This research article focuses on the ergonomic design of the workstations for the plastics industry plant to reduce the postural load that improves the workers’ productivity and the operators’ absenteeism due to musculoskeletal disorders. This article develops an innovative solution to deal with one of the main problems of the plastic industry, namely, the high rate of worker absenteeism generated by musculoskeletal disorders due to the high postural load at the stations of work in this industry. The research is divided into four stages, namely the Determination of the objectives through the analysis of the problem and its root causes, the Redesign of the work methodologies in the productive area, the Improvement in the activities and tools used in the production chain, and Evaluations of the different impacts that the proposal entails. A proposed model validated with the Delmia V5 software and evaluation methods such as RULA, REBA, and OCRA, made possible a reduction in the level of risk of 50% and 66.7% in the different jobs analyzed and obtained 42,929 PEN in savings per year in respect to the total costs generated by the absenteeism presented. The result of the new workstations satisfies the ergonomic aspects and the needs of the workers. The study focuses on an analysis of risk levels that occurred in each of the high-density bag production activities, where non-conformity was found regarding the high risks presented, those leading causes with inappropriate postures by the staff, non-optimal working conditions, and absence of ergonomic furniture. This research serves as the basis for future lines of research and other companies with similar characteristics to implement the model.