Although die casting is a near net shape manufacturing process, it mainly involves a thermal process. Therefore, in order to produce high quality parts, it is important to determine casting-mold interfacial heat transfer coefficient and heat flux. In this paper the effects of different injection parameters (second phase velocity, injection pressure, pouring and die temperature) on heat flux and interfacial heat transfer coefficient were investigated experimentally and numerically. Experiments were performed in cylindrical geometry using a cast aluminum alloy A360 against H13 steel mold. Selected injection parameters were 1.7-2.5 m/s for second phase velocity, 100-200 bar for third phase pressure, 983-1053 K for pouring temperature and 373, 433, 493, 553 K for the die temperature. These parameters were used for both non-vacuum and vacuum conditions in the cavity of the mold. The effects of the application under vacuum conditions were also studied. Temperatures were measured as functions of time, using 18 thermocouples, which were mounted at different depths of casting and mold material. Measured and calculated temperature values are found compatible. Interfacial heat transfer coefficient h and heat flux q depending on the experimentally measured temperature values were calculated with finite difference method using explicit technique in C# programming language. In addition to experiments, Flow-3D software simulations were performed using the same parameters. Interfacial heat transfer coefficient and heat flux results obtained from Flow-3D are also presented in the study. Interfacial heat transfer coefficient has decreased as a result of increasing of temperature of mold and pouring. In addition, interfacial heat transfer coefficient values have increased slightly with the increase of injection speed and pressure. It was observed that the values of interfacial heat transfer coefficient and heat flux have also increased when vacuum was applied inside the cavity of the mold. When all injection parameters are considered, it is seen that the interfacial heat transfer coefficient varies between 92-117 kW/m 2 K.

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In automotive industry, noise from the road, engine and environment are undesirable sounds which impacts the driver and passengers. In automobiles, the connection between the gear shifter mechanism and the transmission is carried out through cables and these cables go through a passage between the engine and the passenger compartment and rubber-based grommet parts are using for insulation. In this study, a phenomenon is investigated for shifter grommet parts. For using low sound transmission speed of air, air chambers are positioned perpendicular to the sound direction in insulation materials and tested with impedance tube of samples transmission loss and sound absorption coefficient. At these tests EPDM samples were used. On these samples, 2 types of air chambers with 4 mm and 6 mm diameter were considered having either 2 or 3 whole body or blind holes. Results showed that in the air chamber with 3 blind holes, test sample results are best up till 8% void in the insulation material. On the other hand, most of the test samples with holes showed better results than the one’s without the hole and the results showed that using low sound velocity of air can help to achieve better sound insulation properties in similar applications.

Özet. Bu çalışmada, yüksek basınçlı döküm yöntemi ile üretimi gerçekleştirilen bir dişli kutusunun farklı termal ve dinamik parametrelere bağlı olarak Vulcan ve Flow3D simülasyon programları kullanılarak analiz işlemleri gerçekleştirilmiştir. Simülasyonlar sırasında kalıp sıcaklığı olarak 423 ve 573 K, döküm sıcaklığı olarak 953 ve 1053 K, enjeksiyon ikinci faz hızı olarak 1, 3 ve 5 m/s ve ikinci fazın başlangıcı olarak dolum ağzı ve topuk kısımları belirlenmiştir. Bu parametreler kullanılarak iki programda toplam 48 adet simülasyon yapılmıştır. Simülasyonların sonuçları porozite açısından incelenmiş ve enjeksiyon parametrelerinin parçada oluşan poroziteye etkisi araştırılmıştır. Materyal ve metot kısmında detayları verilen dişli kutusu için optimum döküm parametreleri sunulmuştur. Tüm deneysel parametreler dikkate alındığında optimum şartlar, ikinci faz başlangıç noktası için dolum ağzı, ikinci faz hızı 2 m/s, döküm sıcaklığı 1053K ve kalıp sıcaklığı 573K olarak belirlenmiştir. Bu parametreler için porozite miktarı Vulcan'da %2.72 ve Flow3D'de %3.24 oranında gerçekleşmiştir. Elde edilen sonuçlara göre ideal enjeksiyon şartlarında porozite miktarında %27 oranında azalma sağlanmıştır.Anahtar Kelimeler: Yüksek basınçlı döküm, Döküm simülasyonu, Porozite, Enjeksiyon fazı Casting Simulation of High Pressure Die Casting Depend on Injection ParametersAbstract. In this study, a gearbox produced by high-pressure die casting method is analyzed depending on different thermal and dynamic parameters by Vulcan and Flow3D simulation soft wares. In the simulations, die temperature is taken as 423 and 573 K, and casting temperature is taken as 953 and 1053K. In addition, Injection's second phase velocity is determined 1, 3 and 5 m/s respectively. Moreover, filling gate and biscuit are determined as the start point of second phase. 48 simulations are totally performed using those parameters in those soft wares. Simulation outcomes are studied in terms of porosity as well as the effects of different injection parameters on the product porosity. Optimal casting parameters for the gearbox given its details in the material and methods section of the study are also presented. When all the experimental parameters are taken into consideration, optimal conditions are determined as such that Filling gate is for the second phase start point, second phase velocity is 2 m/s, casting temperature is 1053K and die temperature is 573K. Porosity amount is 2.72% for Vulcan and 3.24% for Flow3D. According to the obtained results, porosity amount is decreased 27% in the ideal conditions.