Conventional Mold Research Articles

Comparison of Properties of Carbon Fiber Reinforced Thermoplastic and Thermosetting Composites for Aerospace Applications

In the present study the properties of carbon fiber reinforced poly ether ketone (PEK) is compared with carbon fiber reinforced epoxy (EP) composite fabricated by compression moulding technique. PEK carbon fiber (PK-CF) composites are prepared by film stacking method whereas the epoxy carbon fiber (EP-CF) composites are prepared by conventional compression moulding route maintaining a constant 60wt% carbon fiber. The tensile properties analysis indicated that PK-CF composite possesses a tensile strength of 425MPa which was much higher than 311MPa recorded by EP-CF. The stress intensity factor (K IC ) values of PK-CF composites are found to be 10% higher than EP-CF counterparts. It is seen that the PK-CF composites possess higher glass transition temperature enabling them to be used at elevated temperatures. The investigation of flame retardant behaviour of the composite is conducted by Limiting Oxygen Index (LOI) test, and highest value is obtained for PK-CF composite.

Studies on Selected Mechanized Solutions for Efficient Incorporation of Green Manure Crop

A comparative study on incorporation of green manure crop (Sesbania aculeata) with a newly developed tractor operated biomass incorporator (BI) was conducted in contrast to prevailing technologies. Average depth of soil cut with BI (174.7 mm) was significantly higher than rotavator (71.3 mm), disc harrow (114 mm) and disc harrow plus cultivator (121 mm) at crop growth stage I (36 DAS) and stage II (50 DAS). Size of cut with BI (202 mm and 326.5 mm) was significantly lower than disc harrow, disc harrow pluscultivator and mould board plough at crop growth stage I and II. Field capacity of BI and conventional mould board plough was significantly lower than rotavator and disc harrow because of smaller width of coverage of two-bottom implements. Fuel consumption was significantly higher for rotavator at both stages of crop growth. Pulverization index was lowest with rotavator (6.70 mm and 6.98 mm), followed by BI, disc harrow plus cultivator, disc harrow and mould board plough at both crop stages. Bulk density index was significantly high for BI, followed by rotavator, mould board plough, disc harrow plus cultivator and disc harrow at both crop stages. Mixing index with BI (97.1 %) was significantly higher than all other implements. Biomass incorporator resulted in analogous mixing index at both crop stages. For all other implements, decrease in mixing index was recorded.

Studies on Selected Mechanized Solutions for Efficient Incorporation of Green Manure Crop

A comparative study on incorporation of green manure crop (Sesbania aculeata) with a newly developed tractor operated biomass incorporator (BI) was conducted in contrast to prevailing technologies. Average depth of soil cut with BI (174.7 mm) was significantly higher than rotavator (71.3 mm), disc harrow (114 mm) and disc harrow plus cultivator (121 mm) at crop growth stage I (36 DAS) and stage II (50 DAS). Size of cut with BI (202 mm and 326.5 mm) was significantly lower than disc harrow, disc harrow pluscultivator and mould board plough at crop growth stage I and II. Field capacity of BI and conventional mould board plough was significantly lower than rotavator and disc harrow because of smaller width of coverage of two-bottom implements. Fuel consumption was significantly higher for rotavator at both stages of crop growth. Pulverization index was lowest with rotavator (6.70 mm and 6.98 mm), followed by BI, disc harrow plus cultivator, disc harrow and mould board plough at both crop stages. Bulk density index was significantly high for BI, followed by rotavator, mould board plough, disc harrow plus cultivator and disc harrow at both crop stages. Mixing index with BI (97.1 %) was significantly higher than all other implements. Biomass incorporator resulted in analogous mixing index at both crop stages. For all other implements, decrease in mixing index was recorded.

In Continuing Search of Alternative Accounts: Breaking the Conventional Mold of International Studies

In Continuing Search of Alternative Accounts: Breaking the Conventional Mold of International Studies

Effect of cellulosic filler loading on mechanical and thermal properties of date palm seed/vinyl ester composites

There are numerous better applications of fibre reinforced polymer composites today, when compared with metals and alloys. Many studies have been conducted to further improve the inherent mechanical and thermal properties of the composite materials, especially with sustainable, environmental friendly, recyclable and biodegradable reinforcements. Consequently, in this current study, the composites were prepared by combining bio solid waste (date seed filler) and vinyl ester to enhance the properties of polymer composites. The date seed filler reinforced vinyl ester (DSF-VE) composites were prepared by using conventional compression moulding technique with varying fillers loadings from 5% to 50%. The mechanical (tensile, flexural, impact and hardness), water absorption and thermal (heat deflection temperature and thermo-gravimetric analysis) properties of the DSF-VE composites were experimentally evaluated. Scanning electron microscopic analysis was carried out to analyse the surface characteristics and fractured surface of the DSF-VE composites. It was evident from the results obtained that 30 wt% of the DSF-VE composites exhibited the highest mechanical properties: impact, tensile, hardness and flexural of 17.03 KJ/m2, 40.3 MPa, 51 and 149 MPa, respectively, among the fabricated composites. Similarly, the heat deflection temperatures of DSF-VE composites increased by 58.49%, when compared with the neat, pure vinyl ester resin. The thermo-gravimetric analysis showed that the natural filler-based (DSF-VE) composites possessed thermal stability up to 400.2 °C, which was within the polymerisation process temperature. Furthermore, the DSF-VE composites have been successfully utilized for various potential applications, such as fabrication of a table fan blade, an engine guard for two-wheelers and self-motor guard for four wheelers.

Effect of Bentonite Clay Addition on the Thermal and Mechanical Properties of Conventional Moulding Sands

Effect of Bentonite Clay Addition on the Thermal and Mechanical Properties of Conventional Moulding Sands

A novel route for volume manufacturing of hollow braided composite beam structures

This work investigates the application of a rapid variothermal moulding process for direct processing of a braided thermoplastic commingled yarn. The process uses locally controllable, responsive tooling which provides opportunities for optimum part quality and significantly reduced cycle times compared with conventional processes. The proposed process was used to directly manufacture hollow beam structures from dry commingled braided preforms. It was demonstrated that the cycle time using the rapid process was reduced by more than 90% as compared to a conventional bladder moulding process, resulting in a total cycle time of 14 min. Additionally, initial three point flexure test results indicated an improvement in the mechanical performance of the resultant parts as compared to the benchmark.

Relationship and mechanism between microstructure and property of C70250 copper alloy strip prepared by temperature controlled mold continuous casting

Temperature controlled mold continuous casting (TCMCC) technology was used to fabricate the C70250 copper alloy strips. The influences of solidification microstructure on mechanical and electrical properties of C70250 copper alloys were systematically studied, and the relevant influencing mechanism was discussed. The results show that the microstructure of TCMCC C70250 copper alloy has a large number of fine dispersed Ni2Si phases, small angle grain boundaries and columnar grains with strong [001] orientation. The tensile strength, elongation and electrical conductivity of the C70250 copper alloy are 328 MPa, 40.4% and 24.3% IACS, respectively, which are obviously higher than the properties of the C70250 copper alloys prepared by conventional cold mold casting methods. The tensile strength of TCMCC C70250 copper alloy strip significantly increases due to the dislocation plugging inside the grains, which caused by strong pinning effect of Ni2Si phases during room temperature tensile. Straight small angle grain boundaries and columnar grains with strong [001] orientation significantly reduce the hindering effect of grain boundaries on dislocations. The deformation between and within grains is more uniform, and it is not easy to form high strain concentration, which leads to the increase of plastic deformation ability. The scattering effects of solute atoms and transverse grain boundaries on electrons are significantly reduced due to the precipitated Ni, Si atoms and the high orientation of columnar grain structure, which contributes to the improvement of the electrical conductivity.

Nanoimprinting reflow modified moth-eye structures in chalcogenide glass for enhanced broadband antireflection in the mid-infrared.

We report on the progress towards developing a new method for fabricating more efficient, broadband antireflective (AR) moth-eye structures in As2Se3 via a direct nanoimprinting technique. Thermal reflow is used during mold fabrication to reshape a conventional deep-ultraviolet lithography in order to promote a pattern transfer of "secant ogive"-like moth-eye structures. Once replicated, structures modified by reflow displayed greater AR efficiency compared to structures replicated by a conventional mold, achieving the highest spectrum-averaged transmittance improvement of 12.36% from 3.3 to 12 μm.

Fabrication and characterization of two-phase syntactic foam using vacuum assisted mould filling technique

Conventional mould casting technique for cell foam production demonstrated trapped air bubbles in the cell foam which are undesirable stress concentration points in the matrix. This study devise a modified process technique of fabricating syntactic foam by eliminating interstitial porosity. Varying epoxy hollow spheres and matrix stoichiometry ratio was involved in the fabrication of syntactic foam. Analysis through characterization of the mechanical properties, macrostructural morphology, cell size distribution, wall thickness and curing conditions was determined. The influence of fabrication techniques on performance of the syntactic foams was also evaluated. From the results the hollow sphere size distribution prevented the interstitial spaces, enhanced density and create foam compactness. The matrix stoichiometry ratios impacts the foam morphology, the optimal formulation was 1:1 because it enhances cross-linking within the matrix and produced a smooth, strong surface microsphere coating with structural rigidity. The relative density, compressive modulus and compressive strength of the syntactic foam are 377.11 kg/m3, 556.39 MPa, 10.40 MPa and 334.61 kg/m3, 37.05 MPa, 4.11 MPa, for vacuum assisted mould filling and conventional mould casting method, respectively. Crack propagation test showed failure started at the center and spread through the edges of the syntactic foam because of good interfacial bonding between sphere and matrixes.

Additive manufacturing applied to injection moulding: technical and economic impact

PurposeThe purpose of this study is to compare the overall performance of the injection moulding process by using metallic inserts produced by both conventional technologies and selective laser melting (SLM).Design/methodology/approachA systematic methodology is proposed for prior evaluation of the effectiveness of conformal cooling channels to reduce cycle time and/or to reduce the scrap rate.FindingsThe mould was reengineered considering the SLM process and manufactured. Injection trials were carried out to validate expectations provided by injection simulations, which resulted on good quality parts and a significant decrease on cooling time, and, consequently, on the overall cycle time. The minimisation of scrap provided energy savings and time-to-market reduction.Research limitations/implicationsThe initial costs for AM tools still pose some doubts on decision-makers. The challenge of this study is to implement the methodology on a small-scale production and still ensure that benefits are achieved.Practical implicationsThe case study selected for this research work is based on a parking sensor housing, which is a plastic part assembled on the vehicle’s front and rear bumpers, therefore, with aesthetics concerns. The part produced with the conventional mould exhibits surface defects that, to be minimised (not eliminated), require a longer packing time to diminish the sink marks.Social implicationsThe economic impact of the use of SLM is relevant despite the low batch size for the case study presented. Energy savings are achieved due to scrap reduction and shorter cycle time.Originality/valueThe systematic methodology proposed for prior evaluation of the advantages of conformal cooling is possible to be applied both on small scale and high production series.

Precise shape nano-replication for an antireflective imaging lens using a mould with a thermal insulation layer

A nanostructure transfer process with precise shape accuracy was investigated for application to an imaging optical lens. For a nanostructure transfer process by injection moulding, the temperature of the mould must be higher than the melting point of the polymer. Therefore, precise shape accuracy is not a sufficient specification for an imaging optical lens. Using a mould with a thermal insulation layer for the nanostructure transfer process, the temperature of the mould was evaluated to be 20 °C lower than that of a conventional mould because the heat energy was accumulated by the thermal insulation layer. Notably, the precise shape accuracy was 6 times that of a conventional mould. When using a mould for developing an antireflection structure, an optical lens with a transferred nanostructure exhibited low antireflection of less than 0.5% and precise shape accuracy of 0.5 μm at a diameter of 5 mm. These specifications are sufficient for an optical imaging lens. We suggest that the mould is suitable for application to imaging lens.

3D printable inter cross-linking network (ICN) gels for reversible transparency control with water content

A patient-specific phantoms, which are equivalent to human tissues, is needed in the experimental dosimetric verification before radiotherapy treatments. Most of the shape of gel phantoms have been structurally limited because of the fabrication method using mold technique. The present study focuses on direct freeform fabrication of gel phantom with the customized optical 3D gel printing system. Life-sized gel phantoms were replicated using conventional mold techniques, the 3D printer with two-step sequential free-radical polymerization process and inter cross-linking network gels as 3D printing materials. The gel phantoms are ultraviolet light-sensitive instead of radiation. The ultraviolet sensitivity of the gel phantoms (using mold techniques) with different molar ratios were experimentally evaluated with transmittance measurements, and were theoretically estimated by curve fitting to the observed data. This measurement gave us the insight that more vinyl monomers in the gel phantoms caused rapid polymerization and visibly opaque as well as conventional gel dosimeters. We confirmed that inter cross-linking network gel was 3D printable with the customized 3D printer, with resolution of fabrication 500 μm, as pre-finger-shaped phantom. The cross section of 3D printed gel phantom showed the distribution of opacity, that is, the distribution of UV irradiation. We expect that the 3D printer specialized gel materials and ICN gels are feasible for practical fabrication method of 3D gel phantom.

Case Studies on Integrating 3D Sand-Printing Technology into the Production Portfolio of a Sand-Casting Foundry

Metal casting foundries all across USA are increasingly adopting the recent development in additive manufacturing including 3D sand printing (3DSP) due to its unique ability to fabricate molds and cores without any tooling requirement such as patterns, cores, core boxes, flasks among others. This new method of rapid mold fabrication can accelerate process cycle times, reduce shrinkage defects, offer part consolidation, functional integration and customization that could facilitate the growth of foundry industries. This study demonstrates how the adoption of 3DSP technology has contributed to a conventional ferrous metal casting foundry that specializes in manufacturing impellers, turbine housings and other mining equipment. Four industrial case studies are presented to illustrate novel opportunities via 3DSP. These case studies validate that 3DSP has the ability to (1) reduce shrinkage by allowing casting in optimal orientation without hard-tooling requirements, (2) reduce lead time through rapid mold fabrication by easier facilitation of nesting multiple parts into a single mold, (3) allow hybrid molding by integrating 3DSP with conventional mold making and (4) fabricate tooling-less complex castings, respectively. Findings from this study would help foundries rethink their design process from traditional pattern-drawing to a new and radical freeform-based design process via 3DSP.

Thermomechanical Optimization and Comparison of a Low Thermal Inertia Mold with Rectangular Heating Channels and a Conventional Mold

Molds used to manufacture high-performance composites currently do not meet the demand of manufacturers in terms of production rate due to massive mold designs, using straight-through heating channels, that are not thermally reactive. In this paper, using a thermal finite element model, the thermomechanical responses of an existing massive and conventional mold is observed; then, thermomechanical optimizations are carried out on a circular heating channel mold and on a rectangular heating channel mold. The objective of this paper is two-fold: (i) confirm the need to change design rules for molds considering technological aspects (e.g., pressure drop and fluid nature) and (ii) validate the advantages of an innovative concept of a low thermal inertia mold with rectangular heating channels. Results of this study confirm the need to reduce the mass of structures to increase heating rates and the importance of taking into account technological data (heat transfer fluid, pressure drop) to ensure the optimal convective exchange. After optimization, a decrease greater than 75% in heating time for the circular channel model and up to 88% for the rectangular channel model was observed. Moreover, the antagonistic nature between heating rate and thermal homogeneity of the molding surface and between heating rate and mechanical strength is confirmed.

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.

Multimaterial 3D Printed Soft Actuators Powered by Shape Memory Alloy Wires

Shape memory alloys (SMAs) have been widely used to fabricate soft actuators by embedding SMA wires into various soft matrices manufactured by conventional moulding methods or novel three-dimensional (3D) printing techniques. However, soft matrices of SMA based actuators are typically fabricated from only one or two different materials. Here, we exploit the great manufacturing flexibility of multimaterial 3D printing to fabricate various bending, twisting and extensional actuators by precisely controlling the spatial arrangements of different printing materials with different stiffnesses. In order to achieve a broad range of deformations, ten different printing materials were characterized and used in the actuators design. In addition, we developed a finite element model to simulate complex deformations of the printed actuators and facilitate the design process. The model incorporates a user defined material subroutine that describes the nonlinear temperature dependant behavior of SMAs. The results show the efficiency and flexibility of multimaterial 3D printing in tailoring the deformed shape of the SMA based soft actuators, which cannot be accomplished using conventional manufacturing methods such as moulding.

Structural and Mechanical Characteristics of Cu50Zr43Al₇ Bulk Metallic Glass Fabricated by Selective Laser Melting.

In this work, the structural and mechanical characteristics of Cu50Zr43Al7 bulk metallic glass (BMG) fabricated by selective laser melting (SLM) are studied and the impacts from the SLM process are clarified. Cu50Zr43Al7 alloy specimens were manufactured by the SLM method from corresponding gas-atomized amorphous powders. The as-built specimens were examined in terms of phase structure, morphologies, thermal properties and mechanical behavior. The x-ray diffraction and differential scanning calorimetry results showed that structural relaxation and partial crystallization co-exist in the as-fabricated Cu50Zr43Al7 glassy samples. The nano- and micro- hardness and the elastic modulus of the SLM-fabricated Cu50Zr43Al7 BMG were higher than CuZrAl ternary BMGs with similar compositions prepared by conventional mold casting, which can be attributed to the structural relaxation in the former sample. However, the macro compressive strength of the SLM-fabricated Cu50Zr43Al7 BMG was only 1044 MPa mainly due to its porosity. This work suggests that the SLM process induced changes in structural and mechanical properties are significant and cannot be neglected in the fabrication of BMGs.

Effect of similar element substitution on Fe-B-Si-Mo bulk metallic glasses studied by experiment and ab initio molecular dynamics simulation

Fe72(B, Si, Mo)28 bulk metallic glasses (BMGs) were successfully fabricated by conventional copper mold casting. The glass-forming ability of the Fe72B17Si5Mo6 BMG was enhanced by partial similar element substitution of Nb for Mo and Co for Fe, which was explained from the thermodynamic and atomic structural perspective. The thermal, magnetic and mechanical properties of Fe72B17Si5Mo6, Fe72B17Si5(Mo0.5Nb0.5)6 and (Fe0.5Co0.5)72B17Si5(Mo0.5Nb0.5)6 BMGs were investigated by experiment and ab initio molecular dynamics simulation. The Fe72B17Si5Mo6 BMG shows a high saturation magnetization (Ms) of 1.08 T, a low coercivity of 3.0 A m−1, a high compressive yield strength of 4330 MPa and an outstanding plastic strain (εp) of 2.6%. Through similar element substitution, the Ms of (Fe0.5Co0.5)72B17Si5(Mo0.5Nb0.5)6 BMG decreases to 1.01 T owing to smaller magnetic moment of Nb and Co than Mo and Fe, and the εp increases to 3.5% because of less 15xx pair with five-fold symmetry.

Can ICO Markets Offer Insights into Marketising Sustainable or Social Finance? Proposals for a Revolutionary Regulatory Framework

This paper aims to bring together two areas seemingly far apart in finance- the world of sustainable and social finance and the largely unregulated markets in initial coin offerings (ICOs). Insights of cross-fertilisation can be derived to deal with a question that sustainable and social finance has struggled with, viz, the scaling up of such finance by fund-raising in markets rather than through institutions or intermediaries. The gaps in finance for sustainable and social needs are well-canvassed. These gaps are largely due to the slow pace in successful marketization of such finance, perceived to be often incompatible with the needs and requirements of investors in conventional markets. Conventional investment instruments such as securities and other asset classes have attained characteristics of ‘investibility’ and ‘marketability’ that sustainable and social finance are not yet fully able to offer. Further, these characteristics are secured and reinforced by financial regulation of traditional financial instruments. Hence, sustainable and social finance continue to face obstacles in terms of scaling up and raising funds. We offer a proposal to scale up the marketization of sustainable and social finance, by building on insights derived from the controversial ICO markets. We argue that ICO markets hold insights for transforming sustainable and social finance into a different asset class altogether, and the application of these insights may greatly increase the marketization potential of such finance. In this proposal we move away from treating sustainable and social finance as securities or securitised assets, and propose regulatory reforms to support such a new asset class. These regulatory reforms move away from a merely incremental approach that is focused on encouraging conventional investors to diversify their portfolios to include sustainable and social finance. In this analysis, we are not seeking to fit sustainable or social finance into ICOs or suggest that they should take advantage of the hitherto unregulated ICO markets. We are also keenly aware of the nascent efforts in regulatory treatment of ICOs, especially in relation to the extension of securities regulation over ICOs by the US Securities and Exchange Commission. We argue that policy-makers would miss the innovative and transformative elements in ICOs if an approach is forced upon ICOs to submit to existing regulatory regimes for securities and commodities. We take a different approach that breaks away from the conventional mould, allowing new asset classes to be created and access to finance to be broadened. This result will crucially require the support of new regulatory policy. Our proposal has the potential to liberate sustainable and social finance to the widest markets possible. We capitalise on the wide and borderless appeal that ICOs have already gained, in reaching out to communities and forming new markets for sustainable and social finance. Our proposal ultimately seeks to integrate the social and commercial dimensions in a new way in fund-raising, towards the construction of a new form of capitalism based on the crowdsourcing society for creating value in an integrated social-commercial manner. This phenomenon, powered by technology, meshes the social and commercial dimensions in fund-raising and disrupts existing establishments of marketplaces where sustainable and social finance have been inadequately served.