**1. Introduction**

Extrusion molding simulation allows you to avoid or reduce the high costs of the manufacture of the die or head and the probability of avoiding problems during production. On the other hand, costly modifications are saved, eliminating the current trial-and-error process, which added to the loss of time and lost profits, making simulation a tool of great importance for the national industry, especially for small- and medium-sized companies, since computer tools are not used in the

design of heads and in the extrusion process of thermoplastic profiles in our country. Computer simulation, using specific software, allows to accelerate these processes, making possible all the necessary considerations in the design before building the head, especially for processes and design of profiles with complicated geometries and even with the use of different types of materials to manufacture the same. In addition, it is also important to know how to design a caliper in order to obtain an extruded profile with the desired final geometry and dimensions [1].

As antecedents of the international research works that were carried out on the subject, some of them can be cited, although there are differences with respect to the present work, and in the materials, simulation software and extruder equipment, including the ones used in the final process of calibration and cooling of the profile, are the ones that most resemble it.

Therefore, we can cite the one carried out by Srinivasa et al. [2], in which the simulation is performed on an existing head with Polyflow software that uses computational fluid dynamics, with a double screw extruder and using polystyrene as a material, which is simpler to process than the composite of rigid PVC that uses the reverse extrusion simulation process with the objective that the results of the same are used to improve the design of a new head. In the conclusion, it is commented that discrepancies were found between the results of the computational simulation and the extrusion in the dimensions of the profile between 5 and 10%.

On the other hand, the work of Gupta [2] can be cited, who uses the finite element method for a three-dimensional simulation applied to the flow of the molten polymer and analyzes the shear and elongation viscosity in the head in a final rectangular way, which is represented by the truncated power law model. In this work, he obtains a recirculation of the molten material at the vertices and a loss of pressure, which causes an abrupt contraction that increases rapidly with the exponent *n* of the power law. Therefore, it manages to avoid the said recirculation and pressure loss, so that the contraction in the final profile is less pronounced.

Finally, Bogale [3] in his thesis work on design and simulation of a head for a rectangular profile, through modeling and simulation using the COMSOL Multiphysic software and the CA-RREAU model [4], also uses the low-density polyethylene as a study material and with a temperature of 220°C in the head. With the characteristics of the extruder screw, the flow rate is calculated, with which the pressure in the extruder could be obtained, since when it is minimum the output flow is maximum and vice versa. Although the design of the head was optimized in order to obtain a homogeneous distribution of the shear stress in the cross section of the same, it was not possible to simulate the exact dimensions of the head for a rectangular profile with the Comsol software.

In addition, this research aims to evaluate the predictive capacity of the Polyflow simulation software that uses computational fluid dynamics. Zhao [5] applied to the case of a rigid PVC profile, which has certain particular characteristics such as the aforementioned thermal sensitivity.

Thus, from the simulation, the contour values of the profile at the head outlet, the distribution of speeds that influence the contractions and stresses in the final profile and also the deformations and shear stresses that determine the physical and mechanical properties of the final profile, are obtained. In addition, the extrusion of the profile is carried out, at a certain RPM of the screw, obtaining the values of the same from the pressure and temperature sensors in the head, and on the other hand, the mass flow at the outlet of the head is measured. Subsequently, the results of both processes are compared and the results that are described in detail below in the corresponding item are obtained.

*Design, Simulation, and Analysis of the Extrusion Process of a PVC Thermoplastic Profile… DOI: http://dx.doi.org/10.5772/intechopen.100909*
