Shrinkage

Manually specify Part Shrinkage

You can make unique percentage adjustments to the mold dimensions of each individual part to accommodate the shrinkage of the polymer as it cools. This process is useful if the parts in a family mold are of different sizes and/or thickness.

Note: It is not possible to set both Part and Mold shrinkage.

1. Ensure that a material is selected.
2. In the Core/Cavity tab, click Part Shrinkage. The Shrinkage dialog box displays. On the Set tab, the default shrinkage values are taken from the Autodesk Moldflow material database.
3. Edit the Shrink Percentages.
4. Click OK or Apply. The Shrinkage node beneath the specified part in the Mold Design browser updates.

Manually specify mold shrinkage

Apply a global percentage adjustment to all the plastic parts within a mold.

Note: It is not possible to set both Part and Mold shrinkage.

1. Ensure that a material is selected.
2. n the Mold Layout tab, click Mold Shrinkage. The Shrinkage dialog box displays. On the Set tab, the default shrinkage values are taken from the Autodesk Moldflow material database.
3. Edit the Shrink Percentages.
4. Click OK or Apply. The Shrinkage node beneath the mold assembly in the Mold Design browser pane updates.

Obtain suggested part shrinkage values

You can make unique percentage adjustments to the mold dimensions of each individual part to accommodate the shrinkage of the polymer as it cools. This process is useful if the parts in a family mold are of different sizes and/or thickness.

1. Ensure that a material is selected, and at least one gate location exists for the part.
2. On the Core/Cavity tab, click Part Shrinkage. The Shrinkage dialog displays. On the Suggest tab, enter the packing profile data into the table provided. The left-hand column represents the time in seconds. The right-hand column represents pressure values.
3. Optional: Click Plot to preview the profile you have entered.
4. Optional: Click OK to close the plot profile.
5. Click Start to launch the Shrinkage analysis. On completion of the analysis the Summary dialog box displays. In the Mold Design browser, an analysis results node displays.
6. Click OK. In the Mold Design browser, beneath the specified part, the Shrinkage node updates.

Obtain suggested mold shrinkage values

Mold shrinkage analysis provides unique shrinkage analysis results for all parts within the mold design. It takes, into account the effects of the feeding system, which includes the sprue, runners, and gates.

1. Ensure that a polymer material is selected, and all parts in the mold assembly are connected through a suitable feed system including sprue, runners, and gates.
2. In the Mold Layout tab, click Mold Shrinkage. The Shrinkage dialog displays. On the Suggest tab, enter the packing profile data into the table provided. The left-hand column represents the time in seconds. The right-hand column represents pressure values.
3. Optional: Click Plot to preview the profile you have entered.
4. Optional: Click OK to close the plot profile.
5. Click Start to launch the Shrinkage analysis. On completion of the analysis the Summary dialog box displays. In the Mold Design browser, an analysis results node displays.
6. Click Cancel. in the Mold Design browser, beneath the Results node, the Shrinkage node updates.

View shrinkage analysis results

You can view the results of completed shrinkage analyses of a plastic part or a mold.

The distribution of volumetric shrinkage can then be used to determine whether shrinkage is linear, that is, roughly equal for the whole part.

1. In the Mold Design browser, beneath the Shrinkage results node, double-click the analysis result to view. The analysis result displays in the graphics window.
2. Use the viewing tools to investigate the result details.
3. Beneath the Shrinkage results node, select the Summary result to view the Summary dialog box.

Apply shrinkage analysis results

You can apply the results of completed shrinkage analyses of a plastic part or a mold.

Use the estimated shrinkage to apply a linear shrinkage allowance to the nominal part dimensions. New mold dimensions are then generated.

1. In the Mold Design browser, under the Shrinkage results node. click the Summary node.
2. In the Summary dialog box, click OK. A shrinkage allowance generates that increases the part dimensions to compensate for the estimated shrinkage.

Edit shrinkage values

You can edit shrinkage allowance values, but this action changes the mold dimensions and can invalidate any previously generated results.

The estimated shrinkage from the analysis summary is used to generate new mold dimensions by applying a linear shrinkage allowance to the nominal part dimensions.

1. In the Mold Design browser, right click the Shrinkage value to edit, and click Edit Feature.
2. A warning dialog box displays. If you click Yes, you change the shrinkage values and mark any dependant analysis results as out-of-date.
3. Either manually change the shrinkage values, or run a shrinkage analysis.

Delete shrinkage values

You can delete shrinkage allowance values, but this action changes the mold dimensions and can invalidate any previously generated results.

1. In the Mold Design browser, right-click a Shrinkage node, and select Delete.
2. A warning dialog box displays. If you click Yes, you delete the shrinkage values and mark any dependant analysis results as out-of-date.

Delete shrinkage analysis results

• In the Mold Design browser, under Results, right-click a Shrinkage node, and click Delete.