Rubber Mold Research Articles

MATERIAL RESPONSE OF RAMAX-2 DURING HIGH-SPEED MACHINING USING QUICK-STOP DEVICE

Ramax-2 is chromium-alloyed stainless holder steel. It is manufactured by Uddeholm Tooling AB (Hagfors, Sweden) and supplied in prehardened and tempered condition. It is used for plastic and rubber molds and for dies for plastic extrusion. It has excellent machinability and corrosion resistance and has uniform hardness comparable with AISI 420F. It was machined by turning process and the formation of shear bands and their width was observed in the chips collected at cutting speeds from 50 to 250 m/min. The chemical composition of the workpiece material is given in Table 1. The mechanical and physical properties are given in Table 2. The samples were taken from a round bar of 28 mm diameter. The purpose of this research was to experimentally measure the response of Ramax-2 at cutting speeds ranging from 50 to 250 m/min, the upper limit being in the domain of high-speed machining. Shear band formation at various strain rates will be measured, and consequently, the strain rates generated in high-speed machining of Ramax-2 will be calculated.

Effect of rubber hardness on the properties of fiber reinforced plastic composites made by the newly proposed rubber pressure molding technique

AbstractThe effect of rubber hardness on the properties of fiber‐reinforced plastic (FRP) composites is investigated in order to know the optimum composition of rubber mold used in rubber pressure molding (RPM) technique. A matching die set was used in RPM method, where the die was made of hard metal like steel and the punch from the flexible rubber like material, natural rubber. The use of flexible rubber punch generates and applies hydrostatic pressure on the surface of FRP composites. The hardness of rubber mold was controlled by incorporating carbon black as a filler material in the matrix of natural rubber and varied from 0 to 75 phr (per hundred rubber) in steps of 15 phr. Burn test, tension test, interlaminar shear test and interlaminar fracture toughness tests were conducted on the FRP composites to measure the void content, presence of delamination, tensile strength, inter laminar shear strength and inter laminar fracture toughness. The results are compared with the FRP composites made by conventional technique to evaluate the performance of RPM technique. It is observed that the laminates produced by RPM technique with different filler content in natural rubber mold show significant improvement in mechanical properties except interlaminar shear strength. POLYM. COMPOS., 28:618–630, 2007. © 2007 Society of Plastics Engineers

Analysis of rubber pressure molding technique to fabricate fiber reinforced plastic components

AbstractA rubber pressure molding technique is developed to prepare fiber reinforced plastic components having complex shaped geometry. The technique is based on the matching die set, where the die is made of hard metal like steel and the punch from flexible rubber like materials. The use of flexible rubber punch helps to intensify and uniformly redistribute pressure (both operating pressure and developed hydrostatic pressure due to the flexible rubber punch) over the surface of product. The distribution of pressure was analyzed by ANSYS over a processing pressure of 0.5 to 50 MPa. The analysis was extended to find out the optimum hardness of rubber mold, where the pressure distribution is uniform. For this, analysis was carried out for NR vulcanizates where the loading of carbon black was varied from 0 to 75 phr, with an increment of 15 phr using the strain energy density function of two‐, three‐, five‐, and nine‐parameter Mooney–Rivlin, first‐, second‐, and third‐order Ogden, Neo–Hookean, first‐, second‐, and third‐order Polynomial, Arruda–Boyce, first‐, second‐, and third‐order Yeoh and Gent. 45 phr carbon black loading in NR vulcanizate shows best result. POLYM. COMPOS., 28:637–649, 2007. © 2007 Society of Plastics Engineers

Effects of temperature on interlaminar fracture toughness of fibre reinforced plastic composites made by newly proposed rubber pressure moulding technique

The present paper has investigated the effect of temperatures (i.e.−70–100°C) on the interlaminar fracture toughness (ILFT) of fibre reinforced plastic (FRP) composite panels made by a recently developed process known as the rubber pressure moulding (RPM) technique. The RPM technique is based on the matching die set, where the die is made of hard metal like steel and the punch from flexible rubber like materials. The use of flexible rubber punch helps to intensify and uniformly redistribute pressure (both operating pressure and developed hydrostatic pressure due to the flexible rubber punch) on the surface of the product. Natural rubber was used to prepare rubber punch in this investigation. For performance evaluation of FRP composites made by the RPM technique, FRP composites were also made by conventional method and tested at the same temperatures. It is observed that Mode I ILFT of FRP composites decreases towards higher and lower extremes of the temperature range selected. FRP composites made by the RPM technique show a higher Mode I ILFT over the 25–100°C temperature range than those made by the conventional process.

Modelo simulador para treinamento de punção transpedicular em vertebroplastia percutânea

OBJETIVO: Desenvolver e testar a similaridade de modelo de coluna lombar tipo manequim para treinamento de punção transpedicular em vertebroplastia percutânea. MATERIAIS E MÉTODOS: Foram confeccionadas 30 vértebras lombares à base, principalmente, de metacrilato, gesso e etil-vinil-acetato, a partir de molde de borracha baseado em vértebra humana. Os discos intervertebrais foram feitos com silicone para que houvesse similaridade anatômica e fusão de cinco vértebras. O segmento da coluna foi acondicionado no interior de um manequim coberto por tela de etil-vinil-acetato para que não fosse possível a visualização direta. Foi realizado curso teórico para seis especializandos de radiologia e neurorradiologia, que testaram o modelo para vários parâmetros de similaridade com a realidade, realizando 30 punções transpediculares, em três sessões de dez procedimentos por dia, com intervalo de uma semana entre cada sessão. RESULTADOS: Cada aluno realizou 30 punções transpediculares, porém oito punções foram desconsideradas, pois se observaram problemas de manufatura dos modelos durante estes procedimentos. Após a realização das punções, todos os participantes preencheram o formulário de similaridade, com 100% de respostas positivas em relação à similaridade do modelo. CONCLUSÃO: Foi possível o desenvolvimento de modelo para punção transpedicular com similaridade satisfatória com o ser humano, configurando um instrumento de treinamento de vertebroplastia.

Manual Application of Controlled Forces to Thoracic and Lumbar Spine With a Device: Rated Comfort for the Receiver's Back and the Applier's Hands

Purpose High volumes of manual therapy work can lead to overuse hand and wrist injuries. This study evaluated hand and back comfort in asymptomatic volunteers during spinal mobilization carried out with an instrumented manual therapy tool. Methods This crossover design study examined 36 asymptomatic physiotherapy students that were tested in pairs. One participant assumed the role of the simulated therapist and the other the simulated patient, before reversing roles. Posteroanterior mobilization conditions formed by using 2 spinal segments (thoracic/lumbar), 2 force application methods (hands/device), and 3 grades of mobilization were applied in a random order. After each combination, both participants in each pair rated hand or back comfort, respectively, on a 100-mm visual analogue scale. Data were analyzed by analysis of variance. Results Rated back comfort was greater for hands than for the device and decreased with greater applied force. When the original hard rubber device tip was changed to one of soft molded rubber, both back and hand comfort improved significantly. Although tool mobilization was still rated as significantly less comfortable than mobilization with hands only, this difference was approximately half the discomfort experienced as the grade of mobilization increased from grade I to grade III. For hand comfort when using the softer device tip, the method of force application was no longer a significant determinant of comfort. Conclusions The mobilizing tool with a molded rubber tip was acceptably comfortable in use with asymptomatic backs and hands. Further research is indicated in manual therapy settings with therapists who have experienced hand pain.

Pressure distribution analysis of fiber reinforced plastic components made by rubber pressure moulding technique

AbstractFiber reinforced plastic component (FRP) having complex shaped geometry is prepared by rubber pressure molding (RPM) technique. The technique is based on the matching die set, where the die is made of hard metal like steel and the punch from flexible rubber like materials. The flexible rubber punch intensifies and uniformly redistributes pressure (both operating pressure and developed hydrostatic pressure due to the flexible rubber punch) over the surface of product. The distribution of pressure was analyzed by ANSYS over a processing pressure of 0.5–50 MPa. The analysis was extended to find out the optimum hardness of rubber mold, where the pressure distribution is uniform. For this, analysis was carried out for NR vulcanizates where the loading of carbon black was varied from 0 to 75 phr with an increment of 15 phr. The strain energy density function of 2‐, 3‐, 5‐ and 9 parameter Mooney‐Rivlin; 1st‐, 2nd‐, and 3rd order Ogden; Neo‐Hookean; 1st‐, 2nd‐, and 3rd order Polynomial; Arruda‐Boyce; 1st‐, 2nd‐, and 3rd order Yeoh; and Gent were used. 45phr carbon black loading NR vulcanizate shows best result. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Possibilities and constraints of implementing starch consolidated high speed steel in prototyping

In the starch consolidation (SC) process, a water-based slurry containing powder, starch, dispersant and thickener is used to fabricate near net-shape green bodies that are de-binded and further consolidated by sintering. In this study, gas atomized M3/2 as well as high and low carbon V-rich M4 type high speed steel powder (<150 μm) are considered. Both material types undergo high volumetric shrinkage during super-solidus liquid phase sintering enabling them to reach near full density. The analyses and the review cover different process aspects like: recipe optimisation, post-gelatinization drying, de-binding and sintering. A SC recipe consisting of 58 vol.% powder, 3 vol.% starch, 1 vol.% dispersant and a thickener solution resulted in a density of >98% than what is theoretically stated after sintering. It is found that the success of the post-gelatinization drying procedure depends on the smoothness of mould material and controlling powder oxidation. The best combination was freeze drying the slurry in a silicon rubber mould. For V-rich alloys a total or partial control of eutectic carbides in the final microstructure could be realized for vacuum and nitrogen sintering atmospheres, respectively.

Micro-mould fabrication for a micro-gear via vacuum casting

A micro-mould fabrication method based on vacuum casting was developed and its functionality and reproducibility were demonstrated. The micro-components used in this study were SU-8 photoresist micro-gears fabricated by UV photolithography. These micro-gears served as the master patterns from which silicone rubber micro-mould cavities were fabricated with the use of the vacuum casting technology. The process parameters that had an influence on the quality of the micro-mould cavities were identified and optimised. Using the optimised process parameters resulted in high fidelity silicone rubber micro-mould cavities at high resolutions. Dimensional analysis was carried out using white light interferometry. It was found that all the micro-gear cavities in the micro-moulds were dimensionally accurate and consistent to the master gear, with a dimension deviation less than 3% of the respective dimensions. Micro-casting was also carried out using the silicone rubber moulds. Micro-gears were successfully transferred from the silicone rubber moulds into PU resin and wax pieces under vacuum conditions, thereby demonstrating that the micro-mould fabricated was capable of producing functional micro-parts that were able to replicate micro-features.

Dimensional accuracy analysis of wax patterns created by RTV silicone rubber molding using the Taguchi approach

PurposeDimensional accuracy analysis of wax model created by room temperature vulcanization (RTV) silicone rubber molding to be used in investment casting is presented. The purpose of this paper is to discuss the effective parameters of dimensional accuracy in RTV tooling technique.Design/methodology/approachAfter producing a pattern by stereolithography (SLA) and then creating the RTV silicone rubber mold by the SLA pattern, dimensional accuracy of wax models produced by RTV tool are analyzed. Design of experiments (DOE) using the Taguchi approach is used for analysis and determination of optimum condition.FindingsExperiments show that the dimensional accuracy in RTV technique is as accurate as in traditional molding. Hence, RTV tooling technique can be used in investment casting. Using Taguchi approach based on DOE, it was realized that the optimum condition to achieve acceptable accuracy is 35°C for mold temperature, 85°C for wax temperature, and −0.5 barG for vacuum pressure.Practical implicationsRTV silicone rubber mold is a useful alternative of metallic mold to produce wax patterns for investment casting. It has benefits such as reduction in production lead‐time and cost, compared with traditional metallic mold.Originality/valueA case study for research of dimensional accuracy of wax patterns created by RTV silicone rubber mold had not been attempted as such. In addition to reduction in production lead‐time and cost, the dimensional accuracy of wax patterns using RTV tooling technique are as accurate as in traditional technique.

Use of rapid prototyping models in the planning of percutaneous pulmonary valved stent implantation

Percutaneous replacement of the pulmonary valve is a recently developed interventional technique which involves the implantation of a valved stent in the pulmonary trunk. It relies upon careful consideration of patient anatomy for both stent design and detailed procedure planning. Medical imaging data in the form of two-dimensional scans and three-dimensional interactive graphics offer only limited support for these tasks. The paper reports the results of an experimental investigation on the use of arterial models built by rapid prototyping techniques. An analysis of clinical needs has helped to specify proper requirements for such model properties as cost, strength, accuracy, elastic compliance, and optical transparency. Two different process chains, based on the fused deposition modelling technique and on the vacuum casting of thermoset resins in rubber moulds, have been tested for prototype fabrication. The use of anatomical models has allowed the cardiologist's confidence in patient selection, prosthesis fabrication, and final implantation to be significantly improved.

Trelleborg acquires Swedish rubber moulding company

Through its Trelleborg Engineered Systems business area, Trelleborg has signed an agreement to acquire Swedish company Gummiteknik GTM AB, with approximately 30 employees and annual sales of about SEK36 million (US$5.2 million).

Deformation and energy absorption of composite egg-box panels

Static compressive tests of composite egg-box panels, whose stacking sequences and number of plies were controlled, were carried out to investigate their deformation behaviour and energy absorption capacity. Silicon rubber moulds were first moulded from an aluminium egg-box panel template. These moulds were in turn used to fabricate composite specimens. Two fabric prepregs, carbon/epoxy plain weave fabric and glass/epoxy 4-harness satin weave were draped over the rubber mould with various stacking angles. The specimens were cured in an autoclave using vacuum bag degassing moulding and an appropriate cure cycle. The nominal stress–strain relations of the specimens were compared and multiply-interrupted compressive tests were used to identify fracture initiation and development. The energy absorption per unit mass of composite egg-box panels were compared with that of an aluminium egg-box panel. From the test results it was concluded that the compressive behaviour of the composite structure is affected by the local stacking sequence of the fabrics and by shear deformation during initial lay-up and draping. By considering the stress–stain behaviour, energy absorption and material cost, the optimal material and draping condition were proposed for a composite egg-box panel.

ゴム・エラストマーの技術動向と将来

This review describes the technical trends of rubber and elastomer such as rubber materials, nano-composites of clay, carbon nanotube, adhesion of rubber/metal, rubber mold, mold pollution, analytical estimation of rubber/filler, recycle of waste, new production system of tire, etc., and rubber technologies in the future.

Effect of light-curing methods on resin cement knoop hardness at different depths

This study evaluated, using Knoop hardness test, the polymerization depth of Rely-X dual-cured resin cement activated by chemical reaction alone (control group) or by chemical/physical mode with light curing through a 1.5-mm-thick ceramic layer (HeraCeram). Bovine incisors had their buccal surface flattened and hybridized. On this surface, a rubber mould (5 mm diameter; 1 mm high) was bulk filled with cement. Either a polyester strip or a 1.5-mm-thick disc of the veneering material was seated over this set. Light curing was performed with either conventional halogen light (QTH; XL2500) for 40 s, light-emitting diode (LED; Ultrablue Is) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. In a control group, cement setting occurred by chemical reaction alone. After storage dry in dark (24 h/37 degrees C), the specimens (n=5) were sectioned for hardness (KHN) measurements at three depths in a microhardness tester (50 gf load/15 s). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). Rely-X cement presented higher Knoop hardness values when the QTH and LED LCUs were used, compared to the control group and PAC. Light curing with PAC resulted in lower hardness compared to the control group. Cement hardness was significantly lower in deeper regions.

Preparation of Er-Doped Glass by a Compression-Forming Method

Erbium-doped silica-based glass for optical amplifiers is fabricated from silica powders by a compression-forming method using a cold isostatic pressing (CIP) technique. Silica powders are prepared from slurry containing fumed silica with submicrometer diameter and erbium source by granulating using a spray drier. The average diameter of the granulated powders is 50 μ and about 150 times as large as that of the fumed silica. The silica powders are packed in a rubber mold and are compressed by CIP. It is found from thermal analysis that the compressed powders can be degreased PVP at 600°C. After degreasing at 600°C, the compressed powders are sintered by a sintering process using an electric furnace or a gas burner. The compressed powders can be vitrified by using not the electric furnace but the gas burner. The existence of Er ions in the glass sintered by the gas burner is confirmed from UV-VIS spectra.

Fabrication of high-resolution periodical structure on polymer waveguides using a replication process

This paper describes a procedure to replicate a polymeric wavelength filter. In this work, the grating structure on a polymer is fabricated first using holographic interferometry and micro-molding processes. The polymeric wavelength filters are produced by a two-step molding process where the master mold is first formed on a negative tone photoresist and subsequently transferred to a PDMS mold; following this step, the PDMS silicon rubber mold was used as a stamp to transfer the pattern of the polymeric wavelength filters onto a UV cure epoxy. Initial results show good pattern transfer in physical shape. At the Bragg wavelength, a transmission dip of -15.5 dB relative to the -3dB background insertion loss and a 3-dB-transmission bandwidth of ?6nm were obtained from the device.

Recent Advances in Dry-Bag Cip Equipment

Dry-bag CIP process has become a very popular method in the large volume production of powder compacts in the P/M and ceramic industries. Intensive technological research on the Drybag equipment has been carried out to improve the dimensional accuracy and the productivity. In this study, the rubber mold design technology with FEM simulation during pressing has been introduced, in order to achieve higher dimensional preciseness, and criteria for the selection of Drybag equipment, namely the In-line type or Off-line type, have been established based on the powder flowability index proposed by Carr. Based on these research results, high productivity Off-line Drybag CIP equipment, which can realize good dimensional accuracy with high productivity, was developed even for non granulated powders with poor packing density. This paper describes the research results and the present status of the most advanced Off-line Dry-bag CIP equipment technologies.

Fabrication of polymer waveguides by a replication method

We have developed a soft-lithography method to replicate polymer waveguides. In this method, the waveguides are produced by a two-step molding process where a master mold is first formed on a negative-tone photoresist and subsequently transferred to a polydimethylsiloxane (PDMS) mold; a PDMS silicone rubber mold is then used as a stamp to transfer the final waveguide pattern onto an UV cure epoxy. Initial results show good pattern transferring in physical shape. The optical performance is measured based on the propagation loss. In our design, the loss was measured at 0.28 dB/cm for 1.3 microm and 0.26 dB/cm for 1.55 microm.

Effect of preheat temperature on the location of the minimum state of cure in a molded component

AbstractThe distribution of state of cure in a molded rubber component is usually nonuniform due to the slow heat transfer processes involved in the molding–cooling cycle. The minimum in the distribution usually occurs in the center of the rubber section. For large components, one method of reducing molding time is to preheat the uncured rubber prior to molding, thus carrying out a portion of the required heat transfer in a more favorable geometry than the molded shape. In this work, computation of the state of cure distribution in preheat–molding–cooling cycles for one‐dimensional rectangular geometry shows that as the preheat temperature is increased, the locus of the minimum state of cure will move outward from the center toward the surface of the component. This has important implications for the range of cure states existing in an article and calls into question the convention of removing samples for state of cure tests from the center of the component. The variables considered in this work are the preheat temperature, the component thickness, and the target state of cure of the rubber compound. A design curve is developed whereby the preheat temperature to optimize the distribution of the cure can be established. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25:195–207, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20070