PENGARUH PERLAKUAN PANAS CASE HARDENING PADA ALUMINIUM PADUAN SERI 7075 TERHADAP SIFAT MEKANIK DAN STRUKTUR MIKRO

THE EFFECT OF CASE HARDENING TREATMENT ON ALUMINUM 7075 TOWARD ITS MECHANICAL PROPERTIES AND MICRO STRUCTURE Febri Budi Darsono Mechanical Engineering Department Faculty of Engineering, Sebelas Maret University Surakarta 57126, Indonesia Email: [email protected] Abstract This research was aimed at figuring out the effect of case hardening treatment on aluminum 7075 toward its mechanical properties and micro structure. Pack carburizing was the method used in this process. It was conducted in 2 hours of holding time in various solution heat treatment (SHT): 3500C, 4000C, 4500C, and 5000 C using smoergen oven, which was then followed by quenching. Several tests to see the effect of the treatment were done before and after the treatment, namely: Vickers hardness test using HWMMT-X7, tensile test ASTM B557-84 using SANS UTM, micro and macro structure test, XRD test using Rigaku Benchtop, and SEM-EDS test using JEOL JSM-6510 LA. The result showed that the hardness and tensile of aluminum 7075 before treatment were 59.1 VHN and 235.7 Mpa. After the treatment was given, its hardness values were 94.0, 120.7, 141.3, and 145.9 VHN. The tensile strengths were 321.7, 410.0, 480.0, and 538.3 Mpa. Micro structure formed on case hardening treatment, such as phase Al-Fe-Cu, Mg2Si, and CuAl2. The result showed that SHT temperature rise in pack carburizing process increased the tensile strength, while the increase of the hardness value is due to the formation of Al4C3 phase on the aluminum surface. Different of micro structure formed on SHT 3500C and 5000C, grain boundary area (Mg2Si) on SHT 3500C smaller than SHT 5000C. Keywords: Aluminum 7075, SHT, Pack Carburizing, XRD, SEM-ED

Pengendalian Banjir Kawasan Simpang Lima Semarang

Simpang Lima area of Semarang is administration region, education residence, service, and industry which are constructed in the center of Semarang sub district. Center Semarang region is an area where is topographically flat. Industry development, trade, and rapid growth people bring Simpang Lima are of Semarang as the prominent center growth of Semarang city. In addition flood happened in region of Simpang Lima area of Semarang is caused by the lack of drainage performance, high sedimentation, and not yet maximum in flood control using provision of water pumps. There are some scenarios to solve that proble,. the first scenario is by fixing the channels in Simpang Lima are of Semarang in order to increase the capacity of channel flow. This way includes widening the channel, fixing the slope of bottom channel, and scanting the discourtesy of channel flow wall. Second scenario is by making new channel in Simpang Lima cycle, because of the difficult to rehabilitate the existing channel which locates under sidewalk of Simpang Lima cycle, so taken solution to make new channel. The new channel locates under the road of Simpang Lima cycle and uses closed channel type. The third scenario is by maximizing the capacity in Kartini Pump Station. Hope by maximizing the capacity of pump may fasten the process of water disposal from Kampung Kali River to Banjir Kanal Timur River and reduce water level in Simpang Lima area of Semarang drainage channel downstream section

Studi Modifikasi Geometri Sudu pada Turbin Air Propeller Menggunakan Metode Elemen Hingga

Desain kekuatan turbin air propeller berdasarkan ketahanan terhadap pembebanan gaya aksial dari air. Pembebanan gaya aksial pada turbin air propeller menyebabkan tegangan bending pada sudu dan berpotensi terjadi kegagalan sudu pada struktur turbin. Tujuan dari penelitian ini untuk membandingkan kekuatan modifikasi desain geometri turbin air propeller, yaitu penambahan fillet pada sisi hub sudu dan penambahan ketebalan sudu. Pengambilan data penelitian ini dengan Metode Elemen Hingga menggunakan Solid Works Simulation 2016 dan pembebanan pada sudu dengan tekanan statik. Hasil akhir penelitian ini menunjukkan bahwa modifikasi desain geometris dengan penambahan ketebalan sudu lebih meningkatkan faktor keamanan dibandingkan penambahan fillet pada sisi hub sudu

TINJAUAN LITERATUR: PENINGKATAN KETAHANAN API DAN SIFAT MEKANIK PADA KOMPOSIT POLIMER DENGAN PENAMBAHAN BAHAN LIMBAH GEOPOLIMER

Composite polymers are now under development and are widely used in automobile manufacturing for interior panels, door panels, and bodywork. The research and development of polymer composites for the automobile manufacturing must have resilient fire resistance requirements. Currently, polymer composites with fire resistance capabilities have been developed with geopolymer materials, which offer benefits and produce excellent performance. Geopolymers are inorganic polymers that contain aluminosilicates, silica oxides, and alumina oxides. They have thermally resistant mechanical characteristics. Geopolymer materials are commonly derived from waste materials, including those utilized as additions to polymer composite materials, specifically coal fly ash and clay-based waste. The purpose of this literature is to discuss the path and progress of waste-based polymer reinforced composite technology for fire resistance. The methodology employed in this study takes a conceptual approach to articles on the influence of adding different types of geopolymer materials on the fire resistance properties of natural fiber reinforced composites. According to the findings, articles involving the inclusion of geopolymer materials tend to lower resistance to tensile and flexural stresses, whilst the addition of this geopolymer material reduces fire resistant qualities

Sosialisai Kendaraan Listrik Berbasis Baterai (KLBB) bagi driver online

Abstrak Penggunaan kendaraan listrik merupakan salah satu solusi untuk menekan peningkatan polusi udara yang disebabkan oleh emisi karbon khususnya yang terjadi di kota-kota besar Indonesia. Berdasarkan observasi lapangan maka perlu diadakan kegiatan Edukasi dan Sosialisasi Penerapan Kendaraan Listrik Berbasis Baterai Bagi Driver Online di Kota Semarang Dalam Upaya Green Energy Transportation. Metode yang digunakan adalah penerapan secara langsung. Fokus kegiatan ini adalah: (1) Aspek Pengetahuan Kendaraan Listrik Berbasis Baterai, (2) Aspek Perawatan Kendaraan Listrik Berbasis Baterai: meliputi pelatihan perawatan berkala pada Kendaraan listrik Berbasis Baterai. Terselenggaranya Kegiatan Pengabdian Edukasi dan Sosialisasi Penerapan Kendaraan Listrik Berbasis Baterai Bagi Driver Online di Kota Semarang Dalam Upaya Green Energy Transportation. Fokus pengabdian pada pengetahuan driver online terkait pengetahuan dasar sistem kendaraan listrik. Kata kunci: driver online; kendaraan listrik; sosialisasi Abstract Using electric vehicles is one of the solutions to reduce the increase in air pollution caused by carbon emissions, especially in big cities in Indonesia. Based on field observations, it is necessary to hold an Education and Socialisation activity on the Application of Battery-Based Electric Vehicles for Online Drivers in Semarang City to Green Energy Transportation. The method used is direct application. The focus of this activity is (1) Knowledge aspects of battery-based electric vehicles, (2) Maintenance aspects of battery-based electric vehicles, including periodic maintenance training on battery-based electric vehicles. It was implementing Education and Socialisation of Battery-Based Electric Vehicle Implementation for Online Drivers in Semarang City to Green Energy Transportation. The service focuses on the knowledge of online drivers related to basic knowledge of electric vehicle systems. Keywords: online driver; electric vehicle; socialisatio

Kekuatan Bending dan Tarik Komposit Berpenguat Serat Eceng Gondok/Tebu Bermatrik Epoxy

The use of natural fiber as composite material is growing rapidly due to excellent characteristics, environmentally friendly quality and low price. For this reason, natural fiber breaks the dominance of synthetic fiber composite previously used in industries, especially in automotive manufacturing. The purpose of this study is to determine the effect of fiber orientation on the flexural and tensile strength of water hyacinth-sugarcane fiber composite with epoxy matrix. The composite then be tested as an alternative to doortrim. Fiber orientation applied to specimens was random for sugarcane fiber, but continuous on water hyacinth fiber with angle variants of -45/45, 45/90, 45/45, and 90/90. Specimen standard for flexural test is ASTM D790-15 and ASTM D638-14 for tensile test. The study results show that the highest average value for flexural strength is 51.7 MPa of the 45/90 variant, while the lowest average value of 16.6 MPa is the 45/45 variant. Both 45/90 and -45/45 variants have the highest tensile strength of 30 MPa. The 90/90 variant records the weakest tensil strength value of 20 MPa. The highest flexural and tensile strength values exceed minimum score of the SNI 01-4449-2006 and equal the values of panel assy backdoortrim. This experiment proves that fiber orientation affects mechanical properties of composite materials, especially in terms of flexural or tensile strength

PENGEMBANGAN YOUNG TECHNOPRENEUR UNNES MELALUI PENGELOLAAN USAHA BERBASIS DIGITAL ENTREPRENEUR

ABSTRAKDalam upaya menciptakan wirausaha baru mandiri yang berbasis iptek maka perlu bagi tenant menguasai aspek digital entrepreneur dalam pengelolaan usaha dan pemasaran berbasis digital. Tujuan dari kegiatan ini adalah memberikan pelatihan kepada tenant dalam pemasaran produk barang/jasa sesuai dengan usaha yang dijalankan berbasis digital. Metode yang digunakan dalam pengabdian ini adalah penerapan secara langsung dengan tahapan persiapan, analisa permasalahan, Pelatihan dalam implementasi digital entrepreneurship, Pendampingan dalam mengelola modal usah, dan Evaluasi pelaksanaan kegiatan. Kegiatan pengabdian terlaksana dengan dihadiri oleh 3 tenan dan mahasiswa yang berminat wirausaha yang berjumlah 14 orang. Materi yang disampaikan terkait pengembangan usaha melalui media digital Instagram. Optimalisasi penggunaan media digital pada era digital sangat diperlukan branding, selling, dan sharing. Pendampingan dilakukan untuk dalam pengelolaan usaha berbasis digital melalui Instagram. Hasil menunjukan terdapat peningkatan follower yang signifikan setelah tenan mengikuti kegiatan yakni sebesar 70,4% pada MDPL, 100% pada F Project, dan 72,4% pada Bengkel Autoscar. Selain itu, bagi mahasiswa yang sebelumnya tidak memiliki minat usaha setelah mengikuti kegiatan ini muncul ide untuk membuka usaha. Kata kunci: digital entrepreneur; wirausaha; usaha; technopreneur; media ABSTRACTTo create new independent entrepreneurs based on science and technology, tenants must master digital entrepreneur aspects in managing digital-based business and marketing. The solutions offered in this service are, first, the application of science and technology in digital-based business management. Second, tenant assistance training in marketing goods/services by the business being run. With this dedication, it is hoped to increase productivity and business development for MDPL Farm tenants, Unnes Machine Visit Service Workshop (F Project), and Autoscar Workshop. The method used in this service is direct application with the preparation stage, problem analysis, training in the implementation of digital entrepreneurship, assistance in managing venture capital, and evaluating the implementation of activities. The dedication activity was carried out in the presence of 3 tenants and students interested in entrepreneurship, totaling 14 people. The material presented is related to business development through Instagram digital media. Optimizing the use of digital media in the digital era needs branding, selling, and sharing. Assistance is provided for managing digital-based businesses through Instagram. The results showed a significant increase in followers after participating in the activity, namely 70.4% at the MDPL, 100% at the F Project, and 72.4% at the Autoscar Workshop. In addition, students who previously had no business interest after participating in this activity came up with the idea to open a business. Keywords: digital entrepreneur; entrepreneur; business; technopreneur; medi

Visual Inspection and Non-Destructive Test (NDT) on ASTM A36 Welded Joints Produced by GMAW

Low-carbon steel is often used for welding joints, whether in the form of structural steel or other materials; the application of this material is used in shipbuilding, bridge construction, and other fields. Welding inspection is needed to determine the quality of the weld. Visual inspection and non-destructive testing (NDT) are techniques in welding inspection. This study aims to determine the results of visual inspection and non-destructive testing (NDT) on welding joints of low-carbon steel produced by GMAW. The welding joints used are V-butt joints with a bevel angle of 300, 10 mm thick plate, 2.6 mm root gap, variations in welding layers: 3 layers (root pass, filler pass, and capping), and 4 layers (root pass, 2 filler passes, and capping), filler metal ER 70S-6 0.8 mm, and CO2. Volts, current, travel distance, and shielding gas flow rate are welding parameters. The tests carried out were visual inspection referring to limits for imperfections in ISO 6520-1, non-destructive tests (NDT) that were carried out, namely penetrant tests and radiography tests. The visual inspection and non-destructive testing (NDT) on specimen 1 reveal an internal defect, specifically a lack of fusion; the specimen should be rejected. Specimen 2 shows an imperfection in the surface area, namely in the form of spatter (2 spots), and there are internal imperfections in the form of porosities with an area of less than 3%. The specimen should be accepted.

Peningkatan kualitas hasil pengecatan melalui penerapan mesin rotary polisher di bengkel Yunex Paint desa Gesing Temanggung

Abstrak Tingginya jumlah penjualan kendaraan bermotor di Indonesia yang mencapai 94.067 unit pada tahun 2023 dapat menyebabkan berbagai permasalahan seperti kemacetan dan kecelakaan. Selain menimbulkan korban jiwa kecelakaan lalu lintas juga menyebabkan kerugian materi berupa kerusakan pada kendaraan seperti goresan atau penyok pada panel bodi mobil. Kerusakan tersebut dapat diperbaiki melalui proses pengecatan ulang untuk mengembalikan ke kondisi semula. Kualitas hasil pengecatan yang baik dapat dilihat dari nilai lekat dan nilai kilapnya. Nilai kilap menandakan kualitas hasil pengecatan yang dapat meningkatkan estetika dari sebuah kendaraan. Bengkel Yunex Paint yang beralamat di Desa Gesing Temanggung dipilih menjadi mitra pengabdian karena bergerak di perbaikan bodi dan pengecatan yang setiap minggunya mampu mengerjakan 2 unit mobil dengan total waktu pengerjaan 4-6 hari untuk pengecatan ulang panel bumper maupun kap mesin. Bengkel ini masih banyak menghadapi berbagai permasalahan pada  proses produksi seperti hasil pengecatan yang kurang mengkilap karena finishing masih dilakukan secara manual sehingga jumlah mobil yang dikerjakan tidak mengalami peningkatan menyebabkan perkembangan usahanya kurang signifikan. Mengatasi permasalahan tersebut maka diusulkan penerapan mesin rotary polisher yang diharapkan dapat meningkatkan efisiensi waktu dan kualitas hasil pengecatan, sehingga meningkatkan daya saing dan produktivitas Bengkel Yunex Paint. Pengabdian ini melibatkan 11 orang termasuk dengan pekerja bengkel. Metode pelaksanaan meliputi ceramah, demonstrasi, praktik langsung serta pendampingan, dan pengambilan data. Data hasil ukur daya kilap yang didapatkan yaitu 24,7 sebelum finishing, 85,3 sesudah finishing manual dan 94,1 sesudah finishing menggunakan mesin rotary polisher. Dari data yang didapatkan mesin rotary polisher dapat menambah nilai kilap hasil finishing pengecatan. Kata kunci: kualitas pengecatan; nilai kilap; mesin rotary polisher. Abstract The high number of motor vehicle sales in Indonesia, which reached 94,067 units in 2023, can cause various problems such as congestion and accidents. In addition to causing casualties, traffic accidents also cause material losses in the form of damage to vehicles such as scratches or dents on car body panels. The damage can be repaired through the repainting process to restore it to its original condition. The quality of good painting results can be seen from the adhesion value and gloss value. The gloss value indicates the quality of the painting results that can improve the aesthetics of a vehicle. The Yunex Paint workshop located in Gesing Village, Temanggung, was chosen as a service partner because it is engaged in body repair and painting which every week is able to work on 2 units of cars with a total processing time of 4-6 days for repainting bumper panels and hoods. This workshop still faces many problems in the production process such as painting results that are less shiny because finishing is still done manually so that the number of cars being worked on has not increased causing insignificant business development. Overcoming these problems, the application of a rotary polisher machine is proposed which is expected to increase the efficiency of time and quality of painting results, thereby increasing the competitiveness and productivity of the Yunex Paint Workshop. This service involved 11 people including workshop workers. The implementation method includes lectures, demonstrations, hands-on practice and mentoring, and data collection. The gloss measurement data obtained were 24.7 before finishing, 85.3 after manual finishing and 94.1 after finishing using a rotary polisher machine. From the data obtained, the rotary polisher machine can increase the gloss value of the painting finishing results. Keywords: painting quality; gloss value; rotary polisher machine

Thermal shock resistance investigation of evaporation boat waste-based crucibles

A crucible is a container shaped like a pot or a bowl used for smelting non-metallic materials, quality of the crucible can be influenced by several factors, including the selection of the constituent materials, the particle size used the amount of compaction pressure, and the length of firing time in the furnace. The selection of constituent materials is done by selecting the crucible-making mixture. The use of crucibles is for pyrometallurgical processes used for gold processing. Waste is closely related to pollution because this waste is the substance of environmental pollution therefore, waste treatment is needed so that it does not pollute the environment, the principles of solid waste management are prevention, recycling one example of solid waste is evaporation boats. Evaporation boats are included in one of the refractory materials because the waste from evaporation boats contains boron nitride (BN) and titanium diboride (TiB2) materials. So the purpose of this research was to determine thermal shock resistance of evaporation boat waste-based crucibles. The process of making specimens begins with crushing the evaporation boat waste with a crusher machine into powder, then sieved using a 120-mesh, then mixed with graphite, kaolin, and molasses using a mixer for 90 minutes until homogeneous mixture. The mixed material is then cast using molds according to ASTM D256 standards and pressed or compacted with a compacting tool worth 40 MPa. The specimens were then dried in an oven for four hours at 100°C, after that, the specimens were sintered at 1000 °C for 2 hours with a heating rate of 4 °C/min. The Compositions evaporation boat waste, graphite, kaolin, and molasses (75%, 15%, 10%, 30%; 75%, 20%, 5%, 30%; and 75%, 25%, 0%, 30%) are the materials used. Thermal shock treatment temperatures range from 100°C to 200°C, 300°C to 400°C, and up to 500°C. The results showed the highest average value of impact resistance was in composition 3 (75%, 25%, 0%, 30%) with a thermal shock temperature of 100°C worth 0.00501 J/mm2, and the lowest was in composition 2 (75%, 20%, 5%, 30%) at a thermal shock temperature of 500°C worth 0.00359 J/mm2. The average impact resistance value for each composition decreases, which is followed by an increase in the thermal shock temperature, This is because the higher the temperature of the thermal shock, the harder the specimen becomes and the specimen becomes brittle, variations in evaporation boat waste, graphite, kaolin, and molasses as crucible materials will be better if the use of kaolin in these compositions has a low presentation, even the highest average impact resistance value is in compositions that do not use kaolin on specimen composition 3