Deionized Water Electrochemical Machining Hybridized with Alumina Powder Polishing for Microcavity of M-333 Mold Steel

An electrochemical machining (ECM) process for microcavity fabrication with deionized water (DI-water) and an ECM polishing hybrid with alumina powder of 1.0 μm grains on a single micro-EDM machine are proposed. The process adopts tungsten carbide as tool electrode and M-333 tool steel as the mold material. It reveals that employing the 30 μm/min feed rate with 50 mA and 0.2 ms of pulse-width is suitable for DI-water electrochemical machining. The DI-water ECM process can achieve an excellent surface roughness at Ra 0.169 µm on a semispherical round cavity. Combining the ECM with hybrid polishing with the alumina powder can achieve a better profile for a much deeper cavity than pure electrolytic discharge machining. The hybrid ECM polishing can efficiently finish a micro square insert of 0.6 mm length at 64 μm depth. Such ECM milling can achieve an S-shaped microchannel of radius 1.0 mm and a slot of 1.0 × 0.5 mm2 with 110 μm depth, demonstrating its feasibility and the surface integrity with accurate profile and roughness of Ra 0.227 μm. This study provides a cost-effective scheme for micro mold fabrication with a conventional micro-EDM machine tool and an intuitive and convenient optional process. However, some micro-electrical discharges occurred due to the breakdown of insulation, which creates micro craters on the surface of the parts.

Effects of Different Mold Materials and Coolant Media on the Cooling Performance of Epoxy-Based Injection Molds

Metal additive manufacturing techniques are frequently applied to the manufacturing of injection molds with a conformal cooling channel (CCC) in order to shorten the cooling time in the injection molding process. Reducing the cooling time in the cooling stage is essential to reducing the energy consumption in mass production. However, the distinct disadvantages include higher manufacturing costs and longer processing time in the fabrication of injection mold with CCC. Rapid tooling technology (RTT) is a widely utilized technology to shorten mold development time in the mold industry. In principle, the cooling time of injection molded products is affected by both injection mold material and coolant medium. However, little work has been carried out to investigate the effects of different mold materials and coolant media on the cooling performance of epoxy-based injection molds quantitatively. In this study, the effects of four different coolant media on the cooling performance of ten sets of injection molds fabricated with different mixtures were investigated experimentally. It was found that cooling water with ultrafine bubble is the best cooling medium based on the cooling efficiency of the injection molded parts (since the cooling efficiency is increased further by about 12.4% compared to the conventional cooling water). Mold material has a greater influence on the cooling efficiency than the cooling medium, since cooling time range of different mold materials is 99 s while the cooling time range for different cooling media is 92 s. Based on the total production cost of injection mold and cooling efficiency, the epoxy resin filled with 41 vol.% aluminum powder is the optimal formula for making an injection mold since saving in the total production cost about 24% is obtained compared to injection mold made with commercially available materials.

Alat Pencetak Edible Straw berbasis Mikrokontroler

ABSTRAKPenggunaan plastik saat ini banyak digunakan diberbagai kegiatan masyarakat, dampak dari penggunaan plastik terlalu banyak menyebabkan polusi pada lingkungan. Penelitian ini bertujuan merancang dan membangun alat yang menghasilkan sedotan minuman dengan bahan yang ramah lingkungan, bahan yang digunakan menggunakan agar-agar rumput laut nutrijell yang aman untuk dikonsumsi. Alat pencetak sedotan dirancang menggunakan komponen elektronika, diantaranya sensor suhu DS18B20, mikrokontroler, elemen pemanas dan kipas. Tahapan dalam proses rancang bangun meliputi perancangan mekanik, material cetakan menggunakan stainless steel, perancangan sistem elektronika dan perancangan perangkat lunak. Hasil pengujian dari alat pencetak edible straw mendapatkan hasil sedotan yang bervariasi dari segi bentuk dan tekstur, pada proses kerjanya alat pencetak sedotan dapat mengatur waktu pemanas dari kisaran waktu 5 – 30 menit, sedotan tersebut dipanaskan selama 30 menit dari suhu awal dengan suhu terukur pada menit ke-30 adalah 62oC. Kata kunci: edible, sedotan, pemanas, mikrokontroler, agar-agar nutrijell ABSTRACTThe use of plastic is currently widely used in various community activities, the impact of using too much plastic causes pollution to the environment. This study aims to design and build a device that produces drinking straws with environmentally friendly materials, the materials used are using nutrijell seaweed jelly which is safe for consumption. The straw printer is designed using electronic components, including the DS18B20 temperature sensor, microcontroller, heating element and fan. The stages in the design process include mechanical design, mold material using stainless steel, electronic system design and software design. The test results from the edible straw printer get straws that vary in terms of shape and texture, in the working process the straw printer can set the heating time from a time range of 5 - 30 minutes, the straws are heated for 30 minutes from the initial temperature with a measured temperature in minutes 30th is 62oC.Keywords: edible, straw, heater, microcontroller, nutrijell jelly

Influence of the Mold Material on the Injection Molding Cycle Time and Warpage Depending on the Polymer Processed

The thermal properties of the mold influence the cooling situation in the injection molding process. While there are experimental studies investigating the influence of special mold materials, they are limited to few polymers. In this work, an extensive parameter study with the simulation software Autodesk Moldflow Insight was performed to analyze the influence of the polymer itself on the impact of the mold steel on cycle time and warpage. The investigated part was a box with two thickness variations. A conventional mold steel was compared with a steel grade featuring approximately double the thermal conductivity. Simulations were performed with 18 polymers covering the most common material families. The main finding of this study was that the influence of the higher mold conductivity on cycle time ranged from an almost negligible reduction (3%) up to a strong effect (24%), depending mainly on the used polymers, but also on the part thickness. For the cycle time reduction, a correlation was found, with the melt, mold and ejection temperature being the dominant influencing factors of the polymers. With this correlation, it was possible to estimate the potential of cycle time reduction for other polymers. The simulations also showed a positive influence of the higher mold thermal conductivity on part warpage.

Failures Related to Castings

The information provided in this article is intended for those individuals who want to determine why a casting component failed to perform its intended purpose. It is also intended to provide insights for potential casting applications so that the likelihood of failure to perform the intended function is decreased. The article addresses factors that may cause failures in castings for each metal type, starting with gray iron and progressing to ductile iron, steel, aluminum, and copper-base alloys. It describes the general root causes of failure attributed to the casting material, production method, and/or design. The article also addresses conditions related to the casting process but not specific to any metal group, including misruns, pour shorts, broken cores, and foundry expertise. The discussion in each casting metal group includes factors concerning defects that can occur specific to the metal group and progress from melting to solidification, casting processing, and finally how the removal of the mold material can affect performance.

Design, Production and Evaluation of 3D-Printed Mold Geometries for a Hybrid Rocket Engine

The feasibility of 3D-printed molds for complex solid fuel block geometries of hybrid rocket engines is investigated. Additively produced molds offer more degrees of freedom in designing an optimized but easy to manufacture mold. The solid fuel used for this demonstration was hydroxyl-terminated polybutadiene (HTPB). Polyvinyl alcohol (PVA) was chosen as the mold material due to its good dissolving characteristics. It is shown that conventional and complex geometries can be produced reliably with the presented methods. In addition to the manufacturing process, this article presents several engine tests with different fuel grain geometries, including a short overview of the test bed, the engine and first tests.

Influence of Mold and Heat Transfer Fluid Materials on the Temperature Distribution of Large Framed Molds in Autoclave Process

Massive composite components manufactured by autoclave curing in large framed molds are extensively used in the aerospace industry. The high temperature performance of the large framed mold is the key to achieving the desired composite part quality. This paper explores and summarizes the important thermal properties of metal and heat transfer fluid materials influencing the heating performance of large framed molds, with the aim of improving the mold temperature distribution. Considering the fluid–thermal–solid interaction inside the autoclave, a reliable computational fluid dynamics (CFD) simulation model was developed and verified by a temperature monitoring experiment to achieve the prediction of the temperature distribution of the large framed mold. Then, numerical simulations were designed on the basis of the CFD model, and the single-variable method was used to study the effects of the material thermal properties on the temperature performance of large framed molds. Our simulation predicts that when copper is used as the mold material, the temperature difference decreases by 30.63% relative to that for steel, and the heating rate increases by 3.45%. Further, when helium is used as the heat transfer medium, the temperature difference decreases by 68.27% relative to that for air, and the heating rate increases by 32.76%. This paper provides a reference for improvement of large framed mold manufacturing and autoclave process in terms of heating rate and temperature uniformity.

Design and Development of a Mold for Patternless Casting Using AM/3D Printing

Additive manufacturing is a technology that is influencing every facet of manufacturing such as casting. 3D printing in particular has the potential to revolutionize castings in terms of precision and time taken in production. Patternless molds increase the efficiency of the casting process for large scale manufactured components. Therefore, ceramic based molds can be utilized for low temperature alloy parts such as mounting brackets. Nowadays, 3D printing technologies allow the direct printing of these molds. This is possible with the aid of CAD modelling of the casting mold which allows instant printing of patternless molds. The aim of this work is to introduce an approach to prepare a 3D design for a casting mold that can be manufactured using 3D printing technology. Mold design was made using Solidworks software according to standardized calculations from which cope and drag components were extracted. Candidates for potential mold material are highlighted along with advantages & limitations of utilizing 3D printing methodology.