Salah satu sistem mekanisme yang mengontrol dan mendistribusikan oli pelumas ke komponen mesin yang berputar adalah sistem pelumasan. Bagian-bagian mesin yang bergesekan satu sama lain rentan terhadap keausan, yang dapat dihindari atau dikurangi dengan pelumasan. Operasi dasar sistem pelumasan adalah menyemprotkan pelumas pada bagian-bagian mesin yang bergerak yang bersentuhan satu sama lain selama penyalaan.Mesin frais merupakan salah satu mesin yang memiliki sistem pelumasan. Pada mesin frais, sistem pelumasan berada pada meja mesin yang bisa bergerak dalam sumbu X, Y dan Z. Pelumasan meja mesin frais perlu dilakukan setiap hari saat mesin akan digunakan. Menurut standar umum mesin frais, pelumasan dilakukan dengan cara menarik tuas pompa pelumas sebanyak empat kali. Namun, karena sistem pelumasan dilakukan secara manual oleh operator, hal tersebut terkadang terlupakan oleh operator. Melihat hal tersebut, peneliti melakukan modifikasi sistem pelumasan yang bertujuan supaya bagian-bagian mesin yang mengalami contact sliding dapat beroperasi dengan otomatis. Metode penelitian ini dengan cara memodifikasi sistem pelumasan manual yang telah ada pada mesin menjadi otomatis yang dikontrol melalui arduino uno dan digerakkan oleh motor stepper. Pada saat pompa pelumas terhubung arus listrik, secara otomatis pompa akan memompa sebanyak empat kali.Motor akan berhenti berputar setelah selesai memompa. Sehingga prototype yang dibuat mampu bekerja pada mekanisme sistem pelumasan mesin frais konvensional secara otomatis menyemprotkan 10ml oli.

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The Electric Arc Furnace (EAF) prototype at the Morowali Metal Industry Polytechnic has the main component in the form of a transformer that generates heat actively. The increase in temperature that occurs in the transformer is caused by continuous loading. In addition, a significant and relatively high temperature rise in the transformer, can reduce the performance of the transformer. This research will design a transformer cooling system on the EAF prototype. The temperature of the transformer will be maintained at a certain temperature until there is no longer an increase in temperature due to loading. The wire-tube cooling system in the transformer uses water and transformer oil as the cooling medium. Regulating the flow rate of the water fluid in the copper pipe is expected to be able to further optimize the cooling process in the transformer. The results show that the design of the wire-tube cooling system is able to release the temperature of the transformer oil with a heat transfer rate that varies according to the flow rate of the cooling water fluid. Experiments carried out for 30 minutes resulted in a heat transfer rate of Qu 760.5 kJ/s with a water flow rate of 2.5 liters/minute, Qu 1661.2 kJ/s with a water flow rate of 5 liters/minute, Qu 2558.5 kJ/kg with a water flow rate of 5 liters/minute. the water flow rate is 7.5 liters/minute and Qu 3213.9 kJ/kg with a water flow rate of 9.20 liters/minute, this shows that the higher the water flow rate, the higher the heat transfer.

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The characteristic of natural convection heat transfer in a thermally asymmetric cavity is influenced by temperature differences and space between the heat source and cavity wall. The heat source is any bluff body placed inside the cavity. This research used a heated elliptic tube as the heat source inside the cavity. The three tubes are of 2.5 aspect ratio (AR) in a vertically aligned arrangement. The cavity was thermally asymmetric because three sides of the cavity were insulated while the other side was exposed to convection with ambient air. The clearance ratio (CR) as the ratio between the gap from the insulated wall to the major axis of the tubes to the space of the cavity is varied 0.4 and 0.6. while the pitch ratio is constant at 3.5a. this study analyzes the characteristics of heat transfer from the surface of the elliptical tube to the surrounding air experimentally and numerically. The result reveals that the highest heat transfer coefficient 0f 0.4 CR is higher than that of 0.6 CR. The numerical solution shows the contour and streamlines of the fluid flow in all conditions as the characteristics of natural transfer thermally asymmetric cavity.