Electronic Theses and Dissertation

Penggunaan cairan pemotong konvensional berbasis minyak mineral pada proses pemesinan menimbulkan permasalahan lingkungan dan kesehatan. Oleh karena itu, penelitian ini bertujuan untuk mengkaji kelayakan minyak nanofluid CuO berbasis campuran minyak goreng bekas (waste cooking oil/WCO) dan minyak kastor (Castor Oil/CO) sebagai cairan pemotong alternatif ramah lingkungan pada proses frais material SKD-11 dengan metode Minimum Quantity Lubrication (MQL). Nanofluid dibuat dengan menambahkan nanopartikel CuO sebesar 0,5% berat ke dalam beberapa variasi komposisi campuran WCO–CO, kemudian didispersikan menggunakan mechanical stirring dan ultrasonic homogenizer. Proses pemesinan dilakukan pada mesin CNC milling dengan pahat karbida insert single flute. Kinerja pemesinan dievaluasi berdasarkan parameter gaya potong, kekasaran permukaan, topografi permukaan, serta dibandingkan dengan kondisi Dry machining dan minyak tanpa penambahan nanopartikel. Hasil penelitian menunjukkan bahwa penggunaan nanofluid CuO pada campuran WCO–CO mampu menurunkan gaya potong dan temperatur pemotongan secara signifikan, serta menghasilkan kualitas permukaan yang lebih baik dibandingkan kondisi Dry dan minyak murni. Campuran WCO–CO dengan penambahan CuO menunjukkan kinerja pemesinan yang stabil dan efektif, sehingga berpotensi menjadi alternatif cairan pemotong yang ramah lingkungan dan ekonomis untuk pemesinan material keras seperti SKD-11.

Kata Kunci: Minimum quantity lubrication (MQL), Nanopartikel CuO, WCO, CO, Gaya potong, Kekasaran permukaan, Topografi Permukaan.

The use of conventional mineral oil–based cutting fluids in machining processes raises environmental and health concerns. Therefore, this study aims to investigate the feasibility of CuO nanofluid–based cutting fluids formulated from a mixture of waste cooking oil (WCO) and castor oil (CO) as an environmentally friendly alternative for the milling process of SKD-11 material using the Minimum Quantity Lubrication (MQL) method. The nanofluids were prepared by adding 0.5 wt.% CuO nanoparticles to various compositions of WCO–CO mixtures, followed by dispersion using mechanical stirring and an ultrasonic homogenizer. Machining experiments were conducted on a CNC milling machine using a single-flute carbide insert tool. Machining performance was evaluated based on cutting force, surface roughness, surface topography, and cutting temperature, and the results were compared with dry machining conditions and base oils without nanoparticle addition. The results show that the application of CuO nanofluids in WCO–CO mixtures significantly reduces cutting force, while producing improved surface quality compared to dry machining and pure oil conditions. The WCO–CO mixtures with CuO nanoparticles exhibit stable and effective machining performance, indicating their strong potential as an environmentally friendly and cost-effective alternative cutting fluid for machining hard materials such as SKD-11. Keywords: Minimum quantity lubrication (MQL), CuO nanoparticles, WCO, CO, Cutting force, Surface roughness, Topography.