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All Journal Jurnal Rekayasa Mesin JTTM: Jurnal Terapan Teknik Mesin Cakrawala: Jurnal Pengabdian Masyarakat Global
Rahmat Doni Widodo
Unknown Affiliation
Aerospace Engineering Agriculture, Biological Sciences & Forestry Humanities Control & Systems Engineering Economics, Econometrics & Finance Education Engineering Languange, Linguistic, Communication & Media Mechanical Engineering Social Sciences

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Peningkatan Kompetensi Pengecoran Logam melalui Pemanfaatan Tungku Berbahan Bakar LPG dan Kowi Berbasis Limbah di SMK Negeri 2 Kudus Rusiyanto Rusiyanto; Rahmat Doni Widodo; Kaleb Priyanto; Ruben Bayu Kristiawan; Muhammad Zakky Mubarok; Muhammad Emir Al Hakim; Yudistira Rijal Andika; Hibban Pasya Hafid; Julivan Brian Womsiwor
Cakrawala: Jurnal Pengabdian Masyarakat Global Vol. 4 No. 3 (2025): Agustus: Cakrawala: Jurnal Pengabdian Masyarakat Global
Publisher : Universitas 45 Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30640/cakrawala.v4i3.4993

Abstract

This community service program aimed to improve vocational students’ competence in metal casting by introducing LPG-fueled furnaces and UNNES crucibles fabricated from evaporation boat waste. The partner, SMK Negeri 2 Kudus, faced two main challenges: limited utilization of aluminum scrap from automotive practice and the absence of affordable, durable crucibles for repeated casting activities. The program applied a structured approach consisting of socialization, training, mentoring, and evaluation. Activities included theoretical instruction, pretest–posttest assessment, and hands-on workshops involving furnace operation, crucible utilization, mold preparation, and aluminum casting. Results demonstrated significant improvements: the average pretest score of 4.85 increased to 9.0 in the posttest, reflecting an 85.57% gain in competence. Qualitative observations showed that students developed greater confidence, teamwork, and adherence to safety standards. Beyond competence improvement, the innovation provided a cost-effective and sustainable solution for recycling aluminum scrap and reducing dependence on expensive imported crucibles. The program effectively integrated research-based technology into vocational education and aligned with the Teaching Factory model. This collaboration between university and school can serve as a replicable model for other vocational institutions seeking to strengthen practical skills, sustainability, and industry relevance.
Investigasi Pengaruh Penuaan Termal terhadap Sifat Mekanik Karpet Felt Polyethylene Terephthalate Laminasi dengan Low-Density Polyethylene untuk Aplikasi Pengembangan Produk Quarter Trim Panel Nugroho, Rizky Fajar; Deni Fajar Fitriyana; Samsudin Anis; Rahmat Doni Widodo; Janviter Manalu; Januar Parlaungan Siregar; Tezara Cionita; Mochamad Marte Ardhianto
Jurnal Rekayasa Mesin Vol. 20 No. 1 (2025): Volume 20, Nomor 1, April 2025
Publisher : Mechanical Engineering Department - Semarang State Polytechnic

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jrm.v20i1.6208

Abstract

Penelitian ini bertujuan untuk mengevaluasi pengaruh penuaan termal pada sifat mekanik karpet felt polyethylene terephthalate (PET) yang dilaminasi dengan low density polyethylene (LDPE) untuk pengembangan quarter trim panel kendaraan. Latar belakang penelitian berfokus pada pentingnya material interior otomotif yang tahan lama. polyethylene terephthalate (PET) dikenal memiliki stabilitas termal dan kekuatan tarik tinggi, sementara low density polyethylene (LDPE) menawarkan fleksibilitas. Namun, penelitian terkait kombinasi laminasi polyethylene terephthalate (PET) dan low density polyethylene (LDPE) dan dampak penuaan termal terhadap sifat mekaniknya masih terbatas. Metode penelitian mencakup persiapan spesimen, pengujian tarik sebelum dan setelah penuaan termal pada suhu 70 °C selama 72 jam dalam kondisi panas kering, serta analisis struktur molekuler. Hasil penelitian menunjukkan penurunan signifikan pada kekuatan tarik, di mana spesimen cross direction (CD) menurun dari 58,5 MPa menjadi 40 MPa, dan terjadi peningkatan modulus elastisitas sebesar 20%. Penurunan ini disebabkan oleh degradasi molekuler dan reorganisasi struktur amorf polyethylene terephthalate (PET) yang mengurangi kohesi antar molekul. Kesimpulannya, penuaan termal berdampak negatif pada sifat mekanik karpet felt polyethylene terephthalate (PET) yang dilaminasi low density polyethylene (LDPE). Penelitian ini memberikan wawasan penting untuk pengembangan material interior kendaraan yang lebih tahan lama dan menekankan perlunya peningkatan stabilitas termal pada laminasi (PET) dan low density polyethylene   (LDPE).
Penerapan Siklus Plan-Do-Check-Action untuk Mengurangi Cacat Permukaan pada Produk Outer Tube Model 2DP di PT. XYZ Putra, Naufal Bahy; Deni Fajar Fitriyana; Samsudin Anis; Rahmat Doni Widodo; Janviter Manalu; Januar Parlaungan Siregar; Tezara Cionita; Mochammad Marte Ardianto
Jurnal Rekayasa Mesin Vol. 20 No. 1 (2025): Volume 20, Nomor 1, April 2025
Publisher : Mechanical Engineering Department - Semarang State Polytechnic

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jrm.v20i1.6211

Abstract

Tingkat cacat permukaan pada outer tube model 2DP di area pemesinan PT.XYZ masih mencapai 3,91%, melebihi Key Performance Indicator (KPI) perusahaan sebesar 1,36%. Kajian terdahulu membuktikan efektivitas siklus Plan-Do-Check-Action (PDCA) di berbagai sektor, namun belum ada penelitian empiris yang memfokuskan penurunan cacat permukaan komponen otomotif pada proses pemesinan di Indonesia dan mengukur dampak langsung integrasi PDCA terhadap pencapaian KPI serta penghematan biaya perbaikan. Oleh karena itu, penelitian ini bertujuan untuk menurunkan cacat permukaan outer tube model 2DP mencapai KPI sebesar 1,36% dan menghemat biaya pengerjaan ulang. Metode yang digunakan dengan mengkombinasikan 8 Langkah Toyota Production System (TPS), diagram Pareto, dan diagram ishikawa untuk mengidentifikasi akar penyebab dan menetapkan prioritas perbaikan. Dengan melakukan perbaikan meliputi, pemotongan dua-tahap (roughing-finishing), modifikasi program turning, penggantian diameter tool rib, dan penggunaan jig semi-cavity, hasil penelitian menunjukkan penurunan tingkat cacat permukaan pada produk outer tube model 2DP dari 3,91% menjadi 1,32% serta memberikan penghematan biaya tahunan perusahaan hingga Rp. 600.780.000. Kesimpulannya, integritas siklus PDCA menggunakan 8 langkah TPS dan alat bantu kualitas efektif dalam meningkatkan kualitas produk dan efisiensi biaya di industri Otomotif. Penelitian ini memperluas bukti empiris lean manufacturing di industri otomotif di Indonesia, menyediakan kerangka praktis perbaikan berbiaya rendah namun berdampak tinggi serta integrasi dengan teknologi industri 4.0.
Analysis of impact strength and hardness of waste HDPE composites reinforced with ijuk fiber Nurfahmi, Ilyas; Rahmat Doni Widodo; Muhammad Irfan Nuryanta
JTTM : Jurnal Terapan Teknik Mesin Vol 7 No 2 (2026): JTTM: Jurnal Terapan Teknik Mesin
Publisher : Teknik Mesin - Universitas Muhammadiyah Cileungsi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37373/jttm.v7i2.2274

Abstract

The utilization of HDPE waste as a composite material is increasingly developing due to the industry's demand for materials that are lightweight, economical, and environmentally friendly. The properties of ijuk fiber, which has high strength and good elasticity modulus, make HDPE polymers stronger when used to be transformed into composite materials. The aim of this study is to analyze the effect of variations in the mass fraction of ijuk fiber on the mechanical properties of HDPE-based composites through impact and hardness tests. The composite material was made using HDPE plastic bottle caps as the matrix and alkalized ijuk fiber as reinforcement, with fiber mass fraction variations of 0%, 10%, 15%, and 20%. Specimens were made using an oven at 150°C, followed by hydraulic hot pressing at a pressure of 90 tons. Mechanical characterization was conducted using Charpy impact testing (ASTM D6110) and Shore D hardness testing. The research results show a consistent increase in mechanical properties with the increasing fraction of fibers used. The highest impact test result of 0.285 kJ/m² was obtained at a 20% fiber content, and the highest hardness test result of 60.89 Shore D was obtained at a 20% fiber content. These results indicate that the addition of ijuk fibers improves the energy absorption value and surface resistance of HDPE composite materials. Therefore, adding fibers up to 20% effectively enhances the mechanical performance of HDPE composites reinforced with ijuk fibers
Co-Authors Fitriyana, Deni Fajar Hibban Pasya Hafid Januar Parlaungan Siregar Julivan Brian Womsiwor Manalu, Janviter Mochamad Marte Ardhianto Mochammad Marte Ardianto Muhammad Emir Al Hakim Muhammad Irfan Nuryanta Muhammad Zakky Mubarok Nugroho, Rizky Fajar Nurfahmi, Ilyas Priyanto, Kaleb Putra, Naufal Bahy Ruben Bayu Kristiawan Rusiyanto Rusiyanto Samsudin Anis Tezara Cionita Yudistira Rijal Andika