Glass Mold Research Articles

Fabrication and Characterization of Dome-Shaped Actuator Membrane for Peristaltic Valveless Electromagnetic Micropump

This paper discusses the method of fabrication and characterization of a peristaltic micropump with a dome-shaped electromagnetic (EM) actuator membrane by pouring Polydimethylsiloxane (PDMS) on top of the glass master mould. The peristaltic micropumps have three membranes separated by a spacer of 2 mm. The structure of the mould consists of three pillar-shaped glasses that have a dome-like structure at the top. The border on the edge of the mould functions as a barrier to prevent the spill of the PDMS. When the PDMS is poured on top of the glass mould, a thin membrane will be formed and it will automatically overflow to form a chamber and spacer. The fabricated membrane structures were characterized using Scanning Electron Microscopy (SEM), while the mechanical and electrica properties were analysed by observing the deformation of the membrane. The SEM images show that a hanging PDMS membrane with a thickness of 77.5 µm was established. The permanent magnet connected to the lever and attached to the membrane will interact with the magnetic field generated by the EM coil. The measurement results show that a coil of 275 turns carrying a current of 600 mA produces a magnetic field of 11 mT causing a membrane deflection of 1.5 mm. The resulting dome-shaped membrane will have its potential application for the use as the actuator for the EM peristaltic micropumps.

Formulation Development and Evaluation of Transdermal Patches of Apigenin.

Apigenin is a flavonoid that is abundantly present in fruits and vegetables. It has a diverse range of therapeutic properties, including cardioprotective, neuroprotective, analgesic, and cancer-preventive effects. Its safety profile, even at higher doses, makes the compound particularly valuable. Apigenin, along with excipients, was used to formulate patches using the solventcasting method on a glass mold. Seven distinct batches of patches were formulated using different combinations of polymers. The drug-polymer ratios employed in these formulations were (1:2), (1:3), (1:4), (1:4), (1:(2:8), (1:(1:9), and (1:(2:8) for both drugs. The formulated patches were evaluated and results indicate that the transdermal patches (TP5) have promising results.

Effect of atomic oxygen and vacuum thermal aging on graphene and glass fibre reinforced cyanate ester-based shape memory polymer composite for deployable thin wall structures

Deployable components and structures are a crucial part of space exploration. Due to fewer parts, low weight and cost, shape memory polymers (SMPs) and their composites (SMPCs) are considered ideal candidates for this. However, lower thermal stability and poor durability in the space environment have limited their applicability. This research work details the development of Graphene Nanoplatelets (GNP) filled Glass Fibre (GF) reinforced cyanate ester-based SMPC with 0/90° and ±45° sandwich fibre lay-up configuration capable of multidirectional shape programming. The SMP matrix was synthesised by mixing Cyanate Ester and Polyethylene Glycol (PEG) with added GNP. SMPC was fabricated by pouring the SMP mixture into a pre-prepared glass mould with the added GF layers. The synthesised SMPC showed shape programming and recovery at 169.01 ± 0.62 °C and stable thermomechanical properties at the temperature of 130 °C. Durability tests at extreme environmental conditions including Atomic Oxygen exposure, thermal vacuum aging, and elevated-temperature behaviour tests were conducted as these tests evaluate the durability and applicability of the SMPC for use in Earth's orbits and lunar environments. The performances of the samples before and after durability tests were measured through mechanical tests, shape memory effect tests and a series of characterisation methods such as microscopic image analysis, FTIR and dynamic mechanical analysis. According to the results, AO exposure affected the SMPCs by eroding their surface. There were no changes in the chemical structure of the SMPC yet the thermomechanical, mechanical and shape memory properties were decreased without compromising their safe operational levels such as storage onset temperatures (128.79 ± 3.08 °C), maximum tensile stress (114.99 ± 21.52 MPa), shape fixity (100 %) and recovery ratios (100 %). The erosion resistance of the GNP-filled SMPCs was improved with ∼54.35 % less erosion than the SMPC without GNP. The vacuum thermal aging slightly slowed shape recovery from 31.17 % to 8.32 % at 160 °C due to PEG crosslink degradation, however, 100 % shape recovery was achieved at the end. Further durability tests under cryogenic temperatures and effects after vacuum thermal cycles are warranted to observe the synergistic effect on the SMPC for future developments. Exploring the scalability and additive manufacturability of the developed SMPC can be advantageous in the future while mitigating challenges such as complex shape programming, long-term materials degradation, resource efficiency and compliance with safety standards.

Field-assisted sintering of MC-Ti3SiC2 composites with adjustable thermal expansion coefficient

Tool materials for precision glass moulding made of WC or SiC bear the risk of glass breakage due to a difference in the coefficient of thermal expansion (CTE) between the mould and the glass. The aim of this study is to develop a MAX phase composite with increased CTE and thus reduced CTE difference. A mixture of Ti3SiC2 and 10 vol% SiC powder was sintered between 1250 °C and 1350 °C using the field-assisted sintering technique (FAST). In addition to the sintering temperature, the dwell time and the initial particle size were varied using a full factorial experimental design. Complete densification, homogeneous carbide distribution and no grain coarsening were observed for specimens sintered at 1300 °C for 10 min at 50 MPa. The grain size of SiC and Ti3SiC2 is approximately 0.3 μm, although larger grains occasionally occur. Identified process parameters were successfully transferred to TiC reinforced Ti3SiC2 composites. While the carbide content can be specifically controlled by mixing, the MAX phase partially decomposes during sintering. MC additions between 10 and 30 vol% resulted in an adjustable CTE in the range 6.8–9.0 ppm/K.

Development of New Hard Material for High Thermal Expansion Glass Molds

Development of New Hard Material for High Thermal Expansion Glass Molds

Study on process optimization of electroless Ni-P plating on binderless WC

Abstract In the field of Precision Glass Molding (PGM), binderless tungsten carbide (WC) is a pivotal material for molds, despite its high processing costs and complexities. Nickel-phosphorus (Ni-P) alloys also exhibit superior performance at elevated temperatures. The innovation of Ni-P/WC composite molds addresses the issue of the poor machinability of WC. This research delves into the influence of the activating solution’s concentration on the surface activation energy of WC, the quality of plating, and the deposition rate during the electroless Ni-P plating process. Additionally, the study scrutinizes how the pH level of the plating solution impacts the quality of Ni-P, the rate of deposition, and the phosphorus content. These investigations have led to the realization of an efficient and high-quality Ni-P plating process for WC.

Hydrogen Sensor with a Thick Catalyst Layer Anchored on Polyimide Film

AbstractHydrogen sensors are important in a hydrogen‐driven society to prevent explosions caused by hydrogen leaks into the atmosphere. In previous studies, resistive hydrogen sensors on polymer films have metal oxide nanostructures decorated with novel metals that enable good responses at room temperature. However, the in situ growth process of sensing nanostructures has the disadvantage of ineffective fabrication, particularly when preparing a thick catalyst layer to produce reliable readouts from the catalytic hydrogen combustion. This work presents a catalytic combustion hydrogen sensor with a thick catalyst layer anchored in a UV resin layer on polyimide film. Catalyst anchoring channels are made by UV imprinting with a glass mold. The sensor consists of a sensing electrode and a microheater, both made of Au within an area of 1.2 mm diameter. UV imprinting produces a UV resin layer of 27 µm thick and catalyst anchoring channels of 14 µm deep and 20–30 µm wide, which are filled with Pt/TiO2 as a catalyst. The sensing response is 7.9% for 1% H2 under ambient conditions, and the detection range is 0.1–3% H2. The UV‐resin microstructures can effectively retain a thick catalyst layer to enhance sensitivity, and their low thermal conductivity reduces heat loss.

Bioinspired Lubricity from Surface Gel Layers.

Surface gel layers on commercially available contact lenses have been shown to reduce frictional shear stresses and mitigate damage during sliding contact with fragile epithelial cell layers in vitro. Spencer and co-workers recently demonstrated that surface gel layers could arise from oxygen-inhibited free-radical polymerization. In this study, polyacrylamide hydrogel shell probes (7.5 wt % acrylamide, 0.3 wt % N,N'-methylenebisacrylamide) were polymerized in three hemispherical molds listed in order of decreasing surface energy and increasing oxygen permeability: borosilicate glass, polyether ether ketone (PEEK), and polytetrafluoroethylene (PTFE). Hydrogel probes polymerized in PEEK and PTFE molds exhibited 100× lower elastic moduli at the surface ( = 80 ± 31 and = 106 ± 26 Pa, respectively) than those polymerized in glass molds ( = 31,560 ± 1,570 Pa), in agreement with previous investigations by Spencer and co-workers. Biotribological experiments revealed that hydrogel probes with surface gel layers reduced frictional shear stresses against cells (τPEEK = 35 ± 15 and τPTFE = 22 ± 16 Pa) more than those without (τglass = 68 ± 15 Pa) and offered greater protection against cell damage when sliding against human telomerase-immortalized corneal epithelial (hTCEpi) cell monolayers. Our work demonstrates that the "mold effect" resulting in oxygen-inhibition polymerization creates hydrogels with surface gel layers that reduce shear stresses in sliding contact with cell monolayers, similar to the protection offered by gradient mucin gel networks across epithelial cell layers.

Customer Demand Forecast Using Time Series Approach

Nowadays we are living in an uncertain time (pandemics, wars, inflation, shortages) and for companies, predicting the future of the business becomes more and more difficult. From this point of view, we can resort to statistical forecasting methods that, based on on past data and current external trends, can predict figures for the short and long term planning. The motive, the scope, behind this study is to develop a forecasting model using time series that can help the organisations and the managers in taking better decisions, on time, for the future of the company. The data that were used for this paper are focusing on forecasting the demands for the sales budgets only, starting with the historical data from a company in the glass mould manufacturing area. If we examine the current literature, we can find that there a few studies, with real business data regarding budgeting, therefore this study is relevant and important for the researchers and practitioners. This paper aims to illustrate how we can use the time series statistical method and the linear equation regression that can help the organisations to forecast and plan the business. The main findings after developing the model are that it allows smoothing the fluctuations of the series over time (especially if we find outliers) and eliminating the influence of seasonality, in order to obain in the end a good accuracy of the predictions. In order to measure the quality of the forecasting we can use many indicators, such as Mean Absolute Percentage Error.

Fiber Bragg grating detection of gel time and residual strain of curing in epoxy resins

AbstractThe curing shrinkage of epoxy resin can generate residual strains and internal stresses that reduce the material's strength and life. In this paper, a thermocouple‐compensated fiber grating detection method for the gel time and residual strain in epoxy resin is proposed. The strain evolution and glass transition temperature of E51/W93 epoxy systems with different Al2O3 contents cured at 30°C are detected by fiber Bragg gratings and DSC tests. The generation mechanism of residual strain in epoxy resin filled with Al2O3 fillers is studied. The gel time, gel temperature and residual strain of epoxy resin can be measured by this method. The results show that the cure shrinkage of epoxy is affected by chemical shrinkage, thermal expansion or shrinkage, and demolding, resulting in residual strain of the material after curing. Moreover, the glass mold has a great interference with the curing shrinkage of epoxy. The Al2O3 filler can prolong the gel time of E51/W93 epoxy systems, and reduce the exothermic peak temperature of curing. When the content of Al2O3 filler exceeds 44.44 wt.%, the low proportion of epoxy and the thermal conductivity of the filler make the curing shrinkage of epoxy during the heating stage mainly affected by chemical shrinkage. The glass transition temperature of the epoxy with Al2O3 content of 70.59 wt.% is the maximum, and the residual strain is at a low level. This method is helpful to analyze the curing shrinkage characteristics of materials, and is of great significance for evaluating the properties of epoxy cured products and guiding the optimization of material parameters.Highlights A method for measuring the gel time and residual strain of curing in epoxy resin is proposed. The study focuses on the detection of key parameters during the curing of epoxy resins with different Al2O3 contents. The aim is to analyze the curing shrinkage and residual strain generation mechanism of epoxy resin filled with different contents of Al2O3.

유리 렌즈의 열 성형 공정 조건 도출을 위한 수치해석 연구

유리 렌즈의 열 성형 공정 조건 도출을 위한 수치해석 연구

A New Polymeric Minimally Invasive Glaucoma Implant

AbstractGlaucoma drainage devices are implanted in the eye to treat glaucoma, a disease that can cause vision loss and blindness. These devices are designed to reduce intraocular pressure (IOP), a major risk factor for the progression of glaucoma, by providing an alternative outflow path for the fluid produced by the eye, the aqueous humor. Here, a novel polymeric minimally invasive glaucoma implant designed to enhance aqueous humor outflow is demonstrated. The implant is made of a unique, potentially biodegradable thermoplastic material, polycarbonate bisamide (PC‐BA), and produced through replica molding using hot embossing and femtosecond laser‐machined glass molds. Post‐mortem experiments demonstrate successful device implantation into a rabbit's eye, with the implant remaining securely in place. Although the mass loss and changes in molecular weight observed in the in vitro degradation experiments are not significant within the tested times and degradation conditions, the PC‐BA is a slow‐degradation polymer that may take a few years to fully degrade. Thus, the implant will also slowly degrade and be absorbed by the body over time, leaving behind a natural outflow pathway. This potentially biodegradable glaucoma implant may represent a promising new approach for restoring outflow in a more natural way.

Investigation of Surface Integrity Induced by Ultra-Precision Grinding and Scratching of Glassy Carbon.

Glassy carbon provides material characteristics that make it a promising candidate for use as a mould material in precision glass moulding. However, to effectively utilize glassy carbon, a thorough investigation into the machining of high-precision optical surfaces is necessary, which has not been thoroughly investigated. This research analyses the process of material removal and its resulting surface integrity through the use of nano-scratching and ultra-precision grinding. The nano-scratching process begins with ductile plastic deformation, then progresses with funnel-shaped breakouts in the contact zone, and finally concludes with brittle conchoidal breakouts when the cutting depth is increased. The influence of process factors and tool-related parameters resulting from grinding has discernible impacts on the ultimate surface roughness and topography. Enhancing the cutting speed during cross-axis kinematic grinding results in improved surface roughness. Increasing the size of diamond grains and feed rates leads to an increase in surface roughness. An achievable surface roughness of Ra < 5 nm together with ductile-regime grinding behaviour meet optical standards, which makes ultra-precision grinding a suitable process for optical surface generation.

Microstructural and Mechanical Characterization of Large Surfaces after Laser Cladding by Wavering of Nickel Coating on Cast-Iron Molds Used in Glass Industry

Laser cladding of a Ni based powder on cast iron is performed by a 4kW continuous diode laser. For this, a robot programming method named “Wavering” is used. Indeed, this method allows to cover large surfaces (width higher than 5 mm and thickness higher than 4 mm). The cast iron substrate used during this work is employed for its thermal properties in glass mold Industry. However, it has drawbacks which are weak wear, corrosion, and abrasion resistance. Conventional techniques used to protect the molds, like Plasma Transferred Arc (PTA), affect the molds microstructure, but also the thermal and mechanical properties. The laser cladding of the Ni based alloy allows to protect the molds without affecting the cast iron thermal properties (low Heat Affected Zone). The purpose of this research is to produce a well bonded Ni based melted powder without pores or cracks on large and curvilinear surfaces. First, the coating, adapted to this substrate geometry, is optimized. Then, an investigation of the impact of the processing parameters (power, scanning speed and wavering frequency) on the microstructure is carried out. Besides, the mechanical behaviour is analysed by microhardness. In addition, the evolution of the Heat Affected Zone (HAZ) according to the processing parameters is observed. Two kinds of areas are inspected in terms of microstructure: a stable area obtained after a single pass and an interferenced area linked to superimposed passes. Those analyses led to a cladding parameter optimization to obtain perfect bonding, to avoid porosity propagation and to limit the HAZ emergence on curvilinear surfaces. Finally, in comparison with the PTA technique, it appears that laser cladding process with wavering method leads to a good coating of curvilinear surfaces.

Inhomogeneous thermal analysis of microlayer mold for glass molding of fast-axis collimation lens array

Fast-axis collimation (FAC) lens arrays play a crucial role in laser systems, offering precise beam shaping and focusing for applications such as laser marking, and optical communication. Achieving high precision in these applications requires a FAC lens array with a long Rayleigh range. While precision glass molding with nickel-phosphorus (Ni-P) microlayer molds has revolutionized the mass production of FAC lens arrays, the extreme conditions during the molding process can lead to poor profile accuracy. To address this issue, we developed an optical collimation system to derive the final characteristic parameters and obtain the beam waist radius and Rayleigh range of the collimated laser. Additionally, we conducted a thorough analysis of the inhomogeneous thermal expansion process of the microlayer mold and established a mathematical solution for thermal compensation to modify the mold's shape. We validated the proposed method by fabricating an FAC lens array mold and measuring the profile error and waist radius of a molded FAC lens array. We also calculated the profile error of this method using a finite element (FE) model in ABAQUS. The results indicate that incorporating the inhomogeneous thermal expansion reduces the shape error of the FAC lens array from 0.577 μm to 0.135 μm. Moreover, using inhomogeneous thermal compensation significantly improves the Rayleigh range of the FAC lens array from 1.285 μm to 9.8 × 104 μm.

EFFECT OF PERCENTAGE OF RESIN AND CATALYST OF FIBERGLASS FIBER COMPOSITES, WITH FIBER ORIENTATION DIRECTIONS (0°,45°), (45°,90°) AND (0°,90°) ONTENSILE AND IMPACT STRENGTHS

In the world of aviation industry the use of composite materials began to be widely developed, one of the most frequentlyused composite materials in the industrial world is composite material with fillers in the form of Fiberglass. Currently,fiber-reinforced composite materials are widely used engineering materials because of their specific strength and stiffness which are far above engineering materials in general, so that their properties can be designed close to the needs. The research conducted used WR 200 Fiberglass with fiber direction orientation treatment (0°, 45°), (45°, 90°), (0°, 90°), with 1%, 1.5%, 2% catalyst. The manufacture of composite workpieces/specimens using the hand lay-up methodwith glass molds measuring 22 cm × 17 cm × 0.4 cm and 10 cm × 5 cm × 1 cm. Based on the tensile and impact tests carried out on the WR 200 fiberglass composite, the tensile test obtained the results with the treatment of fiber direction orientation 45 °, 90 ° with 1% catalyst composition getting the highest tensile strength value of 56.87 N / mm2. The treatment of 0°,90° fiber direction orientation with 2% catalyst composition got the lowest tensile strength value of 38.15 N/mm2. In the impact test, the results obtained with the 45°,90° fiber direction orientation treatment with 1% catalyst composition obtained the highest Fracture Stress value of 9.687 Joules and the highest Tenacity Price value of 0.121 Joules/mm2. The 0°,90 fiber direction orientation treatment with 2% catalyst composition got the lowest fracturestress value of 3,935 Joules and the lowest ductility price value of 0.049 Joules/mm2.

Compositional and structural study of B2O3–La2O3–Ta2O5–SiO2 glasses for high refractive index optical lenses

High-refractive index glasses are used to produce glass lenses by the precision optical Glass Mold Press (GMP) process and have been extensively studied because of increased demand for their application in telecommunications, optical lenses, and cameras. Borate glasses containing Ta2O5, Nb2O5, La2O3 and Gd2O3 have mainly been used as materials for GMP because of their excellent optical properties and low production cost. This study conducted a systematic investigation of the B2O3–La2O3–Ta2O5–SiO2 quaternary glass system for precision GMP applications. The glass forming range of the quaternary system was studied using (B2O3+SiO2)–La2O3–Ta2O5 and changes in physical and thermal properties such as refractive index, density and glass transition temperature of the obtained glasses were examined. Compositional dependent structural changes were also inspected by Raman spectroscopy and solid state nuclear magnetic resonance (NMR) analyses, to determine the compositions’ effect on thermal and optical properties.

Shaking table test to investigate the size effect on the seismic response of a low-cost friction pendulum system

To enhance the seismic resilience of reinforced concrete (RC) bridge piers, a novel friction pendulum system was developed. It consisted of a friction pendulum and a spherical sliding surface that were constructed from conventional steel and concrete. In comparison to commercial isolators, the complex spherical shape was realised using a three-dimensional printer to fabricate an acrylic glass mold, which allowed a significant cost savings in production. The system was distinguished by stable oscillation and a significant reduction in response accelerations on the flat surface. The inclined part acted as a restoring force that limited the residual displacement. However, these properties were confirmed experimentally using only small specimens. To characterise the fundamental properties of the system, a bidirectional shaking table test was performed in this study to investigate the size effect on the seismic performance of the proposed system. The test results demonstrate that the excellent performance in reducing the response acceleration and residual displacement is independent of the specimen size. In addition to the dependency of the friction coefficient on the sliding velocity and axial pressure, the impact force was observed to increase with the superstructure weight. Furthermore, a simplified method for estimating the maximum and residual displacements of the proposed system is presented.

Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry

ObjectivesThe aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content.MethodsResin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05).ResultsAfter polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content.ConclusionsA high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites.Clinical significanceThe type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.Graphical

Studies on Protective Coatings for Molding Tools Applied in a Precision Glass Molding Process for a High Abbe Number Glass S-FPM3

Precision glass molding (PGM) is an efficient process used for manufacturing high-precision micro lenses with aspheric surfaces, which are key components in high-resolution systems, such as endoscopes. In PGM, production costs are significantly influenced by the lifetimes of elaborately manufactured molding tools. Protective coatings are applied to the molding tools to withstand severe cyclic thermochemical and thermomechanical loads in the PGM process and, in this way, extend the life of the molding tools. This research focuses on a new method which combines metallographic analysis and finite element method (FEM) simulation to study the interaction of three protective coatings—diamond-like carbon (DLC), PtIr and CrAlN—each in contact with the high Abbe number glass material S-FPM3 in a precision glass molding process. Molding tools are analyzed metallographically using light microscopy, white light interferometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The results show that the DLC coating improved process durability more than the PtIr and CrAlN coatings, in which the phenomenon of coating delamination and glass adhesion can be observed. To identify potential explanations for the metrological results, FEM is applied to inspect the stress state and stress distribution in the molding tools during the molding process.