Pengaruh Pengaturan Jarak Elektroda Busi Pada Unjuk Kerja Motor Bensin (Effect of te Sparkplug electrode Gap on Gas Engine Performance)

Unjuk Kerja motor bakar sangat terganlung pada kesempurnaan pembakaran campuran bahan bakar dengan udara dalam ruang bakar di tiap-tiapsilinder. Untuk motor bensin, kesempurnaan pembakaran tersebut tergantung pada berhasil atau tidaknya loncatan bunga api/ listrik (pada elektroda busi) membakar semua bahan bakar yang masuk ke ruang bakar tiap-tiap silinder. Keberhasilan pembakaran tersebut sangat diperngaruhi oleh keberhasilan timbulnya loncatan bunga api di elektroda busi oleh sistem dan pengaturan waktu loncatan bunga api tersebut. Pada penelitian ini, faktor pengaturan waktu loncatan bunga api disesuaikan dengan data mesin sehingga yang menjadi variabel hanya faktor pertama. Penelitian dilaksanakan dengan menggunakan peralatan standard yang ada pada motor bensin di laboratorium konversi energi. Pengamatan unjuk kerja mesin dilakukan pada beberapa macam pengaturan jarak elektroda busi. Variasi jarak yang digunakan adalah 0,5, 0,6, 0,7, 0,8, 0,9 dan 1 mm. Dari basil pengamatan terlihat bahwa untuk mesin FORD CORTINA (1300 cc), jarak elektroda busi yang optimal berada di sekitar 0,8 dan 0,9 mm. Konsumsi bahan bakar spesifik hampir sama dengan jarak 1 mm tetapi memberikan daya yang lebih besar (setelah pembukaan katub 20 â 30%). Untuk keperluan/kondisi khusus (misal, pembebanan tinggi, konsumsi bahan bakar rendah), maka bisa dipilih jarak elektroda busi yang paling menguntungkan sesuai dengan data hasil pengamatan. Kata Kunci : Elektroda busi, Unjuk Kerja Mesin

Pengaruh Pemasangan Transistor Assisted Contact [TAC] dengan Beberapa Macam Coil pada Unjuk Kerja Motor Bensin

Transistor Assisted Contact (TAC) merupakan alat/unit tambahan yang dipasang pada pengapian konvensional motor bensin dengan maksud memperbaiki untai sistem pengapian konvensional dan unjuk kerja mesin. Setelah bebarapa tahun terakhir ini dipasarkan beberapa merk unit TAC, timbul beberapa pendapat dari pemakai TAC tentang manfaat pemasangan unit tambahan tersebut. Ada yang memuji tetapi ada juga yang mengeluh, karena pemasangan unit tersebut kadang-kadang justru menimbulkan kesulitan bagi pemakai. Hal tersebut yang mendorong penyusun melakukan penelitian ini. Penelitian dilaksanakan dengan menggunakan beberapa jenis/merk TAC yang ada dan beberapa jenis/merk coil yang banyak digunakan. Unjuk kerja mesin dengan pengapian konvensional dibandingkan dengan unjuk kerja mesin yang menggunakan alat/unit tambahan TAC pada sistem pengapiannya. Keuntungan pemasangan unit TAC : 1. Sistem pengapian masih mampu menghasilkan tegangan yang cukup pada elektrode busi untuk putaran mesin di atas 4000 - 5000 putaran per menit. 2. Beban pemutus arus mekanis menjadi lebih ringan karena arus dan tegangan yang melewati pemutus arus tersebut menjadi jauh lebih kecil. Umur pemutus arus mekanis akan menjadi lebih lama dan jarak waktu pengaturan sistem pengapian itu sendiri juga menjadi jauh lebih lama

Pengaruh kadar tambang (Cu) terhadap sifat mekanis aluminium matrix composite berpenguat alumina dibuat secara ekstruksi

The objective of this research is to find effect of copper on the mechanical properties of aluminium matrix composite (AMC), which is reinforced by alumina and made using hot extrusion. The amount of copper of 1;3 and 5wt% and 10wt% local alumina were added to the aluminium fine powder as matrix. Each was mixed using rotary mixer for 2hr. The mixture was then uniaxially compacted with a pressure 100 MPa to produce green body. The green body was then extruded at 600°C and ratio 4/9. Each composites was tested of bending strength, porosity. hardness and wear rate. From the data testing can be found effect of copper on the mechanical properties of AMC. The results show that mechanical properties decrease with inceasine of fraction of copper. The best mechanical properties such as bending strength, porosity, hardness and wear rate is on the AMC with 1wt% copper, there are 387 MPa, 0,5%, 80 VHN and 0,013 mg/MPa.m, respectivel

Study of the use of a micro hydro in knockdown container completed with a cylindrical form housing of francis hydraulic turbine to support the development program of energy self-sustainability for remote and isolated areas in Indonesia

With an intention to reduce the consumption of energy from fossil fuels and the CO2 emission in relation with the climate change solution, Indonesian Government has targeted that the role of the New and Renewable Energy (NRE) resources reaches at least 23% , or about 27 GW , in 2025 and it is expected to increase to the extent of about 134 GW in 2050 within the scenario of mixed energy supply. Geographically Indonesia has many remote and isolated areas with lack of appropriate infrastructure supports. But in the most of the areas, huge potential of new and renewable energy are available such as hydro energy is about 75 GW, biomass energy is about 32 GW and bio fuel is about 32 GW. The total utilization of the energy from small hydro energy up to this year for example is only about 300 MW. The significant obstacle in optimizing the utilization of small hydro energy in the areas is mainly on the infrastructure conditions and the local manufacture capabilities. Difficulties in mobilization of experts, skill worker , parts and constructions material result in very time consuming and costly for site construction. In this research a hydro turbine built in knock down container completed with a Francis turbine in cylindrical form housing is proposed and reported its performance on implementation. The hydro in a knock down container concept comes from the idea to manufacture hydro power solutions in a knock down container, readymade to be transported to installation sites. It can be easily manufactured in a quality controlled and cost effective environment, transported and installed in remote areas, to operate and maintain with minimal amount of equipment. It shows that the implementation of the unit in a remote area has reduced the total site construction time by 1/3 compared to the predicted one with conventional unit. The performance of the Francis turbine with cylindrical form housing has shown comparable with the conventional one which has volute form housing. The superiority was even more pronounced by introducing a deflection insert in its input flow channel. The insertion was capable to create more distributed flow into the runner. Efficiency of the turbine up to 80% was performed in this research. Local manufacture for turbine usually use many craft work and welding to built a volute form housing for the Francis turbine. The cylindrical form housing here has also proven significantly in reducing the time and price for the turbine manufacturing process

Study of the use of a micro hydro in knockdown container completed with a cylindrical form housing of francis hydraulic turbine to support the development program of energy self-sustainability for remote and isolated areas in Indonesia

With an intention to reduce the consumption of energy from fossil fuels and the CO2 emission in relation with the climate change solution, Indonesian Government has targeted that the role of the New and Renewable Energy (NRE) resources reaches at least 23% , or about 27 GW , in 2025 and it is expected to increase to the extent of about 134 GW in 2050 within the scenario of mixed energy supply. Geographically Indonesia has many remote and isolated areas with lack of appropriate infrastructure supports. But in the most of the areas, huge potential of new and renewable energy are available such as hydro energy is about 75 GW, biomass energy is about 32 GW and bio fuel is about 32 GW. The total utilization of the energy from small hydro energy up to this year for example is only about 300 MW. The significant obstacle in optimizing the utilization of small hydro energy in the areas is mainly on the infrastructure conditions and the local manufacture capabilities. Difficulties in mobilization of experts, skill worker , parts and constructions material result in very time consuming and costly for site construction. In this research a hydro turbine built in knock down container completed with a Francis turbine in cylindrical form housing is proposed and reported its performance on implementation. The hydro in a knock down container concept comes from the idea to manufacture hydro power solutions in a knock down container, readymade to be transported to installation sites. It can be easily manufactured in a quality controlled and cost effective environment, transported and installed in remote areas, to operate and maintain with minimal amount of equipment. It shows that the implementation of the unit in a remote area has reduced the total site construction time by 1/3 compared to the predicted one with conventional unit. The performance of the Francis turbine with cylindrical form housing has shown comparable with the conventional one which has volute form housing. The superiority was even more pronounced by introducing a deflection insert in its input flow channel. The insertion was capable to create more distributed flow into the runner. Efficiency of the turbine up to 80% was performed in this research. Local manufacture for turbine usually use many craft work and welding to built a volute form housing for the Francis turbine. The cylindrical form housing here has also proven significantly in reducing the time and price for the turbine manufacturing process

PARAMETRIC COST ESTIMATION USING ACTIVITY BASED COSTING FOR PRISMATIC PRODUCT MACHINING

The study is focuses on a parametric cost model to estimate cost at the early stages of prismatic product development by machining process. The initial phase of model development begins with the determination of cost based on Activity-based costing (ABC) method of trough the overhead cost allocation of some product variants. All the resources required in the machining process are grouped into cost centers similar rates in order to determine the cost center (cost center rate). The Resources are derived from financial statements based on costs incurred during the period of time. Cost activity is calculated based on the amount of consumption and tariff cost centers required of each activity. Main activity the machining process, which develop a cost model with its parameters is the cost driver activity (activity cost driver) concerning on the amount of production and batch sizes. Mathematical equation based feature dimension has been created to determine machining process time as one of  the parameters of the model, create a. Feature were classified into 4 (four) groups of slots / pockets, holes, drills and chamfer. They are used as input variables to calculate the machining time. Thus, input parameters into the cost equation are the available information at the design stage, namely: the number of tools, product weight, dimensions (size) and the type of product features