Review the press displacement results of the compression molding process to determine the quality of the part

In this task you review the press displacement results of the compression molding process. For this exercise you evaluate if the process settings are adequate to obtain the part thickness within 3% of the design thickness which is the tolerance set for this part.

To review the Press displacement: XY plot:

1. Click Press displacement:XY Plot in the Study Tasks list.

   

   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.

   • 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. The calculated press open distance is 26.5 mm while the one reported in the result is 26.26 mm which are close.
   • The objective is to run a 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.
2. Use the following equation to determine how closely your final molded part thickness approximates your design thickness. Design thickness + press open distance (input) - press displacement (result) = final molded part thickness (which should be equal or very close to the design thickness).
   • Design thickness =
     • Tip. Use the measuring tool to determine the part thickness.
   • Press open distance =
     • Tip. Look up in the Log the value for “The calculated press open distance” located in the Compression Control settings.
   • Press displacement =
     • Tip. You can use the Examine tool to obtain this value from the Press displacement: XY plot or look in the Log and use the final value for Press displ (mm) listed at the end of the Packing analysis table.
3. Calculate the final molded part thickness

   Design thickness + press open distance (input) - press displacement (result) = final molded part

   ________+_______ - ________ = _________

4. Calculate the difference in percentage

   [(Final molded part thickness- design thickness)/design thickness] *100

   [(_____ - ______)/_____] * 100 = _______%

5. If the part thickness is supposed to be within 3% of the design thickness, did the results show this?

   Tip: For this part the part thickness is over 4% than the design thickness so the part is not within specifications.

Click the Next topic link below to move on to the next task of the tutorial.