Kekasaran Dan Morfologi Hasil Pengelasan TIG Baja Tahan Karat 316 Dengan Kadar Sulfur Berbeda

The presence of impurities in stainless steel can unexpectedly create a problem in welding. The difference of a small amount of impurities, from heat to heat, can induce the inconsistency in welding especially in automatic welding. This study is conducted to asses the influence of sulfur content of the steel on morphology of weld which is represented by the variation of weld pool and surface roughness of weld. The effect of sulfur on surface roughness of weld is studied in TIG welding of 316 stainless steels with different sulfur content. The influence of sulfur on the weld geometry, characterized by the ratio of depth and width of the weld (D/W), is studied in welding with various parameters. The variation of the weld geometry is conjointly studied in relation to the surface roughness of weldment. The effect of sulfur is also studied using a stationary arc with different current and duration. The variation of the diameter of a circular pool and the degree of protuberance which possibly emerged beneath the specimen is related to the sulfur content of the steel. The results of the study show the salient effect of sulfur on the surface roughness of weld. The surface roughness of steel with high sulfur content always more perturbed than that of steel with lower one; the different movement of liquid, characteristic of these two steels is posited to explain the difference. Greater degree of roughness is accompanied by a greater value of the ratio D/W. The results of the study with stationary arc show some points of a paramount importance. The effect of sulfur which hitherto considered advantageous to the formation of a weld with a higher ratio of D/W, turn out to be effective only in a specific range of welding parameters. In a different range, the weld geometry is more influenced by the arc characteristic, the anode spot

Optimization of Travelling Water Screen (TWS) Components Replacement in Cooling Water System (Case Study on PLTGU Muara Tawar Blok 1)

Traveling Water Screen (TWS) in cooling water system is one of the main cooling equipment of a Combined Cycle Gas Turbine (CCGT) generator, which has a considerable impact towards the steam turbine’s power output and thermal efficiency of the generator in general. This research aims to understand the distribution of TWS component failure which occurs in the filtration process of the cooling water system under the current operating condition, and operational expenditures correlated with it. The analysis started with the collection of TWS maintenance data between 2003 to 2017. Then, the distribution of failure is characterized by using available statistical software. Mathematical models were used to determine optimum replacement policy for each component, based on failure distribution data and replacement/maintenance cost. The optimum replacement interval and minimum replacement cost varies between TWS components. The optimum replacement intervals for each component are as follows: 43.4245 days for bearing bushing; 19.9785 days for bolt, sock head M.16; 40.9505 days for bolt, sock head M.12; 27.6088 days for rubber seal; 48.4359 days for pin, straight plain, 25.4 mm; 88.4978 days for ram, wiremesh; 69.471 days for pin, straight plain, 27/30 mm; and 29.2394 days for nut, hex M.8. The minimum replacement costs for each component are as follows: Rp4,383,400/day for bearing bushing; Rp5,706,850/day for bolt, sock head M.16; Rp12,671,400/day for bolt, sock head M.12; Rp7,247,630/day for rubber seal; Rp6,308,610/day for pin, straight plain, 25.4 mm; Rp5,522,590/day for ram, wiremesh; Rp5,032,190/day for pin, straight plain, 27/30 mm; and Rp4,770,530/day for nut, hex M.8. These findings were further integrated into the implementation of optimum maintenance strategy, especially for stock control, manpower resources smoothing, and maintenance expenditure planning in order to keep the performance of the generato

Optimization of Gigabit Passive Optical Network (GPON) Devices Replacement Interval

Entering the industrial era that is increasingly advanced and growing, reliable internet connection becomes a very important foundation for every business. Internet connection failure or downtime will be the obstacle and causes much loss both for businessman and for internet provider company. This research aims to find a solution on how to minimize internet connection failure. One of the various methods that can be used to overcome the problem is called preventive maintenance. This research is chosen to determine how far the role of preventive maintenance in reducing the risk of connection failure due to device failure. Several tools that used in this research, such as statistical distribution to determine the pattern of device failure, and mathematical formula to calculate the estimated duration of the downtime occurs based on the time of preventive maintenance was applied. From that calculation, it can be concluded the optimal time to apply preventive maintenance to minimize downtime duration. The results reveal that a decreasing downtime value happens when preventive maintenance is applied at the optimal age of the device. EI8E - 8FE Electrical Interface Card kit was reduced by 8.01% with an optimal age of 21.82 days. GTGH - 16 Port GPON Line Card devices were reduced by 5.46% with an optimal age of 16.69 days. EMTPDP-DC Power Board devices are reduced by 0.1% with an optimal age of 53 days. The GPON MSVG - Control & Switching Card device is reduced by 4.38% with an optimal age of 32.28 days. MTPD - Power Supply equipment is reduced by 1.2% with an optimal age of 92.35 days. The ETC8B - 8E1 / T1 CES Card device was reduced by 0.84% with an optimal age of 41.23 days

Nurse Scheduling Optimation with Various Assignment Pattern at ABC Hospital Using Goal Programming Method

In fulfilling health services in hospitals, the availability of human resources (HR) which includes doctors, nurses, midwives, and so on, plays a very important role. In terms of amount and dominant existence in the hospital in providing health services to patients is a nurse. The role of hospital management in maintaining the availability of nurses is to plan a good schedule. Without a good resource scheduling plan, the services will not be optimal and the costs will hard to control. This research aims to optimize the nurse scheduling. Existing schedule did not pay attention to specific time that have different load to another. Management feels that a lot of idle time is experienced by some nurses. Therefore, from the data that occurred in the past there will be observations that every 4 hours will occur how many services performed and how many nurses needed. Furthermore, by using Goal Programming method, several priority objectives are made, such as how to minimize the deviation of nurses needed in one shift or slot. Then how to minimize the excess target number of nurses who work in one week. And then minimize the excess number of nurses who work on the night shift. The suggested mathematical model has been implemented using Lingo Software. Work patterns have been suggested to improve schedules quality based on different load of services that occur in specific time. The suggested approach can be used for any similar staff scheduling problem in the next research

Studi Eksperimental Pengaruh Model Sistem Saluran dan Variasi Temperatur Tuang terhadap Prosentase Porositas, Kekerasan dan Harga Impact pada Pengecoran Adc 12 dengan Metode Lost Foam Casting

Metode pengecoran lost foam merupakan metode yang tergolong baru dalam industri pengecoran logam. Pada saat ini belum banyak industri pengecoran logam yang menggunakan metode ini dalam memproduksi benda cor. Sedikitnya industri yang menerapkan metode pengecoran ini, yang mendorong untuk melakukan percobaan pengecoran dengan menggunakan metode lost foam, dengan melakukan perbedaan variasi temperatur tuang dan variasi model sistem saluran. Proses pengecoran dengan metode lost foam ini menggunakan styrofoam sebagai polanya, yang ditanam dalam cetakan yang berisi pasir silika kering (tanpa pengikat) kemudian cetakan digetarkan untuk memadatkan pasir. Ketika logam cair dimasukkan ke dalam cetakan, maka styrofoam akan menguap sampai cetakan tersebut terisi penuh oleh logam cair. Dalam penelitian ini, parameter yang digunakan adalah model sistem saluran dan variasi temperatur tuang terhadap kualitas hasil coran, diantaranya kekerasan, harga impact, prosentase porositas dan struktur mikro. Material yang digunakan dalam pengecoran ini adalah ADC (Aluminium Die Casting) 12. Parameter pertama yaitu model sistem saluran meliputi saluran samping, saluran bawah, saluran bawah dengan 2 gate dan saluran bawah dengan 3 gate dengan temperatur tuang konstan 700°C. Parameter kedua yaitu variasi perbedaan temperatur tuang antara 700°C, 750°C, 800°C dan 850°C dengan sistem saluran samping. Dari hasil penelitian ini diperoleh bahwa sistem saluran samping memiliki prosentase cacat porositas paling sedikit dibanding sistem saluran lainnya yaitu sebesar 2,7535% dan memiliki harga impact rata-rata paling besar yaitu 0,0275 J/mm2 pada potongan 1 dan 0,0660 J/mm2 pada potongan 2. Variasi temperatur tuang berpengaruh terhadap banyaknya cacat porositas dan harga impact rata-rata. Temperatur tuang 700°C dibanding temperatur tuang yang lain memiliki cacat porositas paling sedikit dan harga impact rata-rata paling besar yaitu 0,0275 J/mm2 pada potongan 1 dan 0,0660 J/mm2 pada potongan 2. Namun dari hasil pengujian kekerasan baik pada parameter model sistem saluran dan variasi temperatur tuang tidak dapat menunjukan perbedaan yang jelas

Hasil Peer Review "Analisis Head Pompa Sentrifugal pada Rangkaian Seri dan Paralel"

Berikut hasil Peer Review "Analisis Head Pompa Sentrifugal pada Rangkaian Seri dan Paralel" oleh Prof. Dr. Ir. Abdullah Shahab, M.Sc. dan Dr. Muji Setiyo, ST., MT

Hasil Peer Review "Analisa perbandingan kekuatan hasil pengelasan TIG dan pengelasan MIG pada Aluminium 5083"

Berikut hasil Peer Review "Analisa perbandingan kekuatan hasil pengelasan TIG dan pengelasan MIG pada Aluminium 5083" oleh Prof. Dr. Ir. Abdullah Shahab, M.Sc. dan Dr. Muji Setiyo, ST., MT

Hasil Peer Review "Perbandingan Induction Hardening dengan Flame Hardening pada Sifat Fisik Baja ST 60"

Berikut hasil Peer Review "Perbandingan Induction Hardening dengan Flame Hardening pada Sifat Fisik Baja ST 60" oleh Prof. Dr. Ir. Abdullah Shahab, M.Sc. dan Dr. Muji Setiyo, ST., MT

Hasil Peer Review "Effect of Cutting Fluid and Spindle Speed on Surface Hardness in Turning AISI 4140 Steel"

Berikut hasil Peer Review "Effect of Cutting Fluid and Spindle Speed on Surface Hardness in Turning AISI 4140 Steel" oleh Prof. Dr. Ir. Abdullah Shahab, M.Sc. dan Dr. Muji Setiyo, ST., MT

Hasil Peer Review "Effect of Welding Using Electrodes With Certain Treatment on Stainless Steel 304 Using SMAW Welding"

Berikut hasil Peer Review "Effect of Welding Using Electrodes With Certain Treatment on Stainless Steel 304 Using SMAW Welding" oleh Prof. Dr. Ir. Abdullah Shahab, M.Sc. dan Dr. Muji Setiyo, ST., MT