Press displacement:XY Plot result

The Press displacement:XY Plot result shows the distance the press moved, measured from the reference (initial) location, to the final location at the end of the compression phase, when the mold-cavity space has been reduced (compressed), displayed on an XY plot of distance versus process time.

It is generated from an Injection-compression molding analysis.

Using this result

Because the mold open stage is not considered in this analysis, there is no backward movement of the press. The minimum value of press displacement is zero and the maximum value is the press open distance. When the press displacement reaches the maximum value, the press will not move forward any more. It will remain stationary until the end of the process.

Note: The number of time steps plotted on the XY graph is determined by the input specified for the Number of regular results in Filling phase and Number of regular results in Packing phase options.

To specify the numbers of regular results to output, click Process Settings (Home tab > Molding Process Setup panel > Process Settings), if necessary click Next to access the Compression Settings page, click Advanced options, click Edit in the Solver parameters group, and select the Intermediate Output tab.

Things to look for

The objective is to run an Injection-compression molding analysis that generates a press displacement result that is equal (or as close as possible) to the value you specified as input for the press open distance. When these values are equal, the thickness of the molded part will be the same as the specified design thickness.

If the press displacement result is not close enough to the press open distance, you can adjust the input, re-run the analysis, and re-examine the results.

Use the following equation to determine how closely your final molded part thickness approximates your design thickness.

For example, suppose:

  • 0.60mm = Design thickness
  • 0.59mm = Press open distance
  • 0.57mm = Press displacement
Note: Design thickness + press open distance (input) - press displacement (result) = final molded part thickness.
The final molded part thickness would be 0.62mm. The final molded part thickness is 3.3% larger than the design thickness. If this error is too great, you can try adjusting one or more of the following process settings and re-run:
  • Reduce the Press open distance.
  • Reduce the Press waiting time so that the press can close earlier before too much material is injected into the cavity.
  • Increase the Press speed so that the press can close earlier.
  • Increase the Press compression force so that the material can be further compressed.
  • Keep the injection location open after packing so that extra material can be squeezed out.
  • Reduce Velocity/pressure switchover by %volume so that less material will be injected into the cavity.
  • Increase the Fill time (to reduce the flow rate).
Parent topic: Compression molding analysis results