Resin Mold Research Articles

An Affordable Knee Arthroscopy Simulator

Abstract: Introduction: The objective of this study is to describe a model of knee arthroscopy simulator that is affordable, low-cost and easily reproducible, aiming to enable the diffusion of more effective active teaching and training methodologies. Methods: For the creation of the arthroscopic camera, an endoscopic camera for mobile phones and computers model SXT-5.0M manufactured by KKMOON were used. The camera was introduced in a metal tube, which was coupled to a set of three 20 mm PVC hydraulic connectors to simulate the handle and sleeve of the arthroscope. The camera has a resolution of 1280 x 720 pixels and is equipped with six built-in white LED lamps, simulating and eliminating the need to use an additional light source. The knee model was developed using a PVC pipe fixed on a wooden support, to which synthetic femur and tibia models were affixed. Four three-centimeter diameter holes, compatible with the standard arthroscopic portals, were made in the body of the PVC pipe. For the menisci, a model was made out of modeling clay (Corfix®), until the anatomical structures were close to the real ones. The model consists of both menisci and the intercondylar eminence, simulating the proximal tibial articular surface. The model made out of modeling clay was the basis for the production of a thin Crystal Polyester Resin mold. Using the resin mold, the meniscal models were made of Silicone Rubber Type II, widely used in industry and crafts. Results: A functional and reproducible simulator was obtained, consisting of a knee model and an arthroscopic camera. The simulator works adequately adapted to a TV, monitor or computer, and allows the simulation of diagnostic procedures, meniscectomy and meniscoplasty. Conclusion: It is possible to develop a knee arthroscopy simulator, with components available in local and electronic commerce, at a cost of approximately R$ 300.

Effect of Cement Type and Cementation Technique on the Retention of Implant-Supported Restorations.

This study aimed to assess the effect of cement type and cementation technique on the retention of cement-retained implant-supported restorations. In this in vitro study, 20 solid abutments were screwed onto the fixture analogs and were mounted in acrylic resin molds using a surveyor. Twenty computer-aided design/computer-aided manufacturing (CAD/CAM) metal crowns with an occlusal loop were fabricated, divided into two groups (n = 10), and bonded with temporary dental cement (Temp-Bond™; group 1) or glass ionomer (GC; group 2). Each group was subcategorized based on its cementation method (half-filling or abutment replica technique). The cement was applied to the copings that were placed vertically on the abutment with applying a 5-kg load for 10 min. The samples were then incubated at 37°C for 24 h and subjected to 3000 thermal cycles. The samples underwent axial tensile load within a universal testing machine. Data were analyzed using two-way ANOVA. GC cement yielded significantly higher retention than Temp-Bond™ (P < 0.05). In the GC group, the half-filling subgroup showed significantly higher retention than the abutment replica subgroup (P < 0.05). The mean retention value in the Temp-Bond™ group revealed no significant difference between the two subgroups (P > 0.05). GC yielded higher retention than Temp-Bond™ while using the half-filling cementation technique (P = 0.00). However, this difference was not significant between GC and Temp-Bond™ with the abutment replica technique (P = 0.960). Within the limitations of this study, the results showed that permanent cementation with half-filling technique yielded significantly higher retention in implant restorations.

Nanoleakage of different composite restoration systems

ObjectiveThis study was carried out to investigate the nanoleakage of different composite restoration systems (composite materials and its recommended adhesives).Patients and methodsThirty intact, noncarious human premolars were selected. Root apices of all teeth were sealed with wax. For each tooth, the roots were inserted into self-curing resin mold, with the long axis perpendicular to the acrylic resin base. Standardized class V cavities were prepared above the cemento-enamel junction by 1 mm, on the buccal surfaces of the teeth. The prepared teeth were divided randomly into three equal groups (10 each) according to restorative systems used: group 1: nanohybrid composite system, group 2: bulk-fill composite system, and group 3: flowable composite system. Each group was equally divided into two subgroups (five each) according to the thermal and load cycling treatments (A and B). All specimens were examined at the occlusal margins and cervical margins (divisions 1 and 2). All specimens were coated with two layers of nail varnish except for 1 mm, around the restoration margins and immersed in a 50% (w/v), sectioned in bucco-lingual direction and processed for scanning electron microscopy and energy dispersive analysis radiograph.ResultsThe bulk-fill composite system (group 2) recorded the higher silver weight percentage mean value followed by nanohybrid composite system (group 1) while the flowable composite system (group 3) recorded the lowest silver weight percentage mean value in both cases whether the restorations were thermal and load cycled or not. However, a statistically significant difference was recorded in the three tested groups when subgroup A was compared to subgroup B in each group. Moreover, the results indicated that the mean value of nanoleakage at the cervical margins (division 2) in all groups (1, 2, and 3) and subgroups (A and B) recorded a higher significant nanoleakage than the occlusal margins (division 1) except group 2B which recorded no significant difference with a P value of 0.147.ConclusionThe flowable composite system recorded the lowest silver weight percentage mean values. Thermal and mechanical stresses increase nanoleakage significantly.

Rapid injection moulding process of polyether ether ketone based on stereolithography

In this study, photosensitive resin mould was made by stereolithography technology to inject individualized polyether ether ketone (PEEK) parts. In simulation experiment, the temperature field of the PEEK injection mould was analysed by finite element analysis; it was preliminarily determined that the resin mould will not be deformed during the injection process. The optimum parameters of PEEK injection process were obtained by orthogonal experiment: injection temperature 373 °C, injection pressure 11 MPa and injection speed 70%. Mechanical tests were carried out on PEEK samples injected by this process. The results showed that the average tensile strength was 96.4 ± 2.28 MPa, the average bending strength was 147.654 ± 9.36 MPa, and the impact strength was higher than 10 kJ/m2. The experimental results show that it is feasible to produce photosensitive resin mould to inject individualized PEEK parts by stereolithography. Photosensitive resin mould has lower cost, shorter production cycle and no waste of PEEK material during injection process. The injection method in this study greatly reduced the production cost of individualized PEEK parts and can obtain PEEK parts with good mechanical properties in a relatively fast time.

Prospects for automotive SiP modules applying IC assembly and packaging technology

Abstract We develop a package that ensures quality complying with AEC-Q 100 Grade 2 which is in-vehicle quality from various flip chip mounting methods and bump sealing technology with underfill resin and mold resin. FC CSP with heat spreader mounted on the product which has started mass production since last year is in the lineup, The heat dissipation can be improved by attaching the heat spreader directly to the chip backside which are heat sources and the Thermal Interface Material (TIM), using our assembly technology of flip chip mounting and molding the periphery while exposing the chip backside. By adjusting the Coefficient of Thermal Expansion (CTE) and thickness of the material, we realize low warpage and low coplanarity at reflow temperature and product use temperature environment and reduce package displacement behavior, we will improve the secondary mountability to the motherboard and provide reliable packages. Furthermore, it can be applied to SiP modules. It is also possible to construct multiple chip modules by mounting multiple ICs or placing low-passive components around them. We will consider heat spreader mounting on multiple ICs that generate heat, and metal coating on the entire SiP module to have a structure that achieves both heat dissipation and electromagnetic shielding as a future idea.

Computational modeling of resin infusion process applied to small vessel hulls

Polymeric composite materials are largely used for small vessels hull fabrication. They have many desired advantages like low weight, good mechanical performance and good resistance to marine environments. Resin infusion is one of the most common manufacture processes used for this kind of application. In this process, injection tubes are positioned above reinforced media inside mold cavity and resin is forced to flow, first, through these tubes. Tube correct positioning is crucial for a fast and free of imperfections (air bubbles or other filling problems) hull fabrication; however, usually, it is not easy to determine best location for them. In this work, a numerical modeling of the resin injection into a small hull vessel was performed using OpenFOAM software. Besides main solver, other three applications were used in current work. Blender was used to build the tree-dimensional hull geometry, Gmsh used to discretize the geometry, creating a regular mesh formed with hexahedra elements and ParaView used in results post-processing. Finite volume formulation combined with the volume of fluid method was used to solve the multi-phase (air + resin) fluid flow. Four sequential simulations were necessary to determine optimized injection procedure. Each simulation represents an enhancement to the previous one correcting problems like void formation. At the end, some theoretical recommendations are proposed and discussed for an optimized injection procedure for small vessels fabrication.

Bonding of Mold Resin to Copper Substrate through an Amorphous Interlayer Film

Bonding of Mold Resin to Copper Substrate through an Amorphous Interlayer Film

Simulation of dynamic mold compression and resin flow for force-controlled compression resin transfer molding

Abstract In the present study, an improved consolidation model, with mold inertia included, is proposed to completely predict how the upper mold rapidly moves from rest to maximal velocity and then decelerates to a steady value for a constant force-controlled compression resin transfer molding (CRTM). Simulation results show that all preform compaction cases cannot apply to quasi-static consolidation theory in CRTM. For cases with a massy mold, inadequate preform resistance, and low resin viscosity, the mold inertia has a short, remarkable influence on the resin counter-force and causes a slightly slow resin progression in the early compression stage. Contrarily, the compaction of the rigid preform is applicable to the quasi-static consolidation theory. Additionally, a reasonable time increment is discussed for using the quasi steady-state approximation.

Shrinkage Effect of Vacuum Casting Process Parameters using Taguchi Method

This paper investigates the optimization of vacuum casting process by using Taguchi method. Vacuum casting process is a one of the method in Rapid Tooling Technology. The parts produced by vacuum casting process has it accuracy varies with the changes of the process parameters of the machine such as resin temperature, vacuum pressure time, mould temperature and some others. In order to optimize 3 parameters which are resin temperature, mould temperature and vacuum pressure time, the L’9 orthogonal array was used. From the results, it shows that the optimum parameters that may improve the shrinkage effect are resin temperature (30 °C), mould temperature (60 °C) and vacuum pressure time (5 min.). The shrinkage values between default and optimum parameter are 0.159mm and 0.336mm respectively. Thus, the improvement on shrinkage effect was 52.4 percent. The study demonstrates that the better dimensional accuracy of vacuum casting process can be optimized using Taguchi Method.

Multi-material additive manufacturing of polymers and metals using fused filament fabrication and electroforming

This paper proposes an additive manufacturing method that combines fused filament fabrication (FFF) 3D printing and an electroforming technology to fabricate multi-material structures composed of resin and metal. In this method, an FFF 3D printer prints a resin mold that functions as a structural unit in a multi-material structure and as a sacrificial plastic mold for the addition of the metal material. This sacrificial mold is eventually removed. Electroforming the interior of a printed resin mold enables the fabrication of multi-material structures using resin and metal materials. The fabrication conditions for multi-material structures when using the proposed method were investigated and the surfaces of the resulting structures were evaluated. The fabrication conditions for the specified thickness per process and the total thicknesses from all the processes were determined. Furthermore, our results indicated that the shape of the side of the metal portion depended on the forming precision of the FFF 3D printer. We present an example of the fabrication of a gear shape from resin and metal.

Optimization method to select temperature based on chemorheological and exothermal reaction of RTM

ABSTRACTHeating mold and resin have been widely used in resin transfer molding (RTM) to improve injection and manufacturing efficiency. The unreasonable mold/resin temperatures sometimes lead to excessive viscosity of resin and premature curing, which will result in failure of the filling process. Selection of optimal mold and resin temperature has become a source of concern in the polymer industry. This article presents an optimization method to select mold and injection resin temperatures by using numerical simulation based on chemorheological and exothermal reaction of the RTM process. The results show that the optimization method has high computational efficiency for three‐dimensional parts with different shapes. The selected mold/resin temperature ensures the smooth filling process, which provides a powerful tool for parameter design in polymer industry. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48245.

Ultrasonic beam induced resistance change (SOBIRCH) method for failure analysis of semiconductor devices encapsulated by mold resin

In the process of the failure analysis for semiconductor devices, various optical methods are applied as techniques to localize faults of the semiconductor devices. Conventional optical techniques often require the decapsulation of the mold resin, since the mold resin is not optically transparent. As a new fault localization technique requiring no decapsulation, the authors are proposing the ultrasonic beam induced resistance change (SOBIRCH) method based on a heating by focused ultrasonic beam. In this report, the signal intensity of the SOBIRCH method for the capsulated samples was discussed through the experimental and the theoretical approaches. By comparing the experiment and the numerical analysis, it was suggested that a certain thickness of the thin mold resin can enhance the intensity of the SOBIRCH signal. Additionally, an expected effect of the standing wave in the thin mold resin was calculated, and a method to make use of the standing wave was proposed.

Influence of Aging on Phenolic Resin Molding Materials

Influence of Aging on Phenolic Resin Molding Materials

Development of an Injection Mold for Liquid Silicone Rubber Using Rapid Tooling Technology

ABSTRACTRapid tooling (RT) technology can reduce the time to market for injection molded products compared to standard machining methods. Aluminum-filled epoxy resin molds can be used in place of conventional steel molds for small batch injection molding production. Liquid silicone rubber (LSR) parts are stable and used in many applications. To compress time to market for new injection molded products it is necessary to develop a mold swiftly and effectively. In this study, RT technology was used to make a mold with a heating element for LSR injection molding. The mold was fabricated from aluminum-filled epoxy resin and injection could be done after a mold warm-up time of 35 min – to stabilize mold surface temperature. The optimal process parameters were found to be: injection speed 50 mm/s, packing pressure 14 MPa, mold temperature 180°C, and packing time 12 s.

Epoxy resin mold and PDMS microfluidic devices through photopolymer flexographic printing plate

Photopolymer flexographic printing plate is a new photopolymeric material used for microdevices fabrication. This work demonstrates that a photopolymer flexographic master mold can be used for the fabrication of PDMS (polydimethylsiloxane) microdevices by a multi-step manufacturing process. The methodology entails three main fabrication steps: (1) a photopolymer flexographic printing plate mold (FMold) is generated by UV exposure through a transparent film, (2) an epoxy resin mold (ERmold) is fabricated by transferring the features of the photopolymer mold and (3) a PDMS microdevice is manufactured from the epoxy resin mold. The characterization of the manufactured PDMS microdevices was performed using scanning electron microscopy (SEM) and profilometry. Results showed high accuracy in the replication of the profiles. To show the feasibility of the fabrication process a microdevice for microdroplet generation was designed, manufactured and tested. Hence, the manufacturing process described in this work provides an easy, robust, and low-cost strategy that facilitates the scaling-up of microfluidic devices without requiring any sophisticated equipment.

Effect of Commercially Available Denture Adhesives on Microhardness of a Flexible Denture Base Material.

BACKGROUND:Various clinical cases of thermopress denture base materials necessitate the use of denture adhesives to achieve proper retention and stability of the removable prosthesis. Therefore; the microhardness of these flexible materials as surface property and its’ alterations due to the application of various denture adhesives are still crucial issues to be discussed.AIM:This study aimed to investigate the impact of two commercially available denture adhesives (DAs) on microhardness of a flexible denture base material.METHODS:A total of 30 duplicate disc specimens (DS) were fabricated from a thermoplastic injection moulded resin (TR). The obtained 30-disc specimens (DS) were stored in distilled water for seven days, and then their microhardness was measured using Knoop Hardness Test (KHN) under a 10 g load for 10 seconds. The denture adhesives were prepared, and 15 DS were immersed in Corega Super Cream, while the other 15 DS were soaked in Fitty Dent Cream. All DS were stored in distilled water at 37°C. After 30 days of immersion in DAs, microhardness of DS was again measured. T-test for paired observation was used to investigate any alterations in microhardness between the baseline and after 30 days of immersion in the DAs. Statistical analysis was performed with SPSS 20®, Graph Pad Prism® and Microsoft Excel 2016 with a significant level set at P ≤ 0.05.RESULTS:Student`s t-test had revealed a significant difference between both groups after application of denture adhesive as a P value < 0.05. The obtained results showed that DA material type, flexible denture base material and their surface interaction provoke a statistically significant outcome on the mean microhardness.CONCLUSIONS:DAs were found to affect the microhardness of thermoplastic injection moulded resin (TR); which may jeopardise the durability and serviceability of complete denture and patients’ acceptance and comfortability.

PROCESSING ADDITIVES AND RHEOLOGICAL PROPERTIES OF MOLDED PHENOLIC PLASTICS

By the method of capillary viscosimetry, the melt flow curves of the molded phenolic resin and its compositions with lubricant, plasticizer and their mixture were obtained. It was shown that the size (diameter) of the capillary channel influences the dependence of the effective shear rate on the shear stress (flow curves) of the studied compositions. Such rheological behavior of the compositions during flow is associated with the effect of sliding along the surface of the capillary wall. According to the Mooney method, the dependences of the effective shear rate at given values of shear stress on the reciprocal of the capillary radius are plotted. The function of the slip velocity on the shear stress on the capillary wall is characterized in terms of the slip coefficient, which relates the shear stress on the capillary wall to the velocity of the composition along it. For the studied compositions, the total flow through the capillary was divided into volume fractions, one of which is associated with a shear flow; the other is determined by the slip effect. It has been shown that the introduction of both a lubricant and a plasticizer into the composition leads to an increase in the fluidity of the compositions. At the same time, adding of lubricant increases the volume fraction of the slip flow. The greatest effect of increasing the fluidity of the composition gives the use of complex modifying additives containing both lubricant and plasticizer.

Modeling and 3D Simulation of the Mould Compression and Resin Flow for Force-Controlled Compression Resin Transfer Moulding

Since the existence of the complicated coupling between mould compression and resin flow, the full 3D simulation of the filling process in force-controlled compression resin transfer moulding (CRTM) has not been realized, especially when the resin flow front is irregular on the thickness direction during thick part moulding. In this paper, the coupled resin flow and mould compression behaviors are investigated firstly, a equivalent spring method is proposed to describe the preform compaction. The lubrication effect is taken into account, so the mould compression speed can be determined when the resin flow front is irregular on the thickness direction. Then the Volume of Fluid (VOF) two-phase model is established to express the resin-air flow in narrow gap and preform simultaneously, in which the narrow gap is considered as 3D area without flow resistance. Finally, the 3D numerical method for solving the above mathematical models is developed. In this method, the changing of the mould cavity is simulated by moving mesh technology, and the master-slave element method is used to simulate the resin squeezing from the infiltrated preform. Comparisons with analysis results are provided to prove the correctness of the above method, and two 3D examples are given to demonstrate the simulating capability.

Modeling and 3D Simulation of the Mould Compression and Resin Flow for Force-Controlled Compression Resin Transfer Moulding

Modeling and 3D Simulation of the Mould Compression and Resin Flow for Force-Controlled Compression Resin Transfer Moulding

Nonisothermal simulation on pressure during resin transfer molding

ABSTRACTHigh speed injection has been widely used in resin transfer molding (RTM), which improves manufacturing efficiency. This sometimes leads to excessive pressure within the mold, resulting in fiber destruction and mold deformation. Heating the mold and injection resin reduces the viscosity of resin, leading to influence on mold internal pressure. Selection of optimal mold and injection temperature for effective reduction of mold internal pressure has become a source of concern in the polymer industry. This article presents an outlook relationship between mold temperature, injection temperature, and mold internal pressure. It also showcases a temperature selection method angle to addressing this issue. The “FLUENT” software has been secondarily developed that gives an insight in using the three‐dimensional nonisothermal RTM simulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47492.