Adjust warp constraint positions according to the mold shrinkage allowance

For several industrial products, such as automobiles, aircraft, and home appliances, maintaining precise dimensional tolerances is critical once injection molded components are integrated into an assembly. Shrinkage and warpage induced by the injection molding process could potentially cause the manufactured part to deviate from its intended shape and size. For flexible plastic parts, forces can be applied during assembly to realign the part connection points to their nominal position. In some cases, the warpage issues of injection molded components can be rectified once they are constrained in assemblies. Conversely, flat components may become distorted during assembly due to unexpected shrinkage magnitude resulting from the injection molding process. Thus, predicting the deformation and stress of injection molded components post-assembly can be a valuable design tool for detecting assembly issues and enhancing the design.

In practical scenarios, mold makers need to consider the process-induced shrinkage of the material when manufacturing the mold. A scaled-up model is typically used for injection molding simulations to verify the final part shape after shrinkage and warpage relative to the designed part dimensions and tolerances. If the Cavity dimensions include mold shrinkage allowance. Adjust constraint positions automatically option is selected, the solver will automatically adjust the warp constraint positions applied to the scaled-up model based on the mold shrinkage allowance to reflect their actual positions in the designed dimensions. The solver subsequently calculates the final deformation of the injection molded part post-assembly and its deviation from the original part design.

Prerequisites

Before proceeding with this task, it is assumed that you have:

• Imported a model whose dimensions have been expanded to account for mold shrinkage allowance;
• Created a mesh for the model and verified it for errors;
• Designated the injection locations;
• Included warp as part of the analysis sequence.

Steps

1. Define warp nodal constraints representing the forced assembly or fixing points of the part after molding.
   1. Click (Boundary Conditions tab > Constraints and Loads panel > Constraints > Fixed Constraint).
   2. Use the cross-hairs to select the mounting node(s) for which you want to set the constraint.
   3. Select Warp Analysis or Stress and Warp Analysis from the Use constraint in drop-down menu.
   4. Click Apply. An appropriate constraint symbol will be displayed at each location you have constrained.
   5. Click Close to close the dialog.
2. Click (Home tab > Molding Process Setup panel > Process Settings) then click Next until the Warp Settings page.
3. Select the Cavity dimensions include mold shrinkage allowance. Adjust constraint positions automatically in the dialog.
4. Specify the Mold shrinkage allowance following Cavity dimensions include mold shrinkage allowance. Adjust constraint positions automatically using the factor you used to scale up the designed dimensions.
5. Click Finish to close the Process Settings Wizard.
6. Run the warp analysis.
7. Once warp analysis completes, you can view the Deflection, all effects result which shows the final part shape after it is mounted into adjusted assembly positions.