Plastic flow simulation made easier through CAD-CAM-CAE integration

The current global competitive environment means that mould makers often do not have the luxury of carrying out bench tests and moulding trials, they usually rely on ‘past experience’. For this special feature, Vijay Kudchadkar provides an insight into how plastic flow simulation is made easier through CAD-CAM-CAE product integration.

Historically, flow simulation software has had limited modelling capabilities and certainly no machining capabilities. Typically, parts and moulds designed in CAD software would have to be transferred to the flow simulation software. In a traditional design optimisation study, the designer would have to go back and forth several times between the CAD and flow simulation software to fully optimise the part and mould design. Once the study was completed, the optimised design would then have to be transferred to the CAM solution for manufacture. This approach adds hours (if not days) to the mould design project, especially if the designer does not have the CAD software from which the file originated. Until recently, this approach has been the only option available to the tooling industry.

A new approach has been developed by Vero Software where the plastic flow simulation software has been fully integrated within the CAD/CAM environment. This article discusses how this new CAD-CAM-CAE integration reduces the time and effort in preparing & running a flow simulation.

Improved CAD tools
Importantly, the CAD integration allows the engineer to construct the part and tool design from scratch and also make critical part changes where necessary. Simulation results such as pressure, temperature at the end of cooling, warpage, etc. would indicate if the part model would be acceptable or not as a final component. Based on these results, important part attributes such as taper, wall thickness, ribs, bosses, diameters and radii can all be modified. Damaged surface models can also be repaired and closed to a solid using internal CAD tools.

The CAD tools can also be used to modify the runner layout, runner dimensions, gate dimensions, cooling layout and cooling dimensions inside the mould design. A common challenge faced by mould makers is to produce acceptable parts with minimum cycle time, and as cooling time accounts for most of the cycle time, this is a key area where productivity can be improved.

Increased import options
The CAD-CAM-CAE integration not only allows the designer to construct the part and mould inside the same environment as the flow simulation software, but it also allows the designer to read files in almost any CAD format. The analyst can now directly work with the native CAD model and no longer has to struggle with IGES or tessellated geometry files.

Easier mesh preparation
The finite element mesh can be prepared directly on native CAD models - This approach dramatically reduces the amount of manual work required to create a valid mesh as opposed to working with IGES or STL data. It is not uncommon to spend hours repairing and generating acceptable mesh geometry for flow simulation. Importantly, the integration of the mould design also allows the designer to create a mesh for the mould components and included them within the flow analysis including the ability to simulate the plastic behaviour inside hot runners, for example, pressure drop and residence time.

Development of new functionality
The integration of CAD/CAM technology provides a platform for development of new dedicated applications that impact on the simulation results.

Runner to flow technology
The runner system is a critical part of the analysis and is often left out of the simulation as typically this is a laborious task to create the relevant data inside flow simulation software. Runner to flow functionality significantly reduces the steps involved in preparing a mesh on the runner system. This functionality reads the 3D mould design and looks for features that could possibly form the runner system. It prompts the user to select the start and end point of the runner system and then proceeds to automatically create the mesh for the runner system and adds the data to the moulding set-up parameters.

Cooling to flow technology
For cooling, as similar concept exists where the mould design is analysed and the cooling channels and components such as baffles and fountains are automatically extracted and included within the flow simulation. The user is prompted to select the start and end point of the cooling circuit and the software automatically creates a mesh for the cooling circuit.

Faster transfer to machining
In this CAD-CAM-CAE approach, all the relevant changes for improving the design are made directly to the mould model. The final design can be issued for machining eliminating any concerns about data loss through additional translations. Knowledge based feature recognition will automatically select features directly on the solid geometry and create reliable milling and drill cycle toolpaths.

Summary
The integration of CAD-CAM-CAE technology allows the tool maker to design the part, mould tool, run flow simulation analyses and manufacture the tool in the same software environment. Flow simulation is moving towards being part of the CAD/CAM family which significantly reduces the steps involved in running a successful flow analysis study. These new developments in flow simulation software, combined with reduced software costs and faster simulation times should encourage tool makers to include flow simulation in their product development cycle. Basing a tool design on a preventive flow analysis can detect potential manufacturing issues – such as welding lines, air traps, best gate location, etc, providing the maximum possible time frame for a corrective solution - This is only made possible through an integrated CAD-CAM-CAE analysis.

Back...