Journal of Engineering Science and Technology Applications

Pengaruh Arus Pengelasan Smaw pada Dissimilar Logam Stainless Steel 201 dan Baja 1040 Terhadap Sifat Mekanik dan Struktur Mikro

Qomarul Hadi — 2025-09-30

The advancement of welding technology plays a crucial role in industrial development, especially in dissimilar metal welding, such as joining stainless steel 201 and carbon steel 1040. This type of welding often results in reduced mechanical properties at the joint due to differences in composition and physical characteristics. This study aims to investigate the effect of welding current variations on the tensile strength, hardness, and microstructure of dissimilar metal joints between stainless steel 201 and AISI 1040 steel. The welding method used is Shielded Metal Arc Welding (SMAW) with current settings of 85A, 90A, 95A, and 100A. Tests performed include tensile testing (ASTM E8M), hardness testing (JIS B 7725), composition analysis, and metallographic examination (ASTM E407-07). The results show that 95A is the most optimal current, producing the highest tensile strength and hardness values, particularly in the Heat Affected Zone (HAZ). Lower currents (85A and 90A) lead to insufficient penetration and fusion, a current of 100A generates the highest heat among all tested values. Composition analysis shows that stainless steel 201 primarily contains Fe, Cr, and Mn, while AISI 1040 is mostly composed of Fe. Variations in welding current also affect the microstructure, with the formation of phases such as widmanstätten ferrite and acicular ferrite, which significantly influence the mechanical properties of the welded joint.

Studi Losstime pada Kegiatan Produksi Pengupasan Tanah Penutup Pit Diamod PT Ceria Jasatambang Pratama

Apriyana Ningsih — 2025-09-30

PT Ceria Nugraha Indotama, precisely in the diamond pit managed by the contractor PT Ceria Jasatambang Pratama, there are 2 overburden stripping fleets, based on the production target data for March 2025, fleet 1 is 7,731 Bcm and fleet 2 is 3,257 Bcm with actual production of fleet 1 being 4,243.29 Bcm and fleet 2 being 5,365.00 Bcm. This research aims to find out the value and what are the losstime components of the load excavation tool in the overburden soil stripping activity at pit diamond 01 and pit diamond 02 of PT Ceria Jasatambang Pratama in March 2025. This activity is very important to support the smoothness of the nickel ore mining process. The research was conducted with field observation methods as well as primary and secondary data processing using microsoft excel software. The results of the study showed that the actual loss of time that was identified came from five main components, namely: rain and slippery roads (slippery), late starting work early shifts, breaks that started too early, delays in returning to work after a break and stopping work too early. Total losstime for one month in fleet 1 was recorded as 65 hours (average 2,2 hours per month), while fleet 2 was 60 hours (average 2,00 hours per month). This value shows that most of the effective working time is wasted due to these obstacles. The actual productivity of each fleet is calculated based on work efficiency, cycle time, swell factor and fill factor. Fleet 1 produces productivity of 812,25 tons/day and fleet 2 of 1,410,05 tons/day. This result shows the non-achieval of the production target in fleet 1, which is caused by the difference in bucket capacity on the loading and unloading equipment and the high loss time value. Suggested loss time reduction efforts include improving work discipline, implementation of P5M activities (five-minute talk), daily inspection (P2H), and regulation of refueling and slippery activities. This research is expected to be the basis for decision making in improving the operational efficiency of overburden mining. The average monthly value for fleet 1 was 2.2 hours with the losstime component being influenced by taking breaks too early, while for fleet 2 it was 2.00 hours, with the most influential losstime component consisting of starting late after a break.

Karakteristik Mineralogi Batubara Desa Tiktok Kecamatan Baraka Kabupaten Enrekang

Firaldy S — 2025-09-30

Coal is a solid, combustible sedimentary rock formed from the decay of ancient plants. Coal is brown to black in color and undergoes physical and chemical changes that increase its carbon content. The purpose of this study was to determine the mineral composition of the coal in the area. The sampling method used channel sampling, based on research conducted using XRD, obtained results: the upper sample was composed of quartz (69.8%), graphite (30.2%), the middle sample was composed of quartz (37.6%), graphite (33.8%), and albite (28.8%), and the lower sample was composed of albite (41.2%), quartz (30.0%), and graphite (28.8%).

Studi Desain Disposal Dan Perhitungan Kapasitas Out Pit Dump 3 Kabupaten Barito Selatan Provinsi Kalimantan Tengah

Muhammad Fathur Rachman — 2025-09-30

Disposal is an area designed and planned to accommodate overburden material from mining activities. The objective of this study is to create a disposal design and determine its design volume capacity. The research methodology applies a technical approach, such as processing topographic data as the basis for design, utilizing the situational map of the disposal area as a reference, and considering production targets. Based on the conducted study, a disposal design was developed from the lowest to the highest elevation, starting from the requested elevation of 80 up to the peak design at elevation 120. The calculation of the design volume capacity resulted in a total of 11,410,645 Bcm, obtained from each design stage by elevation.

Analisis Kualitas Batubara Berdasarkan Analisis Proksimat, Total Sulfur dan Kalori di Site Jhonlin Group PT Tribhakti Inspektama

Suriyanto Bakri — 2025-09-30

Coal is one of the fossil energy sources that remains the backbone of national energy needs, especially in the power generation and processing industries. The quality of coal greatly determines its economic value and efficiency of use, so a comprehensive analysis of coal characteristics is needed to determine its suitability for industry specifications and end-user requirements. PT Tribhakti Inspektama, as an independent inspection agency operating in the Jhonlin Group's working area, plays an important role in testing and monitoring the quality of coal to be marketed. This study aims to analyze coal quality based on the results of proximate analysis, total sulfur content, and calorific value in the Jhonlin Group mining area. The research method was carried out by taking coal samples from the stock file, preparing them, and analyzing them in the laboratory. The results of the study show that the proximate analysis of the samples was 4.13% ash, 20.87% moisture content, 42.21% volatile matter, and 32.77% fixed carbon. The coal in the study area is categorized as lignite with a low to sub-bituminous rating, so it still has the potential to be used for the cement industry and coal-fired power plants.