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Journal of Mechanical Engineering Learning
Published by Universitas Negeri Semarang
ISSN : 2252651X     EISSN : -     DOI : https://doi.org/10.15294/jmel
Core Subject : Engineering,
Mechanical Engineering
JMEL: Journal of Mechanical Engineering Learning published by the Mechanical Engineering Department, Faculty of Engineering, Universitas Negeri Semarang Indonesia, is a journal that contains scientific articles on mechanical engineering and mechanical engineering learning. Published articles in english by JMEL include the results of original scientific research findings and scientific review articles are new in mechanical engineering learning. JMEL publishes periodically six months.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 25 Documents
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Effect of activator spraying amount on the thickness and appearance of water transfer printing film coating results Gilang Supanto; Ahmad Roziqin; Febrian Arif Budiman
JMEL : Journal of Mechanical Engineering Learning Vol. 15 No. 1 (2026): June
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jmel.v15.i1.30246

Abstract

This research investigates the influence of activator spray quantity on the thickness and visual appearance of Water Transfer Printing (WTP) film coatings on Aluminium alloy 5052 surfaces. The study employed an experimental method, varying activator spray quantities at 2, 3, 4, and 5 times. Coating thickness was measured using a Coating Thickness Tester, while appearance was visually assessed by 10 experts based on surface cleanliness, substrate coverage, and pattern neatness. The results indicate a positive influence of activator spray quantity on both parameters. For coating thickness, increasing activator quantity consistently led to greater average film thickness, with a total increase of 63.06% from 2 to 5 sprays (averaging 17.81% per additional spray). Concurrently, the visual appearance improved across all criteria; surface cleanliness increased by an average of 32.62%, substrate coverage by 29.56%, and pattern neatness by 31.79% for each additional spray. The most drastic improvements in both thickness and appearance criteria were generally observed in the transition from lower to intermediate spray quantities, suggesting an optimal activator range for great WTP results.
Development of a Website-Based E-Module to Improve Student Learning Outcomes on Starter System Material at SMK Teuku Umar Ridha Al Rizqi; Bunyamin; Wahyudi; Dwi Widjanarko
JMEL : Journal of Mechanical Engineering Learning Vol. 15 No. 1 (2026): June
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jmel.v15.i1.30822

Abstract

This study aimed to develop and examine the feasibility and effectiveness of a website-based starter system e-module for Grade XI students in the Light Vehicle Engineering Department at SMK Teuku Umar. This study employed a research and development approach using the ADDIE model, which consists of Analyze, Design, Development, Implementation, and Evaluation stages. The effectiveness of the product was tested using a one-group pretest–posttest design involving 29 Grade XI TKR 1 students. The instruments used in this study included expert validation sheets, learning outcome tests, and a student response questionnaire. The feasibility test involved two media experts and two subject matter experts. The results showed that the developed e-module was categorized as very feasible, with validation scores of 92.36% from media experts and 91.66% from subject matter experts. The learning outcome test showed that students’ mean score increased from 47 in the pretest to 76 in the posttest. The paired-sample t-test indicated a significant improvement in students’ learning outcomes, with tcount = 18.36, which was higher than ttable = 2.048. The N-Gain score was 0.5582, or 55.82%, indicating a moderate level of effectiveness. Student responses reached 85%, categorized as very positive. Therefore, the website-based starter system e-module is feasible and moderately effective for supporting starter system learning. However, this study was limited to one class and did not involve a control group; therefore, broader trials with comparison groups are recommended.
Analysis of The Effect of The Intake Manifold Curvature Angle of The KZR Engine on The Characteristic of Air Fluid Flow Arga Fernando; Rizqi Fitri Naryanto; Ahmad Roziqin; Sonika Maulana
JMEL : Journal of Mechanical Engineering Learning Vol. 15 No. 1 (2026): June
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jmel.v15.i1.31136

Abstract

This research is to determine the effect of variations in the intake manifold curvature angle on turbulence intensity, turbulent kinetic energy, flow velocity, and fluid flow patterns. One effort to reduce excessive fossil fuel consumption is modifying vehicles to consume fuel more efficiently through a more complete combustion process. One such method involves modifying the intake manifold of a motorized vehicle. This study used FD-based numerical study with a quantitative approach to investigate changes in the curvature angle of the intake manifold. The aim of The modification process of the intake manifold structure was conducted on a 2012 Vario 125 (KZR) motorcycle through simulation. The purpose of this simulation is to conduct a fundamental analysis before implementing changes to the intake manifold structure. The geometric definition of the intake manifold was created using SolidWorks 2020, and the simulation was performed using Ansys Workbench 2022. The curvature angle variations of the intake manifold were 110°, 120° (standard), and 130°. The simulation results showed differences in outcomes for each curvature angle. The highest turbulence intensity, turbulent kinetic energy, and flow velocity were observed at the 110° angle. This indicates that modifying the intake manifold through simulation can influence turbulence flow during the combustion process. These findings can be considered to achieve better torque and power output in vehicles in the future.
The Effect of Stroke Up with Ignition Timing Variations on The Programmable CDIon The Engine Performance of The Gl Pro Neotech Motorcycle in 1997 Iqbal Aditya Nugraha; Dwi Widjanarko
JMEL : Journal of Mechanical Engineering Learning Vol. 15 No. 1 (2026): June
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jmel.v15.i1.31207

Abstract

Stroke-up modification and ignition timing adjustment are commonly used to improve motorcycle engine performance, yet their combined effect requires controlled empirical verification. This study examined the effect of a stroke-up crankshaft combined with programmable CDI ignition timing variations on compression pressure, torque, and power output of a GL Pro Neotech 160 cc motorcycle. Methods: A quantitative true-experimental method was applied through engine performance testing under controlled workshop conditions. The standard crankshaft was compared with a stroke-up crankshaft, while ignition timing was adjusted to 15°, 16°, and 17° before top dead center using a programmable CDI. Primary data were obtained from compression tests and chassis dynamometer measurements across 5000–10000 rpm, then analyzed descriptively using average values, tables, and performance graphs. Results: The stroke-up modification increased compression pressure from 12.43 bar to 15.67 bar, equivalent to a 26.1% increase. The 15° timing produced strong low-to-medium speed torque, while the 16° stroke-up configuration showed the most stable and superior performance at medium-to-high engine speeds, reaching 16.71 Nm at 6000 rpm and peak power around 7000 rpm. Conclusion: Stroke-up modification combined with 16° ignition timing is the most effective configuration for improving motorcycle engine performance under the tested operating conditions and rpm range.
The Effect of Camshaft Modification on Fuel Consumption and AFR Value on The Honda Supra X 125 Motorcycle Wahyu Hidayat; Abdurrahman; Ranu Iskandar; Rizqi Fitri Naryanto
JMEL : Journal of Mechanical Engineering Learning Vol. 15 No. 1 (2026): June
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jmel.v15.i1.49227

Abstract

This study investigated the effects of camshaft modification and fuel variation on fuel consumption and air–fuel ratio (AFR) in a Honda Supra X 125 motorcycle. An experimental design was employed using three camshaft configurations standard, touring, and racing and two fuels: pure Pertamax and Pertamax blended with an octane booster. Fuel consumption was measured at idle and 5000 rpm based on the time required to consume 20 mL of fuel, while AFR was measured under idle conditions. Each test was repeated three times, and the results were expressed as mean ± standard deviation. At idle, the standard camshaft produced the longest fuel-consumption time, reaching 8.14 ± 0.09 min/20 mL with pure Pertamax and 9.22 ± 0.06 min/20 mL with the blended fuel. At 5000 rpm, the touring camshaft with the blended fuel produced the longest consumption time at 3.20 ± 0.05 min/20 mL. The racing camshaft consumed fuel more rapidly, with the lowest idle value of 6.57 ± 0.35 min/20 mL using pure Pertamax. AFR values decreased from 14.02 ± 0.06 for the standard camshaft with pure Pertamax to 13.45 ± 0.06 for the racing camshaft with the blended fuel. These findings indicate that camshaft geometry and fuel composition influence fuel-consumption characteristics and mixture richness. The standard camshaft was most efficient at idle, the touring camshaft performed best at 5000 rpm, and the racing camshaft produced the richest mixture.

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