Logic : Jurnal Rancang Bangun dan Teknologi

Evaluation of Lathe Operating Conditions Based on ISO 10816 Using the Correlation Between Spindle Vibration and Surface Quality

Talifatim Machfuroh — 2026-07-31

The evaluation of machine tool operating conditions is commonly performed based on mechanical reliability, while its direct relationship with the quality of machined surfaces is still rarely quantified. This study aims to evaluate the operating condition of a conventional lathe based on ISO 10816 by analyzing the correlation between spindle vibration and surface roughness. Experiments were conducted on a Dixon CQ6236X1000 lathe with variations in feed rate (0.104–0.835 mm/rev) and depth of cut (0–1.5 mm) at a constant spindle speed of 460 rpm. Spindle vibration was measured in terms of root mean square (RMS) velocity (mm/s) in the vertical and horizontal directions, and frequency-domain analysis was performed using Fast Fourier Transform (FFT). Surface roughness was evaluated using Ra, Rq, and Rz parameters. The results show that the RMS vibration values range from 0.4 to 2.5 mm/s, which correspond to Zone B and Zone C of ISO 10816-3 class I. At Zone B, the surface roughness values are relatively low (Ra = 2–6 µm), indicating stable machining conditions. However, when the operating condition shifts to Zone C, the surface roughness increases significantly, with Ra values exceeding 10 µm under certain cutting conditions. The correlation analysis between RMS vibration and surface roughness yields a coefficient of determination of R² = 0.399, indicating a moderate positive relationship. FFT analysis reveals that the dominant vibration components are associated with spindle rotational frequency and its harmonics, indicating the presence of mild regenerative chatter without evidence of bearing defects.These findings demonstrate that ISO 10816 can be utilized not only as a mechanical acceptability standard but also as a predictive indicator of surface quality in turning operations. The results provide a useful reference for integrating vibration-based condition monitoring with machining quality control in both industrial and educational workshop environments.

Development of a Solar-Powered Portable Watering Device Using an Ergonomic Approach to Improve User Comfort and Reduce Costs

Firman Ardiansyah Ekoanindiyo — 2026-07-31

Farmers in many rural areas still depend on gasoline-powered irrigation pumps, which create recurring fuel costs, noise, emissions, and awkward operating postures. Existing studies have widely discussed solar-powered irrigation systems and automatic watering technologies; however, limited attention has been given to a portable prototype that simultaneously integrates renewable energy use and ergonomic design for small-field operation. This study developed a solar-powered portable watering device and evaluated its technical and ergonomic performance in the Sido Maju Farmer Group, Kendal Regency, Indonesia. The prototype used a 350 Wp photovoltaic panel to supply a DC pump mounted on a wheeled frame. The ergonomic configuration was determined from farmers’ anthropometric dimensions, including a handle height of about 95 cm, frame height of 110–120 cm, and wheel diameter of 30 cm. The study applied a prototype-development approach followed by field trials, direct observation, and user questionnaires. Quantitative indicators included fuel-cost reduction, watering duration, mobility, and comfort scores, while qualitative data were obtained from farmer interviews. The results show that the proposed device reduced direct fuel expenditure from approximately Rp1,200,000 per planting season to Rp0, equivalent to about Rp4,800,000 in annual savings. The ergonomic evaluation also showed high user acceptance, with average scores of 4.6/5 for ergonomics and working posture, 4.7/5 for environmental working conditions, and 4.4/5 for efficiency and ease of use. These findings indicate that the device offers a practical contribution by combining solar energy utilization, portability, and ergonomic improvement in one agricultural watering system. The prototype can therefore support lower operating costs, better user comfort, and more sustainable irrigation practices for small-scale farming.

Effect of Pack Carburizing Temperature on the Surface Hardness of ST37 Low Carbon Steel Using Coconut Shell Charcoal

Made Ery Arsana — 2026-07-31

Steel is extensively utilized in engineering and manufacturing industries due to its mechanical reliability, availability, and cost-effectiveness. Low carbon steel ST37, while exhibiting good ductility, weldability, and machinability, possesses relatively low surface hardness and limited wear resistance, restricting its performance in components subjected to friction and mechanical loading. This study aims to evaluate the effect of pack carburizing temperature on the surface hardness of ST37 low carbon steel.

The carburizing process was conducted at three different temperatures (900°C, 1000°C, and 1100°C) with a constant holding time of 30 minutes. Coconut shell charcoal combined with CaCO₃ was employed as the carburizing medium, followed by water quenching to promote martensitic transformation. Surface hardness was measured using the Rockwell B (HRB) scale, and statistical analysis was performed to assess data reliability.

The experimental results showed a gradual increase in average hardness from 48.3 HRB (untreated) to 48.6 HRB (900°C), 48.9 HRB (1000°C), and 49.1 HRB (1100°C), representing a maximum improvement of 1.65%. Although the increase was relatively modest and statistically non-significant at the 95% confidence level, the consistent upward trend confirms that carburizing temperature influences carbon diffusion behavior and contributes to surface strengthening.

These findings indicate that temperature variation plays a role in enhancing the surface characteristics of ST37 steel, while further optimization of soaking time and microstructural analysis is recommended to achieve more substantial hardening performance.

Design of a Fuzzy Logic Based Control System for BLDC Motor Speed and Cooling Fan Using Error and Error Change

Adawiyah Aulia — 2026-07-31

This study presents the design and simulation-based evaluation of a fuzzy logic controller for a 48 V, 10 kW BLDC motor system integrating speed control and thermal management through a cooling fan. The controller employs four input variables, namely RPM error, change in RPM error, temperature error, and change in temperature error, within an 81-rule fuzzy inference system using triangular membership functions. Minimum-based rule evaluation, maximum aggregation, and weighted-average defuzzification are applied to generate PWM control signals. An interactive GUI-based simulation platform incorporating visualization, data logging, and automated testing was developed to systematically evaluate the complete fuzzy rule base. Simulation results from all 81 fuzzy-rule combinations show that the motor PWM adapts to variations in speed error, while the fan PWM is prioritized under elevated temperature conditions to enhance thermal safety. Overlapping membership functions produce smooth intermediate PWM outputs, whereas the discrete PWM-to-RPM mapping results in stepwise speed variations. Overall, the proposed controller demonstrates stable and adaptive speed and thermal control behavior in simulation and provides a practical foundation for future real-time hardware implementation and quantitative experimental validation.

A Review Study of Influencing Factors and Conceptual Scaling Framework for Spray Drying Assisted by Ultrasonic Vibrating Mesh Atomizers

Agustriputra IDG — 2026-07-31

Abstract. Spray drying is widely used in the pharmaceutical, food, and chemical industries for converting liquid feed into dry particulate products. However, conventional spray drying systems commonly generate broad droplet size distributions and exhibit limited capability for producing submicron particles. To overcome these limitations, ultrasonic vibrating mesh atomizers have recently attracted significant attention due to their ability to generate highly uniform droplets with relatively low energy consumption and improved atomization controllability. Previous studies have investigated the influence of individual operating parameters on ultrasonic spray drying performance, particularly using laboratory-scale systems such as the Büchi Nano Spray Dryer B-90. Nevertheless, existing literature remains fragmented, with limited efforts to systematically establish the relative importance of governing parameters or to develop a unified conceptual framework for scaling ultrasonic spray drying systems from laboratory to industrial applications. This study addresses this gap by conducting a systematic literature-based parametric analysis of spray drying systems assisted by piezoelectric vibrating mesh atomizers. Experimental studies employing the Büchi Nano Spray Dryer B-90 were critically reviewed to identify the dominant factors controlling droplet formation, atomization stability, and particle generation behaviour. The analysed parameters were classified into three principal categories: atomization parameters, fluid properties, and drying process parameters. The analysis demonstrates that mesh aperture size, ultrasonic vibration frequency, and spray throughput are the primary parameters governing droplet formation and particle size distribution. Fluid properties, including viscosity, surface tension, and feed concentration, strongly influence atomization stability through their effects on dimensionless parameters such as the Weber number and Ohnesorge number. In contrast, drying parameters, including inlet air temperature and gas flow rate, predominantly affect evaporation kinetics and particle morphology rather than the initial droplet generation process. The reviewed studies further indicate that ultrasonic atomization commonly operates within a regime characterized by moderate Weber numbers and relatively low Ohnesorge numbers, consistent with capillary wave breakup mechanisms. Based on these findings, a conceptual scaling framework is proposed in which atomization similarity, fluid dynamic similarity, and drying conditions must be simultaneously considered to achieve reliable scale-up of ultrasonic spray drying systems

Performance Evaluation of Banana Fiber as a Natural Adsorbent for Methane Enhancement in Biogas Using GC–MS Analysis

I Wayan Sutama — 2026-07-31

Biogas utilization from agricultural waste in Indonesia remains underdeveloped despite its significant potential as a renewable energy source. Biogas produced through anaerobic digestion contains a high concentration of carbon dioxide (CO₂), which lowers its calorific value and limits its direct use as a clean fuel. Therefore, biogas upgrading is necessary to increase methane (CH₄) concentration and improve fuel quality. This study evaluates the performance of banana fiber as a natural adsorbent for methane enhancement and carbon dioxide removal in biogas. Banana fiber was selected because of its lignocellulosic composition and porous structure, which provide potential adsorption sites for gas molecules. The experimental setup employed a fixed-bed filtration system in which raw biogas from an anaerobic digester was passed through a column packed with untreated banana fiber. Gas samples were collected before and after filtration and analyzed using Gas Chromatography–Mass Spectrometry (GC–MS) to determine changes in CH₄ and CO₂ concentrations. The results showed that methane concentration increased from 51.37% to 60.84%, corresponding to an enhancement of 9.47%, while carbon dioxide concentration decreased from 48.63% to 39.15%, representing a reduction of 9.48%. These findings indicate that banana fiber effectively improves biogas quality by selectively adsorbing CO₂ and enriching methane content. The adsorption performance is attributed to the presence of hydroxyl (–OH) and carboxyl (–COOH) functional groups in the lignocellulosic structure of banana fiber, which facilitate physical adsorption and enhance gas–solid interactions. In addition, the porous structure of the fiber increases surface area and supports adsorption efficiency. This study demonstrates the effectiveness of untreated banana fiber as a low-cost and environmentally friendly adsorbent for biogas upgrading using GC–MS analysis. The findings highlight its potential application in small-scale and decentralized renewable energy systems, particularly in rural and agricultural areas. Furthermore, the study provides important implications for laboratory-scale biogas purification systems and future industrial biogas upgrading applications.

Numerical Analysis of Outlet Number Effects on Temperature Distribution in a Briquette Oven Using CFD

Alviani Hesthi Permata Ningtyas — 2026-07-31

The performance of briquette drying systems is strongly influenced by airflow distribution and thermal uniformity within the drying chamber, which are governed by outlet configuration and internal flow patterns. However, limited studies have systematically quantified the effect of exhaust outlet arrangements on the coupled heat transfer and fluid flow behavior in industrial-scale briquette ovens. This study aims to numerically investigate the influence of single-, double-, and four-outlet configurations on airflow characteristics, temperature distribution, and overall thermal performance of a briquette drying oven. A three-dimensional geometric model representing the combustion chamber, drying chamber, and briquette racks was developed and analyzed using Computational Fluid Dynamics (CFD). Steady-state simulations were performed in ANSYS Fluent employing the standard k–ε turbulence model, with air properties, inlet velocity (9.97 m/s), and thermal boundary conditions defined based on operational data. The results reveal that outlet configuration significantly affects flow recirculation intensity and temperature uniformity across the briquette racks. The four-outlet configuration produced the most homogeneous airflow distribution and reduced thermal gradients, thereby enhancing convective heat transfer effectiveness compared to single- and double-outlet designs. Conversely, the single-outlet case exhibited pronounced recirculation zones and localized temperature variations, potentially leading to uneven drying. These findings demonstrate that optimizing outlet arrangement is a critical design parameter for improving drying efficiency and energy utilization in briquette oven systems, providing a validated numerical framework for future thermal system optimization.

Analysis of Spray Droplet Nozzle Characteristics on Biodiesel (B35) with Injection Pressure Variations

Syaifularif — 2026-07-31

This study, entitled Analysis of Spray Droplet Characteristics of Nozzle in Biodiesel (B35) under Injection Pressure Variations, investigates the effect of injection pressure on the spray droplet atomization characteristics of Biodiesel B35 and correlates these characteristics with changes in fuel molecular composition determined using Gas Chromatography–Mass Spectrometry (GC–MS). The novelty of this research lies in integrating spray atomization analysis with GC–MS-based molecular characterization to explain how molecular composition influences fuel atomization behavior. An experimental approach was employed using several injection pressure variations in a nozzle system, followed by GC–MS analysis of Diesel B0, Biodiesel B35, and the B0+B35 blend. The GC–MS results revealed that the blended fuel exhibited a broad molecular weight distribution ranging from 106.165 to 843.6107 g/mol, containing both light hydrocarbons, such as O-xylene (C₈H₁₀), and heavy hydrocarbons, such as hexacontane (C₆₀H₁₂₂). Biodiesel B35 showed the highest average molecular weight due to the predominance of fatty acid methyl ester (FAME) compounds, whereas Diesel B0 exhibited the lowest molecular weight because of its higher proportion of light hydrocarbon fractions. The blending process also resulted in stable, reduced, disappeared, and newly formed molecular species, indicating changes in molecular distribution caused by physical interactions between the fuels. These compositional changes affected key fuel properties, including viscosity, volatility, and atomization performance. Spray image analysis demonstrated that increasing injection pressure produced finer and more uniformly distributed droplets, indicating improved atomization quality. The findings demonstrate that the interaction between fuel molecular characteristics and injection pressure plays a significant role in determining spray behavior and has the potential to improve diesel engine combustion efficiency and fuel performance.