A Novel MILP Model for the Production, Lot Sizing, and Scheduling of Automotive Plastic Components on Parallel Flexible Injection Machines with Setup Common Operators

Abstract

In this article, a mixed integer linear program (MILP) model is proposed for the production, lot sizing, and scheduling of automotive plastic components to minimize the setup, inventory, stockout, and backorder costs, by taking into account injection molds as the main index to schedule on parallel flexible injection machines. The proposed MILP considers the minimum and maximum inventory capacities and penalizes stockout. A relevant characteristic of the modeled problem is the dependence between mold setups to produce plastic components. The lot sizing and scheduling problem solution results in the assignment of molds to machines during a specific time period and in the calculation of the number of components to be produced, which is often called lot size, following a sequence-dependent setup time. Depending on the machine on which the mold is setup, the number of units to be produced will be distinct because machines differ from one another. The stock coverage, defined in demand days, is also included in the MILP to avoid backorders, which is highly penalized in the automotive supply chain. Added to this, the proposed model is extended by considering setup common operators to respond to and fulfill the constraints that appear in automotive plastic enterprises. In this regard, the MILP presented solves a lot-sizing and scheduling problem, emerged in a second-tier supplier of a real automotive supply chain. Finally, this article validates the MILP by performing experiments with different sized instances, including small, medium, and large. The large-sized dataset is characterized by replicating the amount of data used in the real enterprise, which is the object of this study. The goodness of the model is evaluated with the computational time and the deviation of the obtained results as regards to the optimal solution.

Linear Programming Model for Production Cost Minimization at a Rice Crop Products Manufacturer

“…Other approaches aligned with this study are related to the distribution of production activities or results, seeking the minimization of costs or waste, or the maximization of benefits or profits, through the optimization of resources. [18] proposes a mixed-integer linear programming (MILP) model to minimize costs of installation, stock outages and pending orders, in which the model aims to program production, batch size and plastic automotive components, to which end he takes into consideration the capacity of minimum and maximum stock levels and penalizes stock outages. In this study, the problem to be addressed is programming and sizing of optimal batches in flexible injection machines in parallel, applied to an automotive plastic components manufacturer.…”