The article describes the application of computer simulation tools of the production system in the verification of planned deadlines for the production orders, realization in the company Regada, Ltd. Prešov. The requirement of our partner was the implementation of the computer model of the assembly hall with the subsequent simulation of the production flow of three orders of the linear direct servo drive. The material flow begins with the distribution of the material, whether produced in-house or purchased from suppliers, to the assembly hall. When solving the task, certain application limitations of the selected simulation environment were identified. Simulation experiments were realized on three computer models created in the Witness Horizon 21 environment. In two cases of monitored orders, experiments confirmed the unrealisticity of the proposed deadlines for their implementation. Computer simulation has the ability to evaluate the capacity of the production layout, the operation of the transport and storage system, information flow and management system.