In the plastics sector, companies face a significant challenge: a high rate of defective products, primarily due to machinery failures, operational errors, inadequate procedures, and variability in raw materials. This problem affects not only operational efficiency but also economic costs by increasing reprocessing and generating losses from the disposal of non-conforming products. To address this situation, an improvement is proposed based on process standardization, the 5S methodology, the implementation of preventive maintenance through a CMMS (Computerized Maintenance Management System) system, and IoT (Internet of Things) technology for real-time monitoring of critical machinery. Unlike research that promotes the immediate use of Predictive Maintenance, this proposal recognizes that its application is not currently viable in many Peruvian SMEs due to the lack of digital infrastructure. In this sense, the implementation of CMMS drives the digital transformation of maintenance by enabling the systematic planning, monitoring, and documentation of activities, while IoT—central to Industry 4.0—enhances real-time data collection from critical equipment, enhancing operational visibility. Together, they establish the foundation for future integration of AI-driven systems aligned with Industry 5.0. The proposal addresses the urgent need to reduce assembly errors and recurrent failures in machines such as extruders and sealers. The improvement model was validated through simulations in Arena software, and its implementation was carried out in a Peruvian company in the plastic packaging sector. The results show a reduction in the defective products rate from 10.42% to 5.24%, and a 69.81% decrease in machine incidents. In conclusion, this research demonstrates that a progressive digital transformation, initiated with Industry 4.0 tools, is viable and effective in the context of manufacturing companies with limited resources.