The present research proposes a implementation model of Lean Manufacturing starting from a production system defined with Theory of Constraints (TOC). The paper describes a case study at a major Ecuadorian footwear company with the aim of reducing delivery times and inventories generated by work in process. Value stream mapping is used to identify wasteful action as opportunities for improvement and with the implementation model both Lean and Theory of Constraints tools are applied. The analysis of activities that add and do not add value in the value stream of the current state and then allows to develop the map of the future state from the relationship between the analysis of constraints and the inventory of the TOC and Pull production and takt time of Lean. The results allow to demonstrate the successful application of the model in the footwear industry with a reduction in nonvalue-added time and inventory of 40% and 78% respectively.

An important aspect in the operation of production systems is to reach the desired amount in the established times and with the minimum volume of inventory in process. To achieve this goal, production control systems are used which are characterized by the effect exerted on the materials flow, whether they are push or pull. In this research a comparative study is made between the production control methodologies of the Pull type system: Kanban, Conwip and DBR, in order to clarify the differences between the different operating mechanisms used by each of them, making use of production parameters such as work in process WIP, cycle time CT and production rate TH to determine the model that presents a better performance. In order to comply with the objective proposed in this project, simulation models were programmed using the Promodel software with the processes of a textile manufacturing industry obtaining as a result that the strategy that presents a better result with respect to the established production parameters is Kanban since an average inventory of 4 lots was obtained, i.e., it presents a reduction of 79.8% compared to the current system. In addition, an average cycle time less than 6.11 hours that represents a 61.1% decrease and a production rate of 0.65 batches/hour.

El sobreesfuerzo por actividades en las que existe manipulación manual de cargas es una de las principales causas para la aparición de afectaciones músculo–esqueléticas. La presente investigación tiene por objetivo la evaluación ergonómica de actividades de manejo y transporte de cargas en trabajadores de mantenimiento vehicular pesado. La valoración del riesgo se la realiza con los métodos UNE-EN-1005-2 y Manual Handling Assessment Charts (MAC), la capacidad física de trabajo se estable a través de la prueba escalonada de Manero, mientras que la sintomatología músculo-esquelética se analiza mediante una versión adaptada del cuestionario Nórdico de Kuorinka. Los resultados de la valoración indican que el 30,4% de las actividades tienen un riesgo inaceptable de nivel alto que puede afectar negativamente la zona lumbar, el método MAC establece que el 18,75% de las actividades presentan un riesgo alto de daño a la integridad física de los trabajadores, en cuanto a la prueba escalonada, el 100% del personal estudiado posee una capacidad física de trabajo (CFT) alta para su edad (>45 ml/Kg*min). Las regiones corporales de los trabajadores que más impactos negativos presentan son en la zona lumbar, rodillas y en menor medida en las extremidades superiores.

This research proposes to use Lean Manufacturing techniques to get Distribution Requirements Planning (DRP). The paper describes a case study at a major Ecuadorian flour industry, with lean manufacturing techniques the aim is improve and optimize the production system, reducing delivery times, wasteful action and inventories generated by work in process. Value stream mapping is used to identify wasteful action as opportunities for improvement and through the DRP matrix the inventory rotation and the distribution operation were improvement allowing a greater flow of money for the company. The results allow to demonstrate the successful application of the model in the flour industry with a reduction in nonvalue-added time and an improvement of 13.8% in the production process time, based on this, a improved production plan based on the distribution requirements can be elaborated.