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The problem lies in the inconsistent quality of M10 hexagonal head bolts with a spacing of 1.5 mm, a bolt length of 100 mm and slow production speed for manual production. The purpose of the analysis is to obtain consistent, standard, and productive quality of M10 hexagonal head bolts with a spacing of 1.5 mm, a bolt length of 100 mm. The analysis method includes the selection of AISI 1040 raw materials with a diameter of 10 mm in the form of rolls, the determination of the production process through raw material inspection, diameter reduction from 10 mm to 9.8 mm, the formation of hexagonal heads with a machine, cutting the length of the bolts and the bolt end chamfer, making M10 threads with a range of 1.5 mm with a machine, hardening, 10 m thick Zinc coating, thread profile inspection, sample hardness test, and sample tensile test. The results of mass production with the machine obtained a hexagonal head bolt with a thread size of M10x1.5 mm, a bolt length of 100 mm, a capacity of 500 units/hour in accordance with the ISO 9001:2015 standard with a hardness of 30 HRC and a tensile strength of 830 MPa at a cost of Rp. 1133/bolt and a process duration of 8.3 minutes/bolt which implies that product quality can be more guaranteed to be consistent and uniform.

Brake discs are one of the motorcycle spare parts that function to connect and reduce speed when the motorbike is moving, although very simple, this spare part is part of the braking system and has a very important role, without braking it will endanger the driver and other road users. To determine the hardness of the motorcycle brake disc on two original brake discs and variation brake discs on the Yamaha Vision sport motorbike by conducting Rockwell hardness tests on the original and variation brake discs with 10 test variable points. The results obtained for the average value at the level of hardness on the original disc sample are 55.1 HRC and the average value on the variation disc sample is 44.6 HRC, and the conversion hardness value from the Rockwell test. For Brinell testing and tensile testing from the results of Rockwell hardness testing, the average Brinell and tensile test values ​​were converted from the test site with the average Brinell conversion results for the original disc being 575 HBS, while the average variation disc value was 417.1 HBS, the conversion tensile test value with the results on the original disc was 1626 N/mm² and the variation disc was 1427 N/mm² with 10 variable point Rockwell testing and the conversion value of the Brinell hardness test and the original disc tensile test value was still greater than the variation disc tensile test value.

Mochi is a cake made from glutinous rice flour with other ingredients and then steamed. White sweet potato flour is used as a substitute because it contains high levels of fiber, with the addition of elephant ginger extract, which is expected to be able to neutralize the unpleasant taste and scent of white sweet potato flour. The aim of this study was to determine the right formulation in order to obtain white sweet potato flour substitution mochi and a high concentration of elephant ginger extract. This study used a completely randomized design (CRD), which consisted of two factors, namely the concentration of glutinous rice flour and white sweet potato flour (90:10, 80:20, and 70:30) and the percentage of elephant ginger extract (to 100 ml of water) (1.5%, 3%, and 4.5%). The best results of the chemical analysis were white sweet potato flour 30 g and ginger extract 4.5%, with a moisture content of 23.66%, an ash content of 0.25%, a total sugar content of 7.64%, and fiber of 2.60%. Based on the results of the physical analysis, the colour L*47.62 (bright brown), a* -4.68 (slightly green), b* 12.20 (yellowish) and a hardness value of 8.90 N, gumminess of 6.27 N, chewiness of 1.73 N, cohesiveness of 0.71 N, and adhesiveness of 1.17 N. Mochi with white sweet potato flour substitution and concentration of elephant ginger extract can be a nutritions food and a source of fiber.

The demand for lightweight materials with high mechanical strength has driven the development of aluminum alloys, particularly Al-Mg-Si, through deformation processes such as cold rolling. This study aims to analyze the effect of varying degrees of cold rolling deformation on the grain aspect ratio and macrohardness of homogenized Al-Mg-Si alloys. Deformation was applied at three thickness reduction levels—5%, 10%, and 20%—followed by microstructural characterization using optical microscopy and macrohardness testing in accordance with ASTM E-18 standards. The results show that increasing deformation levels lead to elongated grain morphology, with the grain aspect ratio rising from 1.16 to 2.07 and macrohardness increasing from 46.64 HRE to 62 HRE. The emergence of slip lines and grain flattening indicates the occurrence of intense plastic deformation, while work hardening results from dislocation accumulation that impedes further slip motion. These findings confirm a strong correlation between microstructural evolution and mechanical property enhancement in cold-deformed Al-Mg-Si alloys. This research contributes to the optimization of cold rolling parameters to produce engineering materials with a desirable balance of strength, formability, and fatigue resistance for applications in the mining and heavy manufacturing industries.

The manufacturing industry in Indonesia has experienced significant growth. This increase has also impacted the demand for motorcycle spare parts. Currently, brake pads are composed of asbestos, which makes them prone to overheating and failure when reaching high friction temperatures. Therefore, an alternative brake pad material is an organic material mixed with coconut shell powder and bamboo fiber. This study aims to analyze the wear and hardness levels of motorcycle brake pads made from coconut shell powder and bamboo fiber. The study used varying ratios of coconut shell powder, bamboo fiber, and epoxy resin: 40:30:30, 35:35:30, and 30:40:30. Eighteen specimens were tested. Wear testing was performed using an Ogoshi Wear Tester, while hardness testing was performed using a Brinell hardness tester. The test results showed that the smallest wear rate on brake pads with variations of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin was 0.001107984 mm3/kg.m. The highest hardness level was also in the variation of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin at 63,0024 kg/. So it can be concluded that the greater the percentage of coconut shell powder and the smaller the percentage of bamboo fiber, the lower the wear rate. If the greater the percentage of coconut shell powder and the smaller the percentage of bamboo fiber, the higher the hardness level. So it can be concluded that a good brake pad variation is a variation of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin.

The manufacturing industry in Indonesia has experienced significant growth. This increase has also impacted the demand for motorcycle spare parts. Currently, brake pads are composed of asbestos, which makes them prone to overheating and failure when reaching high friction temperatures. Therefore, an alternative brake pad material is an organic material mixed with coconut shell powder and bamboo fiber. This study aims to analyze the wear and hardness levels of motorcycle brake pads made from coconut shell powder and bamboo fiber. The study used varying ratios of coconut shell powder, bamboo fiber, and epoxy resin: 40:30:30, 35:35:30, and 30:40:30. Eighteen specimens were tested. Wear testing was performed using an Ogoshi Wear Tester, while hardness testing was performed using a Brinell hardness tester. The test results showed that the smallest wear rate on brake pads with variations of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin was 0.001107984 mm3/kg.m. The highest hardness level was also in the variation of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin at 63,0024 kg/. So it can be concluded that the greater the percentage of coconut shell powder and the smaller the percentage of bamboo fiber, the lower the wear rate. If the greater the percentage of coconut shell powder and the smaller the percentage of bamboo fiber, the higher the hardness level. So it can be concluded that a good brake pad variation is a variation of 40% coconut shell powder, 30% bamboo fiber and 30% epoxy resin.

Al–Mg–Si aluminum alloys are widely utilized in engineering applications due to their low density, excellent corrosion resistance, and mechanical properties that can be modified through heat treatment. This study investigates the effect of homogenization on the microstructure and hardness of Al–Mg–Si alloys produced by the squeeze casting process. The experimental procedure involved alloy melting, squeeze casting at 76 MPa using preheated metal molds, followed by homogenization at 400 °C for 4 hours. Microstructural characterization was performed using optical microscopy to examine the dendritic morphology and measure the secondary dendrite arm spacing (SDAS). Mechanical properties were evaluated through Vickers microhardness and Rockwell macrohardness testing. The results show that homogenization increases the SDAS from 32.59 μm to 36.88 μm and decreases the volume fraction of interdendritic phases from 15.51% to 13.57%. Furthermore, microhardness decreased from 50.22 VHN to 38.58 VHN, while macrohardness decreased from 54.60 HRE to 46.64 HRE. These reductions are attributed to the partial dissolution of Mg₂Si precipitates into the aluminum matrix during homogenization. Overall, this research provides valuable insight into the optimization of initial heat treatment parameters for Al–Mg–Si alloys produced by squeeze casting. The findings highlight the role of homogenization in improving microstructural uniformity and preparing the alloy for subsequent deformation processes such as cold rolling and extrusion, particularly for structural components used in mining and heavy transportation industries.

This study aims to determine the effect of varying hybrid composite volume fractions of luffa (Luffa cylindrica) fiber and fiberglass on the tensile strength of the material. The composite matrix used was polyester resin, while the reinforcements consisted of luffa fibers treated with 5% KOH alkaline solution to improve adhesion with the matrix, and fiberglass as an additional strengthening material. The composition variations applied in this research were 90%:5%:5%, 85%:7.5%:7.5%, and 80%:10%:10% (polyester resin : luffa fiber : fiberglass). The fabrication process was carried out using the hand lay-up method, which is widely used for producing layered composites, followed by tensile testing according to standard mechanical testing procedures to evaluate tensile strength and elongation. The results showed that the addition of luffa fiber and fiberglass fractions had a significant influence on the mechanical properties of the composites. The 80%:10%:10% variation demonstrated the highest tensile strength value of 13.65 MPa and the highest elongation of 0.0105%, indicating better mechanical performance compared to other variations. These findings confirm that the hybridization of natural luffa fiber and synthetic fiberglass can work synergistically to improve the tensile strength of the composite. However, higher fiber fractions should be considered carefully, as they may affect the homogeneity of the mixture and the quality of interfacial bonding. Further research is recommended to optimize volume fractions, enhance fiber surface treatments, and evaluate additional mechanical properties such as impact strength and hardness, in order to explore the potential of hybrid composites as eco-friendly materials with promising mechanical performance.

This study investigates the corrosion inhibition potential of a newly synthesized organic compound, (E)-4-hydroxy-3-(phenylamino)pent-3-en-2-one (LASA3), using computational chemistry approaches. Density Functional Theory (DFT) calculations were performed at the B3LYP/6-31G(d) level of theory with the Gaussian09 software package to evaluate several key quantum chemical parameters. These parameters include total energy, the energies of the highest occupied molecular orbital (EHOMO) and lowest unoccupied molecular orbital (ELUMO), the energy gap (ΔEgap), dipole moment, chemical hardness, softness (σ), and the number of electrons transferred (ΔN). The computational results reveal that LASA3 exhibits a higher EHOMO value and a smaller ΔEgap compared to its precursor molecules, referred to as S.M.1 and S.M.2. A higher EHOMO value suggests that LASA3 has a greater electron-donating ability, which enhances its interaction with the metal surface. Likewise, the reduced ΔEgap indicates greater chemical reactivity and a higher likelihood of forming stable coordination bonds with iron atoms on the carbon steel surface. Electrostatic potential (ESP) map analysis further supports these findings by highlighting the distribution of electron density within the LASA3 molecule. The ESP maps show significant electron-rich regions localized around nitrogen and oxygen atoms, which are potential active sites for adsorption onto the steel surface. This adsorption process plays a crucial role in blocking active corrosion sites and reducing the rate of metal degradation. In conclusion, the theoretical analysis confirms that LASA3 has superior electronic properties for corrosion inhibition compared to its starting materials, S.M.1 and S.M.2. Its ability to donate electrons, favorable dipole characteristics, and strategically located electron-rich sites make it a promising candidate for further experimental evaluation as an efficient corrosion inhibitor for carbon steel applications.  

Welding is one of the most essential metal joining processes in manufacturing, construction, and industrial applications, where Shielded Metal Arc Welding (SMAW) remains widely used due to its flexibility, cost-effectiveness, and ability to be applied in various welding positions. This study aims to analyze the effect of welding position variations on the mechanical properties of SS400 steel, particularly in terms of tensile strength, bending strength, and microstructural characteristics. The experimental method was conducted using 6 mm thick SS400 steel with E6013 electrodes of 2.6 mm diameter in three welding positions: 1G, 2G, and 3G. The welded specimens were then tested through tensile testing (ASTM E8) and bending testing (ASTM E190-14), followed by microstructural analysis in the weld metal area. The results revealed that welding position significantly affects the mechanical properties of welded joints, where the 3G position produced the highest tensile strength of 188.48 kgf/mm², while the 2G position produced the lowest tensile strength of 113.70 kgf/mm². Conversely, the bending test showed that the 2G position provided the maximum bending strength of 1394 kgf/mm², followed by 3G and 1G positions. Microstructural observations demonstrated variations in the distribution of ferrite, pearlite, martensite, and cementite phases across different welding positions, with the dominance of ferrite and pearlite in the 3G specimen contributing to higher tensile strength, while the dominance of martensite and cementite in the 2G specimen enhanced hardness and bending resistance. Overall, this study confirms that welding position plays a crucial role in determining the quality of SS400 welded joints, and the findings are expected to serve as practical guidance for industry in selecting appropriate welding positions for construction needs, while encouraging further research with additional variables such as electrode type, welding current, and post-weld heat treatment to achieve a more comprehensive understanding.

Compressive strength is one of the mechanical properties of rock behavior. This study focuses on the Balikpapan and Kampungbaru Formations located in the Kutai Kartanegara area, East Kalimantan. The Schmidt Hammer testing method was applied due to the lack of previous studies utilizing this tool to evaluate rock hardness in correlation with compressive strength. The research site is situated in the Kutai Kartanegara area, specifically in the districts of Muara Badak, Muara Jawa, and Sanga-Sanga. Field observations revealed the presence of claystone slopes at predetermined locations. Based on the test results, the uniaxial compressive strength (UCS) values for the Balikpapan Formation range from 3.453 MPa to 5.454 MPa, while the Kampungbaru Formation ranges from 3.317 MPa to 8.571 MPa. The Schmidt Hammer rebound number (RN) values for the Balikpapan Formation range from 17 to 19.6, and for the Kampungbaru Formation from 15 to 23.7. A negative correlation was found between the rebound number and UCS, where higher RN values tend to correspond with lower UCS values. This is supported by the linear regression analysis showing a negative coefficient (-0.450).  

Spring steel is one type of material that is widely used in various engineering applications, such as vehicle suspension systems and equipment that require resistance to dynamic loads. Spring steel possesses various mechanical characteristics that are strongly influenced by the microstructure of the material. These characteristics remain consistently affected throughout the entire material. Heating that occurs due to exposure to flame can alter certain microstructural properties of spring steel and affect its performance. In this study, an analysis was carried out on all changes in the microstructure of spring steel caused by flame heating, as well as its effect on the hardness of the material. The results of the study showed that heating can indeed cause changes in the microstructural phase and a decrease in fatigue resistance of the spring steel.

The manufacturing industry continues to develop quality to improve productivity and business sustainability. One method commonly used in metal surface treatment is the anodizing process. One of these industries is the electroplating industry which uses chemicals as aluminum dyes that damage the environment. The purpose of this study is to determine the effect of using natural dyes turmeric, dragon fruit, and pandan leaves as coloring materials in the anodizing process of bicycle components on their hardness. The specimen used in this study is 1100 aluminum. The results showed that the highest hardness value using dragon fruit natural dye was 204.775 VHN.

This study analyzes the use of safety harnesses in ensuring workplace safety at PT. XYZ, focusing on their role in preventing accidents during high-altitude work. The research employs the Job Safety Analysis (JSA) method to identify potential hazards and evaluate risk control measures. Data from 2021 to 2024 reveal a significant correlation workplace accidents with injuries ranging from minor to severe. The findings underscore the importance of strict adherence to safety regulations, proper training, and routine equipment inspections. The study concludes that consistent use of safety harnesses, aligned with national and industry standards, can significantly reduce accident rates and enhance worker safety.

This study examines the depiction of women’s struggles in the novel Perempuan yang Menunggu di Lorong Menuju Laut by Dian Purnomo using Françoise d’Eaubonne’s ecofeminism perspective. The novel highlights a strong connection between women and nature, both of which are subjected to oppression within a patriarchal social structure. The core issue discussed in this research is how female characters in the story respond to various forms of injustice—social, cultural, and ecological—and how the text constructs a parallel between the exploitation of women and the degradation of nature. The purpose of this study is to identify and analyze the forms of resistance expressed by the female characters against gender-based oppression and environmental damage. In addition, the research aims to demonstrate how ecofeminism serves as a critical framework to expose and challenge patriarchal dominance through literature. This research applies a descriptive qualitative method with content analysis. Data were gathered using reading and note-taking techniques, then interpreted based on De’Eaubonne’s ecofeminist theory. The results reveal that women in the novel resist domination through various actions, such as speaking out against injustice, rejecting violence, and raising environmental awareness. Their resistance is portrayed not just as personal defiance but as a collective effort rooted in ecological consciousness. The novel, therefore, becomes a medium that challenges patriarchal norms while proposing a more balanced relationship between humans and nature. In conclusion, this study affirms literature’s role as a powerful tool to voice socio-environmental concerns and promote the empowerment of women as agents of change.

Aloe vera gel contains antioxidative phenolic compounds. Fresh aloe vera gel is less accepted by the community due to its bitter taste from its latex. An acceptable alternative to aloe vera products is an aloe vera gel beverage because people of all ages currently favor light drinks. This study aims to produce aloe vera gel beverages with high antioxidant content by varying the gel size and boiling duration for easy consumption and preference by panelists. This research employed a completely randomized design (CRD) with two treatment factors, namely variations in gel size (0.5x1 cm, 1x2 cm, 2x3 cm) and boiling duration (10 minutes, 15 minutes, 20 minutes). The obtained data were subsequently analyzed Analysis of Variance (ANOVA). If differences were found, Duncan's Multiple Range Test (DMRT) was conducted at a significance level of 5%. The research results indicate that variations in gel size and boiling duration affect antioxidant activity, moisture content, total sugar content, gel texture, and preference level. The acceptable aloe vera gel beverage, preferred by the panelists which made with a gel size of 0.5x1 cm and a boiling duration of 10 minutes, with exhibited the highest antioxidant activity 6.72% RSA, moisture content 94.15%, total sugar content 13.35%, hardness (6.25 g/cm2, and deformation 2.81 mm.

Leaf springs are one of the suspension systems that are still widely used in various modes of transport such as cars and trucks. The spring functions to support the load and reduce vibration from operational activities. This study aims to analyse the bending strength and hardness of steel leaf springs of trucks and cars resulting from tempering heat treatment. The three point bending method was used as the flexural strength testing method and the Rockwell C Hardness method testing was used for hardness testing with leaf springs in raw, tempered 460°C, and tempered 510°C conditions. From the results of the study, the highest average bending strength value of 3733,55 MPa was obtained and an average roughness value of 31,8 HR was obtained for the 510°C tempered truck leaf springs. This also applies to the 510°C tempered car leaf springs, where the average bending strength value obtained is 3392,65 MPa and the average hardness value obtained is 29,5 HR. Thus, it is recommended that tempering heat treatment that can be applied to truck and car leaf springs be carried out at 510°C to increase the bending strength and ductility of the leaf springs.