Siregar, JamesFadilah, NurulROZAQ, ARIEFIN ABDUL2025-04-162025-01-13Surface roughness-https://repository.polibatam.ac.id/handle/PL029/3981-Grinding process is a process of reducing material to be a product. Feeding is carried out by a grinding disc which rotates against the workpiece on the table which moves left or right (in the x-axix direction). This feeding process will result in differences in the surface roughness of the workpiece. Surface Roughness is the arithmetic mean deviation from the profile mean line. Therefore, to obtain a quality product in the form of a high level of precision and good surface roughness, it needs to be supported by an appropriated machining process. Evaluation of surface roughness is very important for many basic problems, for example friction in materials. This study aims to compare the surface roughness of AISI 4140 and Mild Steel SS400 after going through the same grinding process. Data is obtained by measuring the level of workpiece roughness using the Surface Roughness Tester. This comparison aims to find out which material is better for making pivot flange. The pivot flange is the link between the shaft and the flange which is use as a fulcrum. The Surface Roughness tester machine shows 3 parameters of roughness, namely the arithmetic average roughness (Ra), the quadratic average roughness (Rq), and the total average roughness (Rz). The result show that the Mild Steel SS400 material has a lower average roughness, where the Ra is 30.4 μm. A finer material is needed to make a pivot flange because it can be reduce the friction and wear of the material. Keywords: Surface roughness, grinding process, AISI 4140 and Mild Steel SS400.otherTECHNOLOGY::Materials science::Functional materialsDatasetNIM3412011036NIDN0020118803NIDN0009089003KODEPRODI21401#Teknik Mesin