Jurnal Konversi Energi dan Manufaktur UNJ
Not a member yet
183 research outputs found
Sort by
Effect of SMAW Process Parameters on Hardness, Temperature Distribution, and Micro–Macro Structure of A36 Steel Welded Joints
No full textThe outer shell of an ISO tank plays a critical role in maintaining the integrity of its contents by withstanding temperature fluctuations, pressure, and radiation. Research on the fabrication of liquefied natural gas (LNG) tank outer shells therefore provides both scientific and practical value, particularly in ensuring mechanical reliability and structural performance. This study investigates the welding of American Society for Testing Materials (ASTM) A36 steel plates using shielded metal arc welding (SMAW) and evaluates the effect of welding parameters on mechanical and microstructural properties. Four specimens were prepared by varying welding current at 70 and 80 A on plate thicknesses of 4 and 12 mm. The results indicate that both current and thickness significantly influence the weld zone microstructure, with transformations from ferrite–pearlite in the base metal to widmanstätten and acicular ferrite in the weld metal. In terms of mechanical performance, the highest hardness value of 198.387 HVN was recorded in the 4 mm specimen welded at 70 A, demonstrating the strong dependence of hardness on combined current and thickness conditions. These findings contribute to optimizing welding parameters for the safe and reliable application of LNG tank outer shells
Sustainable Energy Transition in Remote Islands: Evaluating Wind–Solar Hybrid Systems to Support Commercial Green Tourism on Kei Kecil Island
No full textThis study aims to analyze the techno-economic feasibility of a hybrid microgrid system designed to support commercial green tourism infrastructure on Kei Kecil Island, Southeast Maluku. The research focuses on evaluating the investment feasibility of adding a 99 kW wind power plant to an existing system comprising photovoltaic (PV), diesel generators, and batteries. The methodology employs HOMER Pro simulation to assess key financial indicators and environmental impacts, with a particular emphasis on carbon emission reduction. Simulation results indicate that the proposed hybrid scenario offers a highly profitable investment strategy, characterized by a high return on investment (ROI) and a rapid payback period of under five years. These findings confirm that integrating wind energy not only significantly increases the renewable energy fraction but also suppresses the cost of energy to a competitive level compared to conventional generation. The novelty of this study lies in the specific analysis of wind turbine intervention on a brownfield architecture in a remote island setting, distinguishing it from typical greenfield design studies. This research provides a significant contribution to policymakers and investors as a validation model for energy transition supporting sustainable tourism in archipelagic regions
Analysis of Lead Time Reduction in Pre-Delivery Installation Process of Excavator Units at PT. XYZ Assembly Plant
No full textThe Pre-Delivery Installation (PDI) Department of PT. XYZ is tasked with carrying out the installation process of imported heavy equipment attachment units, including one of the leading excavator units. Obstacles that arise can affect installation productivity. The gap between the actual installation results of 78 units and the company's target of 156 units requires a solution or resolution to improve the process that can be implemented. Therefore, it is necessary to investigate the wait time associated with decreased productivity, which is the longest component of the installation process. This work has a purpose to analyze lead time of the excavator attachment unit installation process. The method is applied with a time study approach referring to data sheets and observations, then processing lead time data using pie charts, Pareto diagrams, and fishbone diagrams. Furthermore, we review the planning calendar, realization, and improvement engineering. Reduction is carried out by providing additional work personnel and procuring sanding machine tools to reduce the installation and critical time of the planning calendar. The realization condition for 562 minutes with the implementation of improvement engineering is reduced to 318 minutes. Thus, it can speed up implementation time of the excavator attachment in unit installation process to 224 minutes or 44%
Design of Coconut Milk Pressing Machine with Two Screw Shafts to Improve Extraction Efficiency and Quality
No full textCoconut milk pressing machines play an important role in coconut processing; however, conventional single-screw designs still face limitations related to pressure distribution and extraction stability. This study aims to design and analyze a coconut milk pressing machine, employing a counter-rotating two screw shafts configuration as an alternative to commonly used single-screw systems. The research methodology includes a reverse-engineering approach, analytical calculations to determine pressing capacity, power, torque, and pressure, and finite element analysis (FEA) simulations to evaluate the structural strength of main components. The analytical results indicate that the proposed design achieves a theoretical pressing capacity of 53 kg/h, with a shaft power requirement of 1.11 kW and a pressing pressure of 1.67 × 10⁵ N/m². FEA results show that the Von Mises stress and deformation remain below the allowable limits of the selected material, indicating a conservative, structurally safe design. All results presented in this study are theoretical and numerical in nature and have not yet been validated through experimental testing. The novelty of this work lies in the application of a counter-rotating two screw shafts configuration, which theoretically provides a more uniform pressure distribution than conventional single-screw systems without a significant increase in power consumption. Future work will focus on prototype fabrication and experimental testing to validate extraction performance, energy efficiency, and hygienic aspects
Effectiveness of Epoxy Coating on Metal Surfaces of NEW773CAT Heavy Equipment Units
No full textThis study investigates the effectiveness of the epoxy coating system on NEW773CAT heavy equipment unit operating in a mining environment. The research primarily focuses on the influence of surface preparation methods, dry film thickness (DFT), and coating type on corrosion resistance and adhesion strength. Field case studies, thickness measurements, and visual inspections were employed to assess the performance of coating system. The results reveal that average coating thickness of 396 μm significantly exceeds the minimum ISO 12944 category C5-I standard, which specifies a DFT of 320-400 μm for high corrosivity environments. The surface preparation process using high-pressure cleaning and power tool cleaning (ST 3.0) was found to produce an ideal substrate for epoxy coating application. The use of high-built epoxy mastic as the primer and Aliphatic Polyurethane as the top coat demonstrated excellent corrosion protection and optimal interlayer adhesion. The spray application technique resulted in a uniform coating with no visible defects. This study emphasizes the importance of combining effective surface preparation and precise coating specifications to ensure long-term protection of metal surfaces in harsh environments. The findings suggest that epoxy coating systems, when correctly applied and prepared, can provide robust protection against corrosion, extending the service life of heavy equipment exposed to aggressive conditions like those found in mining operations
Current Variation Effect on Hardness and Corrosion Resistance of Formed Weld Layer
No full textHardfacing over carbon steel was carried out using the SMAW apparatus. The sample was hard-faced with a single layer using HV 800 electrode with a 1G weld position. Different welding currents were used, such as 90, 100, and 110 A. After the weld, the sample was quickly immersed in distilled water. Cooled samples were cleaned with a chipping hammer and a wire brush. Afterwards, the samples were cut for hardness and corrosion testing. The highest hardness in the sample was welded using 110A, while the lowest hardness was welded using 90A. Increasing the current from 90 to 110 A could increase hardness by approximately 2.31%. The lowest current was used during welding, resulting in a lower corrosion rate. This means that the welding layer produced at the lowest current has greater corrosion resistance than that produced at higher currents. Reducing the current from 110 to 90 A could reduce the corrosion rate by approximately 44.33%. Finally, all three specimens meet the "good" criteria of corrosion resistance.
Comparative Characterization of Indonesian AISI 316L Stainless Steel and Commercial Femoral Stem for Artificial Hip Joint Applications
No full textThe development of the femoral stem, part of the artificial hip joint, requires a material with microstructures, mechanical properties, and chemical composition that meet the requirements of a medical implant. This study aims to characterize and compare Indonesian AISI 316L stainless steel with two commercial femoral stem implants used by patients, namely XYZ products from the United States and ABC products from India. The tests carried out on the three products include tensile tests, macro hardness, microhardness, microstructure observations, and chemical composition analysis. The tensile test results show that XYZ products have the highest ultimate tensile strength (UTS) of 1065.6 ± 11.7 MPa, while the Indonesian AISI 316L (IDN) and ABC products showed lower UTS values of 580.9 ± 0.3 and 536.3 ± 9.4 MPa, respectively. Microhardness tests showed that XYZ products achieved the highest hardness value of 306.0 ± 13.5 VHN with an increasing hardness gradient towards the surface. Meanwhile, the Indonesian AISI 316L materials showed a relatively homogeneous hardness distribution with an average value of approximately 197.5 ± 1.3 VHN. Observation of microstructures reveals differences in grain size and distribution, which correlate with microhardness values. Analysis of the elemental composition shows that all three materials exhibit characteristics of austenitic stainless steel with variations in the alloy element content. Overall, the results highlight the influence of microstructural features and alloy composition on mechanical performance. Although the Indonesian AISI 316L material evaluated in this study is not classified as implant-grade stainless steel, the findings provide a baseline reference for future material development. It emphasizes the need for strict compliance with implant-grade standards, manufacturing optimization, and surface treatment to enable potential application in femoral stem component
Development of a Portable Laser Engraving System for Small-Scale Manufacturing Applications
No full textThe portable laser engraving system developed in this study integrates an APM32F103 microcontroller, external flash memory (25Q128JV), and an FSC-BT986 Bluetooth module with an Android-based engraver application. The system is designed to address limitations of bulky and costly commercial engravers by offering a compact, low-cost, and wireless alternative for educational laboratories and small-scale manufacturing. Mechanical and electronic subsystems were designed and fabricated using a knockdown frame structure and 3D-printed components. Performance evaluation included functionality testing, wireless communication stability, motion accuracy, and engraving capability on wood, MDF, acrylic, and synthetic leather. The results show stable Bluetooth communication within an effective range of 8 m, an average motion accuracy error of 0.82%, and engraving depths ranging from 0.28–0.45 mm depending on material and laser parameters. The proposed configuration demonstrates technical advantages in wireless stability, portability, and ease of use compared to conventional wired microcontroller-based laser engravers
Passenger Seat Design and Analysis for Railway Executive Transportation
Full text linkThe design of executive chairs for trains was carried out to improve safety, comfort and aesthetics of the train. Seat design innovation was made by prioritizing passenger comfort and paying attention to the S curve of the passenger's spine. This research carried out a redesign of the Indonesian railway executive chair with the added advantage of a chair that can be tilted up to 40° from the initial position of 10°. After the design concept is selected, a simulation will be done on three critical parts of the train seat including chair frame, footrest, and footrest frame. According to investigation, there are facilities tailored to user needs, starting from a folding table, middle arm rest, reclining seat 40°, rotate system 180°, and footrest. The mechanism used for reclining seats with the help of a gas spring to adjust the backrest and a rotate system mechanism with plate bearings. Thus, the seat can be adjusted to the direction of the train's advance. The final chair dimensions of 1101x´1091´x632 mm and material ASTM A36, polypropylene, rubber
Performance and Efficiency Comparison of Human Waste Biogas and LPG Production in Modified Water Pump Engines
Full text linkAs daily needs and fuel prices continue to rise and non-renewable natural resources diminish, alternatives are needed to replace these energy sources with renewable energy. Data from the National Energy Council shows that in Indonesia, only 16.358 household biogas digester units have been installed, or about 1.6% of the total potential that can be utilized. This research aims to compare the performance of biogas from human feces with liquefied petroleum gas (LPG) as fuel for water pump engines. The method used is experimental, involving the modification of the carburetor on the water pump engine, followed by direct measurement and analysis of the water pump results using variations of biogas and LPG fuels. A literature review indicates that biogas has great potential as a renewable energy source, but its utilization in Indonesia remains very limited. In this study, the test variables include variations in pump speed at 3800, 5300, and 6600 rpm. The test results show that the mass flow rate of biogas compared to LPG yields the highest discharge at 6600 rpm (0.118: 0.150 m³/s). For both biogas and LPG fuels, the maximum shaft power of the water pump engine reaches 3.9 kW at 6600 rpm. The maximum waterpower generated by the water pump engine using biogas and LPG is 1.26 kW and 1.6 kW at 6600 rpm, respectively, while the maximum efficiency reaches 32% with biogas and 41% with LPG. Therefore, the higher the water pump engine speed, the higher the values of shaft power, engine power, discharge, and efficiency. The efficiency ratio comparison between biogas and LPG at 6600 rpm is 3:4