Flow simulation data can significantly reduce the time until the real sampling of a tool and avoid expensive tool modifications. The prerequisite is that the development partners work on the project in a centralized, simultaneous workflow instead of sequentially and contribute their know-how simultaneously.
Oerlikon HRSflow, part of Swiss technology group Oerlikon and its polymer processing solutions division, is based in San Polo di Piave/Italy and specializes in the development and production of hot runner systems for the injection molding industry.
Recently, the company formed a joint project with chemical company Borealis and injection molding specialist Engel formed a joint project which used the example of a demanding mold to show how successfully injection molding parameters can be improved in the simulation and transferred directly to the machine as an initial setting proposal, provided that all relevant data of the injection molding machine, the processed material as well as the hot runner system and other components are available.
The simulation was carried out with the aid of Moldflow, using the example of a family mold with three cavities and a weight difference of 1:11 from the smallest to the largest component. Engel provided a duo injection molding machine, detailed values, for example on the geometries of the nozzle used, as well as the sim link data interface for the direct connection of Moldflow to the CC300 control unit of the injection molding machine. Borealis provided data on the flow behavior of its Daplen EE001AI polypropylene, and Oerlikon HRSflow contributed a servo-driven eight-cavity hot runner system that allows the volume flow to be controlled and thus each cavity to be filled individually.
In the traditional process, the parties involved do not discuss possible causes of faults and remedial measures until after sampling has been completed. In the project described here, optimization with regard to temperature control, injection characteristics and all other pressure and time-related injection molding parameters began jointly and immediately at the beginning of the simulation. The parameters determined in several iteration steps were then transferred to the machine via sim link. This data exchange between simulation software and injection molding machine could take place in both directions. It thus also enabled the analysis of process data, which in turn provided potential for process optimization. Access to sensitive design data is not necessary. The real production start-up underlined the high precision of the settings found via Moldflow. The real filling behavior and the positioning of the weld lines matched the simulation 100%. The warpage behavior of the largest part, the door trim measuring around 600 mm x 400 mm, was predicted to within ±2 mm, and the dimensions across the diagonal of over 650 mm were maintained with maximum deviations of only 0.04 %. After a few optimization steps and without major manual readjustment, all three molded parts met the quality requirements.
This joint project has not only shown that real production can run almost identically to the simulation, but also opens up potential for more sustainable production. For example, it is possible to see in the design phase whether a machine is suitable for the intended product or whether energy can be saved and production efficiency increased by using a smaller machine. In addition, the setting data suggestion developed in the simulation reduces the number of necessary setting cycles. This leads to fewer rejects and lower energy consumption during sampling.
