The aim of any maintenance plan is to improve machine availability. Modern manufacturing involves complicated machines and high levels of automation. The goal of automated equipment is to increase production rates while improving quality. As a result, machines must be kept in working order to deliver the desired outcome or goal. Machine failures or breakdowns cause production to be disrupted, resulting in the present system's availability being lost. This influences the production, expense of maintenance and commitment to customer. The present work aims at increasing operational availability of the Machines. One engine block manufacturing system consisting of three lines, each line having no of machines, a few critical machines were identified on the criteria of capacity and breakdowns and these breakdowns were analysed with FMEA, RCA, Why-Why analysis, etc. Implementation is in the form of a customised maintenance plan that reduces the breakdown and shifts the maintenance from reactive to proactive. The following parameters like MTTR, MTBF and Machine Uptime % and the production quantity were compared with previous year data in CMMS. The implemented maintenance plan helps to improve production rate and the machine operational availability.