Simulation of the Melting Behavior in an Injection Molding Plasticizing Unit as Measured by Pressure and Ultrasound Measurement Technology

The melting behavior of a Polyamid material in an injection molding plasticizing unit (40/20D) was simulated and experimentally verified. Hence, a simulation program with a focus on standard three-section screws was developed. A clear separation of the melt and solid fraction in the screw channel is a precondition, referring to physical models, which are included. For this reason, the main constituent of the simulation program is the calculation of the melting process in an injection molding plasticizing unit. First of all, a 2D grid generator is used to represent an unwrapped screw channel of a standard three-section screw. Under consideration of the axial screw movement, mechanical, mathematical and physical models based on Tadmor, Gogos, White and Potente, it is possible to determine the melting process of the individual functional areas. Validation of simulation and experiment data is indispensable to get significant results. In order to verify the measurement relating to the melting profile, so called pull-out tests are normally executed. This method is very time-consuming and very inaccurate. With this in mind, we combined two different methods for the in-situ measurement of the solid-bed ratio: Analyzing pressure data and ultrasound reflection signals at different axial positions. These methods are more useful to investigate the melting behavior over the screw channel.