Analysis of Reactive Injection Compression Molding by Numerical Simulations and Experiments

Abstract

Injection compression molding is an injection molding process with the addition of a compression stage after the injection. This process is useful for the injection molding of precision parts. A stable and controlled manufacturing process is needed to guarantee reliability of complex products, and usually process optimization is achieved by experimental and time consuming approaches. However, for being competitive a minimal market time is a very important requirement and computer simulations can help to optimize the process at the only expense of computational time. This paper reports and discusses for the first time the results of a 3D finite element simulation of reactive injection compression molding (RICM) by commercial software for the production of rubber diaphragms. In particular, the stages of mold filling dynamics and material curing are analyzed and the results verified with experimental tests. To get an accurate representation of the process, the rheological behavior, thermal properties, and kinetic behavior during curing of the real rubber compound were described by mathematical models. A differential scanning calorimeter (DSC) and a capillary rheometer are employed to characterize the rubber material in order to achieve an appropriate curing reaction and viscosity models, respectively. The computations are found to be in good agreement with the experimental results, indicating that reliable information on material viscosity and curing kinetics can play a key role in making well-founded predictions and avoiding trial and error methods.

Temperature Profile in Rubber Injection Molding: Application of a Recently Developed Testing Method to Improve the Process Simulation and Calculation of Curing Kinetics

“…The common practice of setting up an injection molding simulation revealed that the initial mass temperature is often assumed to equal the set temperature of the plasticizing cylinder of an injection molding machine. Ramorino et al [ 16 ] recently compared results from a real manufacturing process and simulation using an acrylonitrile butadiene rubber (NBR) and they hypothesized that the initial mass temperature had negligible effects on the results of the numerical calculations. Contrary findings were obtained in this work by measuring the actual state of the mass temperature profile with the previously described test stand.…”

“…Fasching et al [ 14 , 15 ] showed in subsequent research the importance of correct determination of the mass temperature profile after dosing. Direct measurement of this temperature in the plasticizing cylinder is technically not possible, which is why the initial mass temperature in simulations often equals the set (constant) temperature of the plasticizing cylinder defined at the injection molding machine [ 16 ]. Therefore, Fasching proposed a higher initial set temperature for the rubber compound applied in simulation.…”

Injection‐compression molding process on optical quality optimization of plastic lens array

“…Finally, the mold is opened and the finished part is ejected and allowed to cool naturally to room temperature (Figure 1D). [1][2][3][4] The ICM process provides a quick and convenient approach for the mass production of plastic components with both simple and complex geometries. However, residual stress is easily accumulated within the molded component during the compression and packing stages, and this often leads to the warpage of the component as it undergoes cooling following ejection from the mold.…”

“…Finally, the mold is opened and the finished part is ejected and allowed to cool naturally to room temperature (Figure 1D). 1–4 …”

Optimization of Injection-Compression Molding Processing Conditions for Fresnel Lens Based on Optical Performance and Geometry Deformation Considerations

“…Finally, the mold is opened, and the finished component (e.g., a Fresnel lens) is ejected (Fig. 1d) [1][2][3][4]. Compared to the traditional injection molding process, ICM reduces the injection pressure required to fill the cavity and improves the uniformity of the compression force within the mold.…”