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All Journal Jurnal Rekayasa Mesin Jurnal Bahan Alam Terbarukan
Januar Parlaungan Siregar
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Chemical Engineering, Chemistry & Bioengineering Mechanical Engineering

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Synthesis of Hydroxyapatite from Green Mussel Shells Using Micro-wave Method Through Ultrasonic Mixing Process and Magnetic Stirrer Stirring Agus Prasetyo; Risky Ismail; A. P. Bayuseno; Samsudin Anis; Deni Fajar Fitriyana; Muhammad Afrizal; Januar Parlaungan Siregar
Jurnal Bahan Alam Terbarukan Vol. 14 No. 1 (2025): June 2025 [Nationally Accredited Sinta 3]
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jbat.v14i1.25497

Abstract

Hydroxyapatite (HAp) is a biomaterial containing calcium phosphate with the chemical formula which is similar to the structure of human bone, so it is good for the purpose of healing human bones and teeth. HAp synthesis has several methods that can affect the results of HAp synthesis, such as the method of mixing CaO with phosphate, namely mixing with ultrasonic machines and magnetic stirrers. However, the discussion about the difference of HAp results with the mixing method of ultrasonic machine and magnetic stirrer is still rarely done. Therefore, it is important to examine and compare the characteristics of HAp synthesized by ultrasonic and magnetic stirrer mixing. The result of XRD test shows that HA1 has a purity of weight percentage (wt.%) of HAp crystal of 99.8%, while HA2 has a weight percentage (wt.%) of HAp crystal of 97.7%. For the FTIR test results of both specimens detected the presence of phosphate groups, and hydoxide, where both are the basic form of hydroxyapatite. Carbonate groups were also detected in the test, but it cannot be said to be bad because carbonate is a natural substitute for phosphate. 
The Effect of KNO3 Addition on the Properties of Coconut Shell Charcoal Briquettes Achmad Erlangga Bintang Samodra; Fitriyana, Deni Fajar; samsudin anis; janviter manalu; Al Ichlas Imran; Januar Parlaungan Siregar; Tezara Cionita
Jurnal Bahan Alam Terbarukan Vol. 14 No. 1 (2025): June 2025 [Nationally Accredited Sinta 3]
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jbat.v14i1.26289

Abstract

This research investigates the effects of incorporating potassium nitrate (KNO₃) into coconut shell charcoal briquettes, emphasizing their physical and chemical characteristics. Briquettes were manufactured utilizing coconut shell charcoal powder, tapioca flour as a binder, and different concentrations of KNO₃ (0% and 10%) as an additive. The aim was to assess the impact of KNO₃ incorporation on the water content, ash content, volatile matter, fixed carbon, calorific value, and density of the briquettes. The findings indicated that incorporating KNO₃ resulted in elevated water and ash content, adversely affecting combustion efficiency. Briquettes with increased water content demonstrated reduced mechanical strength and inferior combustion performance. The addition of KNO₃ led to an increased volatile matter content, facilitating ignition of the briquettes while simultaneously resulting in higher smoke emissions. The addition of KNO₃ resulted in a decrease in fixed carbon content, which subsequently lowered the calorific value of the briquettes. The formulation without KNO₃ produced the densest briquette, suggesting that including KNO₃ reduced the briquette density. The inclusion of KNO₃ enhances ignition characteristics; however, it concurrently diminishes the briquettes' overall quality regarding combustion efficiency and calorific value. The Briquette B_1 exhibited the highest results in this investigation, with water content, ash content, volatile matter, fixed carbon content, calorific value, and density values of 4.97%, 1.87%, 17.25%, 80.88%, 7014 Cal/g, and 0.90 g/cm³, respectively.
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.
Co-Authors A. P. Bayuseno Achmad Erlangga Bintang Samodra Agus Prasetyo Al Ichlas Imran Fitriyana, Deni Fajar Manalu, Janviter Mochamad Marte Ardhianto Mochammad Marte Ardianto Muhammad Afrizal Nugroho, Rizky Fajar Putra, Naufal Bahy Rahmat Doni Widodo Risky Ismail Samsudin Anis Tezara Cionita