Increasing the Sustainability of the Hybrid Mold Technique through Combined Insert Polymeric Material and Additive Manufacturing Method Design

To reduce plastic waste generation from failed product batches during industrial injection molding, the sustainable production of representative prototypes is essential. Interesting is the more recent hybrid injection molding (HM) technique, in which a polymeric mold core and cavity are produced via additive manufacturing (AM) and are both placed in an overall metal housing for the final polymeric part production. HM requires less material waste and energy compared to conventional subtractive injection molding, at least if its process parameters are properly tuned. In the present work, several options of AM insert production are compared with full metal/steel mold inserts, selecting isotactic polypropylene as the injected polymer. These options are defined by both the AM method and the material considered and are evaluated with respect to the insert mechanical and conductive properties, also considering Moldex3D simulations. These simulations are conducted with inputted measured temperature-dependent AM material properties to identify in silico indicators for wear and to perform cooling cycle time minimization. It is shown that PolyJetted Digital acrylonitrile-butadiene-styrene (ABS) polymer and Multi jet fusioned (MJF) polyamide 11 (PA11) are the most promising. The former option has the best durability for thinner injection molded parts, and the latter option the best cooling cycle times at any thickness, highlighting the need to further develop AM options.

TREATING WASTE SLUDGE FROM WATER-PURIFICATION PLANTS WITH THE GEOPOLYMERIZATION METHOD

Treatment of the sludge from water-purification plants is becoming more and more urgent due to the inability to increase its storage area. To avoid CO2 emissions, the use of non-Portland cement binders is recommended. The application of geopolymerization of waste sludge (WS) from water-purification plants is a novel solution. Curing conditions including high temperature, pressure or microwaves enhance the formation of geopolymer bonds. This paper presents the results of a research on the treatment of the WS of the Thu Duc water-purification plant (Vietnam) with the geopolymerization method. Solid phases were prepared by mixing the WS and fly ash (FA). The FA proportions of the solid phases were (10, 40, 70) w/%. The alkali-activated solution (AAS) was a mixture of a 40 w/% NaOH 6M solution and 60 w/% water glass (WG: Na2O.nSiO2 with n = 1.75 and volumetric density r = 1.40 kg/L). The geopolymer materials were mixtures containing an 80 w/% solid phase and a 20 w/% liquid phase of the AAS. Geopolymer samples were formed in a cylindrical steel mold with a diameter of 10 mm at a high pressure. The samples were cured in a 112 W microwave oven for 30 s or in a dryer at 110 °C for 24 h. The compressive strength and volumetric density of both sample groups were determined and compared to each other. The formation of geopolymer bonds was investigated using XRD, FTIR and SEM.

Karakteristik Sifat Mekanik Wadah Makanan dari Limbah Daun Pisang Kering

The objective of this research is to determine the physical quality of food media, consisting of small plate, large plate and small bowl. The method used of this research is testing the water absorption and resistance of the food media’s temperature. The process of making a food media using a stainless steel mold which is heated using a food thermometer with 100 and a load of 10 kg as a pressure, then it is printed for 5 minutes with 4 times taking the data for each food media. There are two testing of food media, the first test is water absorption with 29.5 for 125 miles into a small plate, 200 miles into a small bowl and 250 miles into a large plate for 60 minutes, the average value of the water absorption test for the Non-woven food media consists of three forms food medias have 0.00 as the same result, meanwhile woven media such as small plate has 65.00 , large plate has 44.83 and small bowl has 66.68 . Second test is resistance of the food medias based on temperature parameters. The temperatures used were 40, 60, 80 for non-woven food media consists of three forms food media which had few change after drying, while for woven food media consists three forms of food media had the same results, that is seepage (leaking) in the food media.

Investigation of the effect of addition of boron nitride on microstructure and mechanical properties of cast iron brake materials used in railway vehicles

In this study, characterization of cast iron break shoes used in locomotives and the effect of BN addition and BN addition on microstructure and mechanical properties by using powder metallurgy (PM) method by adhering to the chemical composition of cast iron break shoes were investigated. In this context, cast iron sabers were chemically analyzed and all elements were supplied in powder form, and then BN added powder compositions were produced by cold and hot pressing technique. A total of 4 different compositions were created without BN, with 0.25, 0.5 and 1 % BN addition. Cold pressing was made in a steel mold with a diameter of 10 mm under 700 MPa pressure under room conditions. Hot pressing was carried out in a graphite mold with a diameter of 15 mm in an argon atmosphere under a pressure of 45 MPa at a temperature of 900 °C. Then the cold and hot pressed samples were sintered at 1 200 °C for 2 hours in argon atmosphere. Density measurement of the produced compositions, microstructure examination, micro hardness measurement were made. Generally, in density measurements, the densities of the samples subjected to hot pressing were higher than the cold pressing process. The hardness value decreased in parallel with the addition of BN. Keywords: Brake shoe; powder metallurgy; microstructure; mechanical properties

Synthesis of AA7075 Based 10 wt.% Graphite Reinforced Composites for High Damping Capacity

The damping capacity improvement in under seawater for torpedo cone is the main of the research work. In the proposed work, an induction furnace was used to fabricate aluminum alloy AA7075 by melting individual elements such as pure Al, Zn, Mg, and Cu, followed by 10 wt.% graphite with varying sizes of reinforcement C1 (3 to 10μm), C2 (53 to 66μm), and C3 (106 to 150μm). Ingot casting was made in steel mold of 45 45 120mm3 and then hot forged at 490ᵒC, followed by solutionizing and artificial aging. Composites characterized for optical, SEM, hardness, and DMA analysis for loss factor. The improved performance in damping capacity by 50% observed for the threshold modulus of particulate (volume to the surface) for C2 composite. The processing cycle of fabrication of composites has been established.

Effect of layer thickness on residual monomer release in polymerization of bulk-fill composites

The aim of the present study was to investigate and compare the quantity of residual monomers leached from the bulk-fill composites with different compositions polymerized at varying layer thickness. Three bulk-fill (X-tra-fil, Beautifil Bulk Restorative, Fill-Up) and a nanohybrid composite (Filtek Z550) were used for the study. The composite resin samples were prepared with a stainless steel mold. For each composite, two groups were constructed. The samples in the first group were prepared using the 2 + 2 mm layering technique. In the second group, the composite samples were applied as a 4 mm-thick one layer and polymerized. Then, each composite samples were kept in a 75% ethanol solution and residual monomers released from composite resins were analyzed with an HPLC device after 24hour and 1 month. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Except the Fill-Up, all of residual monomer elution from the bulk-fill composites was significantly affected by the layer thickness (p < 0.05). The greatest monomer release was detected at 1 month after polymerization as a single 4 mm layer for Beautifil Bulk Restorative. Fill-Up composite showed similar residual monomer release in polymerization at different layer thicknesses compared to other composite resins. In the 2 + 2 mm layering technique, the least monomer elution was detected in the Filtek Z550 composite group. While Bis-GMA was the most released monomer in X-tra fil composite, UDMA was the most released monomer in all other composite resins. During polymerization of the bulk-fill composite, the layer thickness of the composite applied may affect the amount of residual monomers released from the composite resins. Conventional composites may release less monomer than bulk-fill composites when used with layering.

Flexural Behavior of Sandwich Composite Made of JFRP Honeycomb as Core and GFRP as Skin

The increasing demand of lightweight, strong and sustainable materials in aerospace, automobile and marine sectors is leading towards the development of new materials and structures. The sandwich composite is one of them which is well-known for their high strength to weight ratio and the fiber based sandwich structures with cellular core show comparatively good mechanical, acoustic, thermal and energy absorption properties than metallic cellular structure. The purpose of this work is to fabricate a sandwich structure with jute fiber reinforced polymer composite (JFRP) as core and glass fiber reinforced polymer composite (GFRP) as face sheet and to investigate bending properties of the fabricated structures for varying face sheet thicknesses. Skin and core honeycomb strips of the sandwich composites were manufactured using hand layup method and steel mold was used to obtain honeycomb shape. Flexural test results show that face sheet thickness has significant effect on the flexural behavior such as peak load, flexural strength and energy absorption. The failure mechanism during bending tests were also identified which would serve as a basis for future improvement of manufactured composites. The delamination at the interface between the core and the face sheet was the first catastrophic failure during bending. The presented sandwich structures are able to carry a significant amount of load even after failure.

The dependency of the microhardnes on microstructure and solidification parameters of directionally solidified Al–4.5wt.%Cu in clay mold

Improvement of material properties is achieved by controlling parameters involved in the solidification process; therefore, understanding them and their implication are essential. This work investigated the dependency of solidification parameters (cooling rate (TR), growth rate (VL), local solidification time (tSL), temperature gradient (G)), microstructure parameters (primary (λ1) and secondary (λ2) dendrite arm spacing), and micro-hardness values (HV) of Al-4.5wt.%Cu in the clay mold. The samples were directionally solidified in Bridgman vertical apparatus and the temperature is recorded during the cooling. The solidification parameters were obtained from the cooling curve. The microstructures and micro-hardness were characterized using an optical microscope and micro-hardness tester. The microstructure parameters were measured and plotted as functions of solidification parameters using linear regression. The relation between HV and microstructure parameters are analyzed. The results show the λ1 and λ2 change inversely with solidification parameters except for tSL. Comparison to other works shows the exponent values of solidification parameters of the clay mold are lower than that of the carbon and stainless-steel mold. The exponent value of λ2 in the clay mold is -0.183, close to the value in the graphite mold. The clay has the potential as mold material since it characteristic close to the graphite.

Evaluation of Mechanical Properties for Selected Dental Composite Resin Polymerized by Light Curing Technology at Different Thickness

The objectives of this study were to estimate the effect of the blue light cure unit on the compression force and hardness for composite resin nanoCeram at different thickness. The basic material used in this study was Ivoclar Vivadent Tetric N-Ceram Light Cured Hybrid restorative composite resin. The samples were cured by applying a (LED.F) unit Blue phase in a wavelength emission spectrum (494 NM) was used.60 disc-shaped specimens [9 mm diameter at (0.5, 1) mm thickness and 10 mm diameter at (1.5) mm thickness] were prepared using a stainless steel mold for hardness and compressive strength measurements. A composite resin was polymerized with an aid of a ( DC 5V/1A) lamp for (10, 20 and 30) sec .Three specimens were used for each group.The results were analyzed using (linear logarithmic, quadratic, linear and power) test.The different groups showed significant variability in relation, with a significant interaction between the groups.The result showed that the greater thickness more efficient for polymerization than small thickness and the long irradiation time more efficient for polymerization than short irradiation time, long irradiation time diffusion in deep portions of the sample convert to polymer and this provide good polymerization and then good mechanicalproperties.

Design of ecological masonry piece for non-structural walls

In the research work in the methodological aspect, the tongue and groove Block was designed (geometry) in AutoCad, based on the NMX-C-038-ONNCCE-2004 standard; It was included in the material with which the Block was manufactured, crushed polypropylene plastic (PP) to reuse materials that are polluting, and in this way an ecological Block was made, later it was manufactured complying with the NMX-X-159 standard. ONNCCE-2004 the steel mold for the Block. For the analysis and results, a press was used to test the compression pieces established by the NMX-C-441-ONNCCE-2013 Standard for non-structural blocks. In the laboratory, the initial water absorption test was carried out with the NMX-C-037-ONNCCE-2005 in three pieces of blocks, in addition, the MATLAB software was used to obtain the effort-time graphs of the pieces of block with the different dosages of recycled plastic material. The research concludes that the reuse of polypropylene plastic to make blocks will help reduce environmental pollution. The results of the compression tests were satisfactory for non-structural blocks. The initial maximum water absorption tests to which the blocks were subjected, comply for exterior and interior walls.