MAINTENANCE MACHINE CNC MILLING LUNAN XHS7145 Mohd Fadhil NIM : 1604002010013 Jurusan Teknik Mesin, Program Diploma III Fakultas Teknik Universitas Syiah Kuala Email: mohdfadhilyz@gmail.com Abstract The production process can run effectively and efficiently when the machines used in the production process are in good condition and normal. Although the treatment system is done by the company during this time using the system preventive and corrective maintenance, but in the implementation there are still problems. The problem is due to unplanned and the absence of Standard Operation Procedure (SOP) in the Maintenance section to overcome the damage of CNC milling machine. Companies that do production activities without regard to maintenance activities, then the company is at risk of sacrificing the machine and the future of the company, because in the long term the company will have difficulties in the production process. The purpose of maintenance in Computer Numerical Control (CNC) Milling type machine, Brand: Lunan, type: XHS7145, is to perform maintenance steps on mechanic part XHS7145 system in accordance with standard Operation Procedure (In Operation Manual Book. Manage machine maintenance system maintenance. The stage that must be implemented so that the research can run smoothly and produce maximum data that is preparation of materials, preparation of equipment, implementation of observation, implementation of research, implementation of treatment, Data. The types of treatments planned according to the schedule of treatment period preventive are classified into inspections, small repairs, medium repairs, and total disassembly Password : Maintenance, Computer Numerical Control (CNC), Standart Operation Procedure (SOP)