In recent years, there has been a considerable increase in the demand of the plastics industry; therefore, many SMEs have not been able to cover their demands due to production problems, since there is a high number of unproductive hours in unnecessary movements, machine stoppage, and poor machinery maintenance planning, among others. The problem that could be identified and that occurs in most SMEs in the plastics sector is low availability due to unproductive times. The purpose of this article is to reduce downtime in production and consequently increase the OEE, since this represents a loss of money for the company, especially in the injection process.  Therefore, the idea is to implement the Lean Manufacturing model, which is validated with its TPM, 5s, ErgoSMED and Poka Yoke tools, in addition to the SLP implementation. To validate this improvement proposal, the Arena simulation software was used in a company in the plastics sector, since it will be possible to obtain a reduction of unproductive times by 20%, reduce travel times by 25%, reduce labor disorder in jobs by 15%, and in general increase availability by 12%, thus increasing the OEE indicator by 20%.