Some aspects of injection‐molding dynamics were studied using a laboratory injection‐molding machine operated under the control of a microprocessor‐based servocontrol system. Two types of experiments were performed: deterministic tests which introduced step changes in the servovalve opening and stochastic tests using pseudo‐random binary sequence (PRBS) perturbations of the servovalve. Deterministic models were written for the hydraulic and nozzle pressures which were in good agreement with the experimental data. A stochastic transfer function‐noise model was obtained for the nozzle pressure, but an adequate model was not found for the hydraulic pressure. The agreement between the nozzle pressure stochastic model and the corresponding step test model was satisfactory.

A mathematical model of the dynamics and heat transfer of the film embossing process has been developed. The thermal analysis around the preheat roll is determined from an unsteady, two‐dimensional heat conduction equation along with appropriate boundary conditions by neglecting the curvature of the preheat roll and choosing a Lagrangian reference frame. The heat transfer occurring between the preheat roll and the embossing rolls is based on a one‐dimensional analysis, including both convective and radiative effects. The deformation occurring in the nip region is analyzed for two different situations. For the case where the surface features are small in comparison with the film thickness, a modified one‐dimennsional calendering analysis is given, accounting for the irregular geometry of the embossing roll surface. For the case where the polymer does not make complete contact with the surface of the engraved channel, the local deformation is determined by means of a simple one‐dimensional cavity filling model. The required pressure distribution is determined by means of a simple one‐dimensional cavity filling model, The required pressure distribution is determined by means of a conventional calendering analysis. The analysis for the case of a Newtonian and power‐law model is presented in detail. The model yields qualitatively correct results and is computationally simple.

Film embossing is a mechanical process in which ajlat film is transformed into an

The modification of the injection-molding machine, incorporating additional filters, an accumulator, and a servovalve, was shown to reduce the peak cavity pressure variations, in as much as the variations using the microprocessor system were random in comparison to the variations using the normal mode of operation, which exhibited nonstationarity and autoregressive behavior. If the peak hydraulic pressure could be randomized, then the peak cavity pressure variations also would be random. No closed-loop control would be needed to control the peak cavity pressure.

Film embossing is a mechanical process in which a flat film is transformed into an embossed product. During the process, thermal and stress fields are applied Lo the polymer, causing changes in the microstructure and physical dimensions of the material. The engineering analysis of the process requires the study of various aspects relating to the characterization of the microstructure before and after embossing, A variety of techniques were employed to characterize the properties and microstructure of the embossed film in relation to: crystallinity, orientation, mechanical properties, and dimensions of the embossed films. The thermal treatment of the polymer film was shown to be the most significant factor in the process. By controlling the thermal treatment of the film, it is possible to manipulate the properties and dimensions of the embossed film. The important aspects: influencing thermal treatment include the radiation heater temperature, preheat roll temperature, line velocity, and film thickness. The initial film orientation and embossing pressure have a minor effect on the final properties of the embossed film. The main effect of the embossing pressure is on the bulk thickness of the embossed film.