Here are some of the results from the simulation that can now be used to optimize the mold design : pressure drop, temperature change, shear rate, shear stress, runner system volume, part cooling time and clamping force estimation.

Using one or a combination of these results will help determine the final and optimal design of a mold.

Number of Nozzles
The pressure drop results can help determine if more drops are needed. If the pressure drop across the nozzle is high, more nozzles should be added to the design to reduce the injection pressure needed to fill the part.

Number of Cavities
For a multi-cavity or family mold, the pressure drop and runner system volume results also can help you decide the appropriate number of drops that will work in the design. Depending on the target for injection pressure, the number of cavities can be increased or decreased based on the pressure drops across the nozzles. If there is an issue of residence time of the material in the manifold, the runner system volume result can be used to calculate the number of shots in the manifold. You may decide to reduce the number of drops in the design if there are too many shots in the manifold.

Nozzle Locations
Once the number of drops has been finalized, you can start reviewing the locations of the drops in the mold. The FEA will then show the fill of the hot runner system and you can visually check if the hot runner system has a balanced fill based on the drop locations. Because the CAE model can be modified easily, moving the nozzles to a different location and then rerunning the FEA will help establish the best locations in the mold design.

Gate Sizing
One of the challenges in designing for a hot runner system is determining the proper starting gate size for the material. The pressure drop, shear rate and shear stress results at the gate will be used to determine the gate size. The gate diameter in the CAE model can be modified until favorable results are achieved.

Design for Varying Materials
Since the initial CAE model can be used to run the analysis independent of material selection, multiple simulations can be performed if different materials are being considered. This can help you optimize wall thicknesses at the gate, gate sizes and request part changes if needed.

Mold Cooling
Mold cycle time is critical for cost savings. The FEA on the hot runner system will calculate the cooling time based on material, mold and melt temperatures. It also will warn you if the cooling time will be too long based on the parameters. Because the FEA does not account for the actual cooling lines in the mold and makes some assumptions that there is minimal cooling for the part, this result will establish if more cooling may be necessary.

Press Tonnage Check
Using the clamping force calculation results is a good check to see if the press the mold was designed for will be adequate. Mold changes should be considered if this is an issue.