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Browsing by Author "Orejuela Cabrera, Juan Pablo"

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    Reducción de desperdicios de materia prima en una empresa del sector metalmecánico mediante la implementacion y modelación del cutting stock problem
    (Corporación Universitaria Lasallista, 2014) Orejuela Cabrera, Juan Pablo; Peña Calderón, Diana Andrea; Gil González, Cristiam Andrés
    Introduction . Cutting stock problem covers the issue of cutting big rolls of any material (paper, fabrics, steel, wood, etc) in small shreds with different widths that, can, then, be used as the raw materials to elaborate a final product. The lengths of these shreds are defined by the clients or according to the specific conditions required by the production process. Objective. Developing a mathematical model that allows the planning and the programming of a cutting process for steel rolls in order to solve the question “how to configure the cutting of rolls satisfying the requirements of the demand and simultaneously minimize the remains and the inventory levels in a metallurgic company? materials and methods. A methodological model was made and applied in a production plant in which Steel pipes are made. Waste levels of about 15 % per cut roll were found in the place. Results. This, under lost weight terms, reached up to 25 tons per 1700 tons produced in a month, thus making the inventory levels of in process products to be exceeded by up to 24 % of the storage capacity. Conclusions. The main result of the methodology is a 4 % reduction of the weekly cost of waste, compared to the real process of the company.
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    Scheduling of internal materials supply operations in a pre-milling type concentrate food plant
    (Corporación Universitaria Lasallista, 2017) Rojas Trejos, Carlos Alberto; Saavedra Arango, Luis Felipe; Orejuela Cabrera, Juan Pablo
    Introduction. This research addresses the problem of internal materials supply operations in a pre-milling type concentrate food plant. The required amount of raw materials for production in the internal supply chain is determined by minimizing the total relevant operational cost, made up by the setup cost and the stock maintenance cost, which maximizes efficiency of the resources used in the process. This study takes into account such factors as capacity of the hoppers, the time-dependent setup sequence, routes of supply hoppers, filling rates and supply times, based on a model of mixed-integer linear programming. Objective: Provide a strategy that allows efficient use of resources in the production process, subjected to the demand of materials from the material requirements planning (MRP) of the company under study. Materials and methods. The short-term multi-period model defines the scheduling of elevators and conveyors for each time period, and the amount of raw materials that is sent to each hopper and bins. Results. This research determines the amount of initial stock required to operate, as well as the operations strategy that the company under study must follow, so that it meets the demand for raw materials, making efficient use of the resources used in the production process. Conclusion. In the analysis of results and presentation of scenarios, the most representative cost, the one related to stock maintenance, could be observed. Since this is a critical factor for companies belonging to this sector, we present an innovative proposal, both in practice and in the literature, to contribute to minimizing the total setup cost and the cost of maintenance of raw material stock in hoppers through a rational use of resources.
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    Simulation-optimization model to determine the installed capacity of an educational services system
    (Corporación Universitaria Lasallista, Editorial Lasallista, 2016) Gil González, Cristiam Andrés; Manyoma Velásquez, Pablo César; Orejuela Cabrera, Juan Pablo
    The problem of determining the capacity in service companies is the lack of clear methodologies. As for academic institutions, the research advances on the subject are even more reduced. The literature available has widely covered other problems affecting capacity, and also the programming and the planning of staff, facilities and schedules without directly measuring capacity. Objective. To create a generic methodology to determine the capacity of an educative services system (schools, universities, etc) in terms of the quantity of students to serve with the institution ́s infrastructure. Materials and methods. Firstly, a methodology to simulate the capacity used by the students throughout time is created. Then, with this information, an optimization model to calculate the maximum number of students that can be admitted is executed. Results. The model developed is applied in the Engineering School of Universidad del Valle, Colombia, where it was found that 25% more of students could have been admitted, using about 20 % of the capacity that can be potentially used. Conclusion. This methodological model is useful to know the capacity in terms of the number of students an institution can receive. It also facilitates midterm decisions, especially the measurement of the impact of the policies that can be formulated to favor the maximization of the service standards of the institution, and also, for instance, the impact of building new infrastructures.