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All Journal Jurnal Vokasi Mekanika
Durain Parmanoan
Universitas Negeri Padang

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Welding Defect Analysis in Low Carbon Steel SMAW Joints Using Visual Inspection and Liquid Penetrant Test as a Basis for Welding Quality Control Junil Adri; Durain Parmanoan; Andril Arafat; Fadhilah
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 3 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/znkhtk87

Abstract

This research is motivated by the importance of the ability of D3 Mechanical Engineering students in evaluating the quality of welded joints, because the welding results that appear unified are not necessarily free from surface defects. This study aims to analyze the types of welding defects in low carbon steel Shielded Metal Arc Welding  joints using Visual Inspection and Liquid Penetrant Test as the basis for welding quality control in vocational learning. The study used a quantitative descriptive design based on applied laboratories involving 48 D3 Mechanical Engineering students divided into three learning sessions. Each student produced one welded joint specimen, so that the total number of specimens analyzed was 48. Data were collected through visual inspection sheets, Liquid Penetrant Test result sheets, photo documentation, and recapitulation of welding defects, then analyzed using frequency, percentage, and technical interpretation of the causes of defects. The results showed that the most dominant defects were porosity with 17 specimens (35.42%), followed by undercut with 14 specimens (29.17%), excessive spatter with 12 specimens (25.00%), and irregular bead with 11 specimens (22.92%). Liquid Penetrant Test detected 64 defect indications, higher than Visual Inspection which detected 49 defect indications. From the quality category, 24 specimens were accepted, 18 required repair, and 6 were rejected. This study concluded that the combination of Visual Inspection and Liquid Penetrant Test is effective for identifying welding defects more comprehensively and can be the basis for quality control of welding learning that is more objective, systematic, and relevant to industrial needs.
The Influence of Fuel Injection Pressure on Engine Performance and Smoke Emissions in a Diesel Engine Using Palm Oil Biodiesel Blend Fuel Irlido Irwansyah; Dori Yuvenda; Yolli Fernanda; Durain Parmanoan
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 3 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/sqkbmp02

Abstract

This study was conducted to examine the effect of fuel injection pressure variations on diesel engine performance and Smoke Emissions in Yanmar TF105MR-DI diesel engines using B50 palm oil biodiesel mixture. The test was conducted at injection pressures of 210, 220, 230, and 240 kg/cm² with load variations of 1000, 2000, 3000, and 4000 W. Parameters observed included power, torque, Specific Fuel Consumption (SFC), thermal efficiency, and exhaust gas turbidity level as indicators of Smoke Emissions. The test results show that the change in injection pressure has an effect on the combustion process and the performance characteristics of the engine. An increase in injection pressure to 230 kg/cm² is able to improve the fuel atomization process so that the formation of the air-fuel mixture becomes more homogeneous. This results in higher power and torque than other pressure variations, along with a decrease in SFC values and increased thermal efficiency at all levels of load. However, when the injection pressure is increased to 240 kg/cm², the performance of the engine tends to decrease. This is suspected to be caused by the penetration of the fuel spray too far so that the mixing and combustion process does not take place optimally. In terms of emissions, a more optimal injection pressure also contributes to a reduction in the turbidity level of exhaust fumes.