This research sought to improve the assembly process, specifically of the desktop computers of the Infotec company, from the implementation of lean tools that allow diagnosing, measuring, and implementing new improvements or modifications in certain stages in order to improve both the level of service as the lead time of the total process. Each stage of the process had to be analyzed together with the company's technicians in order to obtain information on the current situation. Among the main findings, the lack of updating of the work tools, poor organization of the workshop, and a moderate amount of lead time were identified, this through the use of the Pareto Diagram, DOP, VSM, DAP, and photographic evidence. In addition, a high expense was found in complaints that represent 30% of the fixed costs, which corresponds to the internal failures of the computer, due to the poor assembly of the components, the overtime that the workers comply with, and the poor organization of the workshop. Therefore, the lean tools used were Six Sigma, SMED, and Poka Yoke. These allowed to propose new improvements and modifications both in the assembly process and in the work area. The Arena software was used to capture the current situation and later a new one, with the improvements implemented, evidencing an improvement of approximately 20 minutes. This investigation had certain drawbacks at first, as the company made it difficult to collect data to obtain the current situation. However, it was managed to settle it through negotiation.