All of the tested irons have similar values for initial expansion up to the start of eutectic freezing (0.44%) due to the ferrostatic pressure, silica sand mold expansion, mold movement, etc. The maximum expansion, reached between the temperature of eutectic recalescence and the end of solidification, depends on the carbides/graphite ratio and graphite morphology: WI-0.465%, GI-0.552%, DI-1.032%, as averages. Graphitic expansion, absent for WI, increased to 0.109% (GI) and up to 0.596% (DI). For both GI and DI, the expansion at the end of solidification is only 6% lower compared to the maximum level, while for WI it decreased more than 50%. Specifically, the acceleration rate of the graphitic expansion up to the maximum level (Kgr1) is different compared with its deceleration to the end of solidification (Kgr2), and also are different for irons being tested, GI versus DI. Nodular graphite led to the (Kgr1) factor being 2.5 times higher, compared to GI, whereas only a slight difference was observed between GI and DI for the Kgr2 factor. Higher graphitic expansion in DI led to higher shrinkage sensitivity, compared to GI, as measured in furan resin mold test castings.

Fabrication of Complex Shaped Ceramic/Metal Parts by High-speed Centrifugal Compaction Combined with Three-dimensional Printed Resin Molds and Cores

Fabrication of Complex Shaped Ceramic/Metal Parts by High-speed Centrifugal Compaction Combined with Three-dimensional Printed Resin Molds and Cores

Development of a Large-Area Hot Embossing Mold with Micro-Sized Structures

Microtechnology is a core technology in the 21st century. Microfabrication plays an important role in the precision machinery industry. Two major troublesome issues in the mold industry are the time and expense needed for producing a mold for the pilot run in the new product development phase. The aim of this study was to propose a cost-efficient method for fabricating a large-area hot embossing mold with micro-sized structures. The advantages of this method include short manufacturing leading times, simple manufacturing processes, low manufacturing cost, and short processing time. A large-area hot embossing mold with areas of 250 mm × 350 mm was fabricated. Cost savings about 61.3 % can be reached. The manufacturing processes developed in this work possess a significant industrial application value because a new 3C product with surface texture could be reached with a large-area epoxy resin mold using hot embossing molding. DOI: http://dx.doi.org/10.5755/j01.ms.24.4.14991

Fabrication of the Fresnel lens with liquid silicone rubber using rapid injection mold

Liquid silicone rubber (LSR) parts are used in aerospace application due to their stable properties. In order to compress time to market for a new product, it is necessary to develop an injection mold for LSR injection mold swiftly and effectively. Rapid tooling (RT) technology can reduce time to market compared to the conventional machining methods. The aluminum-filled epoxy resin mold is capable of replacing the conventional steel mold for small batch production using injection molding. In this study, an injection mold with heating element was developed using RT technology for LSR injection molding. It was found that the replication rate for the average microgroove depth and width of the Al-filled epoxy resin mold is about 90.5% and 98.9%, respectively. The transcription rate for the average microgroove depth and width of the LSR molded parts is about 91.5% and 99.2%, respectively. The variations in dimension of microgroove depth and width of the LSR molded parts can be controlled within ± 1 μm. The average surface roughness of the Al-filled epoxy resin mold was only increased by about 12.5 nm after 200 test runs of LSR injection molding.

Tensile behavior of aloe vera fiber reinforced epoxy and polyester resin matrix composites

PurposeThis paper aims to investigate the tensile behavior of epoxy and polyester matrix composites reinforced with continuous and aligned aloe vera fibers.Design/methodology/approachComposites with different volume fractions (30, 40 and 50 Vol. %) were fabricated by laying the fibers in a steel mould and pouring liquid resin, either DEGEBA/TETA epoxy or methyl-ethyl ketone hardened orthophthalic polyester, under pressure of 3 MPa. The specimens were cured for 24 h at room temperature and then tested in a universal Instron testing machine, model 5582, at 298 K (25°C).FindingsThe fracture surface was analyzed by scanning electron microscopy (SEM) under an acceleration voltage of 15 kV. SEM fractography revealed a poor adhesion between both the epoxy and polyester matrices with the aloe vera fiber. The results showed that in both cases the introduction of aloe vera fibers had a minor effect on the matrix reinforcement.Originality/valueInvestigation and comparison of tensile behavior of epoxy and polyester matrix composites reinforced with continuous and aligned aloe vera fibers have not been attempted so far.

Nano-Enabled Microinductors for Power Electronics Microfabricated By Advanced Heterogeneous Integration

Novel nano-enabled microinductors for power electronics using advanced heterogeneous integration have been developed. These toroidal microinductors employ a first-of-its-kind nanocomposite magnetic core material employing superparamagnetic iron nanoparticles that are covalently cross-linked. This nanocomposite has high resistivity, is mold injectable, and can be cured at low temperature (63 °C) making it better suited for microfabrication than current, state-of-the-art ferrite core materials. The coil is micromachined out of electroformed copper consisting of top, inner/outer, and bottom winding layers. Two unique methods are used to form the electroplating molds for the inner/outer windings to accommodate thick core layers demonstrating two different ways these microinductors can be made. The first method employs high-aspect-ratio 3D printed resin molds instead of standard photoresist. The second method uses the non-conducting nanocomposite core itself as the plating mold and patterning is performed via femtosecond laser micromachining. These Sandia developed technologies enable new, low-cost, advanced heterogeneous integration schemes for creating high performance, nano-enabled microinductors that are radically different than previous attempts using LIGA or other costly, non-optimal microfabrication techniques. 2 μH output and 500 nH input microinductors for use in a high performance buck converter are showcased. Both inductors have 50 wire turns and less than 1 cm3 form factors. A process flow outlining the steps needed to realize these devices is provided. This flow takes advantage of the molding capabilities of our iron nanocomposite core material, the high electrical conductivity of electroformed copper, and the high-aspect-ratio capabilities of 3D printing and femtosecond laser micromachining. Initial characterization results over frequency are presented for this unique set of power inductors.

Fabrication of polymeric dual-scale nanoimprint molds using a polymer stencil membrane

We report on a simple and effective process that allows fabricating polymeric dual-scale nanoimprinting molds. The key for the process is the use of a thin flexible SU-8 stencil membrane, which was fabricated by either photolithography or thermal nanoimprint lithography (NIL). The stencil membrane with microscale pores was assembled into a nanopatterned substrate, producing a dual-scale structure. The assembled structure was used as a template to produce polymeric imprinting molds via UV-NIL. With this method, we demonstrated dual-scale nanoimprint molds having nano-pillars of 251 nm diameter and 146 nm high on top of microscale square protrusions of 5 μm wide and 3.6 μm high. The resin mold with the dual-scale structure was successfully used to produce a freestanding membrane with dual-scale perforated pores via UV-NIL. After metal coating and integrated into microfluidic devices, this freestanding membrane can potentially be used as a substrate for surface plasmon resonance sensors.

Management tool to optimize energy and water consumption in the sanitary-ware industry

Abstract Over the years the ceramic industry has been widely studied. However, little attention has been devoted to the particular area of sanitary-ware manufacturing, although it is a great consumer of energy and water. The aim of this research is to analyze and quantify how and where energy and water are consumed by mapping the whole process. Once the key points and amounts of consumption are located, a global map of single flows is established by thermodynamically modeling every relevant sub-process as a balance of mass and energy. The research focuses on demonstrating that this modeled map can be optimized by diverting energy flows from one sub-process to another searching for the minimum incoming energy within the global process, which derives in a minimization of residual energy, waste water and emissions. Results show that almost one third of the energy and emissions can be saved and more than a half of the water can be saved as well in the resin mold technology of manufacturing. This research provides a tool to know how the resources are consumed in the sanitary-ware industry and show the possibilities to reduce them as well as the global impact.

Probabilistic risk-based pollution prevention model for a foundry: a case study of casting.

Hazardous air pollutants from industrial activities have long been associated with serious health effects. Traditional health risk assessment uses point estimates of inhalation concentrations based on standard Gaussian diffusion models with steady-state emission rate assumptions. This traditional approach was criticized because it does not account for variability and thus leading to a potential overestimate of the health risk from the batch processes. To overcome this deficiency, a probabilistic risk assessment model is proposed. The foundry industry with processes typically associated with several hazardous air pollutants is identified and iron casting is chosen as a case study to compare risk estimates. Existing data, representing historical proprietary information of the case study, were used to deliver representative risk values and help identify potential replacements or interventions in the manufacturing process. A probability distribution function of emitted concentrations was simulated to model the batch process emissions from mold and core resin binders, a major source of pollution. The same method was applied to exposure factors to feed into the risk model resulting in a probabilistic risk evaluation. Several alternative resin binders in commercial use were examined to offer a risk-based substitute to the resin binder in use. The risk results provided an opportunity to consider newer and environmentally friendlier options. A comparison of the resultsfrom this approach and those from the point estimate analysis reveals a gross over estimation of risks. The point estimate risk values were about eight time larger than the mean value and about twice the 95th percentile values of the probabilistic risk approach. The wide range of variability among resin binders associated risk results, close to two orders of magnitude in some cases, presented opportunities to select from a variety of binders with lesser emissions and lower risk. Optimal selection will depend on several pollutants emitted from this process to help address cumulative impacts of multiple pollutants. Investigations are underway for a multi-pollutant strategy including trade-offs, and other quality controls vital to the decision-making.

Process factors affecting adhesion of encapsulation molding compounds

PurposeThe purpose of this paper is to determine the key process factors which affect the adhesion strength of encapsulation molding compounds (EMCs) to leadframes to obtain reliable components without any need to pretreat the leadframe surface.Design/methodology/approachEMCs were molded to Cu leadframes to experimentally quantify the effect of mold temperature, resin viscosity, leadframe oxidation and powder moisture on the adhesion force. Component reliability was assessed by PCT.FindingsA higher mold temperature result in a larger adhesion force. The mold temperature of 175°C provides the largest process window. Leadframe oxidation can increase adhesion first, but then decrease it drastically with further oxidation. The powder moisture content has mixed effect on adhesion.Practical implicationsBy molding at 175°C, limiting the wire bonding time and minimizing the powder moisture content, reliable components can be obtained without any need for leadframe surface pretreatment such as plasma cleaning or surface coating.Originality/valueQuantify the key process factors which affect the adhesion of EMCs and reveal reason behind the current industrial practice of using the mold temperature of 175°C.

Investigation of effects of phosphor particles on optimal design of surface‐mount‐device light‐emitting diode packaging using ray‐tracing simulation

This study presents investigation of effects of phosphor particles on optimal structure and optical design of surface-mount-device (SMD) light-emitting diode (LED) packaging (PKG) using ray-tracing simulation. In the authors’ previous study, effects of the reflection properties of the PKG resin and the lead-frame silver plating on the light extraction efficiency was investigated, and the optimisation method of the cavity angle composing the light reflector of the PKG was proposed. In this study, the optimal cavity angle and reflection properties under the condition of phosphor particles present in mould resin of the top-view PKG are investigated. In addition, the better conditions of the reflection properties under the conditions in which the phosphor is contained and not contained in the mould resin are confirmed. Finally, an optical design method of the SMD LED PKG with the mould resin containing a phosphor is proposed on the basis of the simulation results.