Plastic part filling was mostly the only focus in past simulations. Normally, the runner is simplified during analysis with 1D beam elements and numerical assumptions, such as velocity and pressure, as the inlet condition of melt entering part from runner end. Currently, as runner simulation is getting more and more attention, 3D runner mesh technology has been developed to deal with the filling process not just in the part but also in the runner area. Filling behavior and temperature variation inside the runner help on analyses of issues such as the uneven temperature distribution induced by shear heating and the flow imbalance in multi-cavity molds.
Mesh quality is essential for accurate simulation of the melt behaviors inside the 3D runner. Moldex3D users before had to prepare 1D pass curve with 2D cross-section mesh, and then create 3D runner mesh through sweep or other tools for solid mesh generation. Runner Wizard in Moldex3D Designer, on the other hand, can be utilized for simple runner design to semi-automatically generate 3D runner mesh with wireframes and runner parameters such as diameter. These tools are essential in mold filling simulation and will significantly affect the analysis results.
However, as the molding technology continuously advances, we see more and more varied and complicated runner designs. These require significant time and effort for users to build models for numerous and sophisticated 3D runner mesh.
In order to help users quickly create runner models with 3D mesh, new mesh technology for high-quality runner models has been developed in Moldex3D R15. New features such as hexa-based solid mesh, node types and node preview are included and will be introduced respectively in following sections.
New Template (Hexa-based) for Runner System
Hexa-based runner mesh enables users to attain required mesh layers with less element amount (Fig. 1). It is built with high-resolution and high-quality mesh, and can also help reduce operation and analysis time.
Fig. 1 The solid runner mesh in Moldex3D Designer R14.0 is based on Prism (left),
and the solid runner mesh in Moldex3D Designer R15.0 is based on Hexa elements
More Connecting Node Types
At the connection of the runner curves, the available option of node types will be automatically provided for users to choose according to the curve amount, angles and runner types. In Fig. 2, the T-shape connection by 3 lines and its 3 node types, node preview and solid mesh results are shown as an example.
Fig. 2 The runner simulation technology can automatically interpret available node types for users to choose
Real Time Node Preview
As mentioned, this new runner mesh technology provides real time node preview, so users do not have to wait until the end of mesh generation. The runner mesh result will perfectly match to node setting as preview without deformation. Hexa-based mesh will be generated for common runner layouts, and BLM (Boundary Layer Mesh) will be generated for other more complicated runner layouts.
Fig. 3 shows different runner types and their runner curve parameters, runner node preview and hexa-based mesh results. Moldex3D R15 also allows users to choose common gate node types for mesh generation (shown in Fig. 4).
Fig. 3 The first row shows the results of runner curve parameter settings; the second row shows the node preview of the hexa-based runner mesh; the third row shows the mesh generation results
Fig. 4 The first row shows the results of gate node parameter settings; the second row shows the node preview of the hexa-based gate mesh; the third row shows the mesh generation results
As shown in Fig. 5, with the new hexa-based runner mesh, there will be less mesh element but better mesh quality for more accurate analysis results.
Fig. 5 With the new hexa-based runner mesh, the mesh elements will be less, and better mesh quality can be attained
With Moldex3D R15 high-speed and high-quality mesh technology, the high-resolution hexa-based mesh can be generated automatically.The mesh model can perfectly meet the original runner design with high analysis accuracy. Complicated runner design are realized with significant reduction in time and cost.