The increase in automation due to the changing market and the expansion of product diversity has led to an increase in the demand for more sophisticated equipment. As a result, the dependability and maintainability of equipment have become critical in managing the quantity and quality of the products produced. Therefore, preventive maintenance (PM) should be performed during the manufacturing process in order to ensure the stipulated reliability and dependability of the production process specifications. Unscheduled PM, on the other hand, can have detrimental financial implications for the company, as well as a reduction in the overall production line reliability. This work considers a realistic multi-objective PM scheduling problem in a production line at a local Saudi glass plant. The reliability of the production line, maintenance costs, and system downtime are measured as multiple objectives, and different thresholds are applied for the available budget and maintenance periods. The aim is to apply a mathematical model to maximize the system’s reliability and minimize overall costs. The results of the multi-objective model have shown a significant decrease in cost of about 12%.