Weld Line Prediction in the 3D Flow Solver

Transcription

1 AUTODESK MOLDFLOW INSIGHT 2011 VALIDATION REPORT Weld Line Prediction in the 3D Flow Solver Executive Summary This document presents a validation of the Weld lines result predicted by the 3D Flow solver in Autodesk Moldflow Insight In the 2010 release, weld lines were predicted by 3D analyses of the thermoplastic injection molding process using Autodesk Moldflow Adviser but were not predicted by 3D analyses using Autodesk Moldflow Insight. Now, the Weld lines result has been made available for all 3D processes in Autodesk Moldflow Insight 2011, including thermoplastics injection molding, thermoplastics overmolding, gas-assisted injection molding, reactive molding, microchip encapsulation and underfill encapsulation. Also, due to algorithm improvements, the 3D Weld lines result predicted by Autodesk Moldflow Insight 2011 (and Autodesk Moldflow Adviser 2011) analyses in general is better than that predicted by Autodesk Moldflow Adviser 2010, Release 2. In this report, results from Autodesk Moldflow Insight 2011 analyses are presented and compared with results from Autodesk Moldflow Adviser 2010, Release 2, where possible. Weld Line Calculation If two melt fronts meet at a small angle (for example, 135 degrees or smaller), a weld line is formed. The definition of meeting angle is illustrated in Figure 1. In Autodesk Moldflow Insight 2011, several improvements in the weld line calculation methods have been made to reduce the number of false weld line predictions and failure to predict legitimate weld lines. In comparing weld line results from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011, it should be noted that the flow-front advancement method has changed between the two releases. In Autodesk Moldflow Adviser 2010, Release 2, a Volume of Fluid method is used, whereas in Autodesk Moldflow Insight 2011, a Level Set method is used (refer to the Autodesk Moldflow Insight 2011: Flow Front Advancement in the 3D Flow Solver validation report for details). Some results of weld line calculations from Autodesk Moldflow Insight 2011 (and comparisons with Autodesk Moldflow Adviser 2010, Release 2 for some cases) are presented in the next section.

2 Figure 1: Definition of meeting angle, where two melt fronts meet at an angle of ϴ. Test Cases In this report, results from five cases will be presented, four of which use thermoplastics injection molding process and one of which uses the underfill encapsulation process. For the thermoplastics injection molding cases, results from Autodesk Moldflow Insight 2011 are compared with those from Autodesk Moldflow Adviser 2010, Release 2. Mouse case The fill time plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 are shown in Figure 2 and are quite similar. The respective weld line plots are shown in Figure 3. For this case, both Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 predict all legitimate weld lines. However, Autodesk Moldflow Adviser 2010, Release 2 predicts several false weld lines, whereas Autodesk Moldflow Insight 2011 predicts almost no false weld lines. 2

3 Figure 2: Mouse case Fill time plot from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight

4 Figure 3: Mouse case Weld lines calculated by Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight Demo4 case The fill time plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 are shown in Figure 4. In this case, the fill time plots are somewhat different, which is due to the change in flow front advancement method described previously. The weld line plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 are shown in Figure 5. Please note that the injection location is near the center of the part for this case. Also, the rectangular area in the left center area has smaller thickness than the surrounding area. The slower flow advancement in this depression results in a weld line. We also expect to have three major weld lines behind the holes. Both Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 predict all legitimate weld lines. However, Autodesk Moldflow Adviser 2010, Release 2 predicts many false weld lines. On the other hand, Autodesk Moldflow Insight 2011 predicts almost no false weld lines. 4

5 Figure 4: Demo4 case Fill time plot from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight

6 Figure 5: Demo4 case Weld line plots from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight Peace Sign case For this case, the fill time plots from Autodesk Moldflow Insight 2011 (at three different time steps) are compared with experimental results in Figures 6 8. This comparison is made because accurate weld line prediction requires accurate flow front shape prediction. As can be seen, the experiment and simulation results agree relatively well for this case. The fill time plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 (Figure 9) are only slightly different. The weld line plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 are shown in Figure 10. For this case, we expect four weld lines where melt fronts meet at a small angle. Autodesk Moldflow Adviser 2010, Release 2 predicts three of the legitimate weld lines but misses 6

7 one legitimate weld line. It also predicts a few false weld lines. On the other hand, Autodesk Moldflow Insight 2011 predicts all legitimate weld lines and predicts only one small, false weld line. Figure 6: Peace Sign case Short shot from experiment and Autodesk Moldflow Insight 2011 simulation, stage 1. 7

8 Figure 7: Peace Sign case Short shot from experiment and Autodesk Moldflow Insight 2011 simulation, stage 2. 8

9 Figure 8: Peace Sign case Short shot from experiment and Autodesk Moldflow Insight 2011 simulation, stage 3. 9

10 Figure 9: Peace Sign case Fill time plots from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight

11 Figure 10: Peace Sign case Weld line plots from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight Box case This case is for a simple box with injection locations near the four corners. The fill time plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 (shown in Figure 11) are similar. 11

12 The weld line plots calculated from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight 2011 are compared in Figure 12. From the flow pattern, we expect to see four weld lines along the lines where the melt fronts from the four injection locations meet. Autodesk Moldflow Adviser 2010, Release 2 predicts three weld lines, but misses one legitimate weld line. Autodesk Moldflow Insight 2011 predicts all four weld lines correctly. Figure 11: Box case Fill time plots from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight

13 Figure 12: Box case Weld line plots from Autodesk Moldflow Adviser 2010, Release 2 and Autodesk Moldflow Insight Underfill Encapsulation case The fill time and weld line plots calculated from Autodesk Moldflow Insight 2011 are shown in Figures 13 and 14. For this case, there should be one weld line behind each hole. As can be seen in the weld line plot, most legitimate weld lines are predicted by Autodesk Moldflow Insight

14 Figure 13: Underfill Encapsulation case Fill time plot from Autodesk Moldflow Insight Figure 14: Underfill Encapsulation case Weld line plot from Autodesk Moldflow Insight

15 Summary of Results As shown by the example cases described in this document, the weld line predictions from Autodesk Moldflow Insight 2011 produce fewer false weld lines and more legitimate weld lines compared to Autodesk Moldflow Adviser 2010, Release 2. Revised 9 March Autodesk, Inc. All rights reserved. Except as otherwise permitted by Autodesk, Inc., this publication, or parts thereof, may not be reproduced in any form, by any method, for any purpose. Trademarks Autodesk and Moldflow are trademarks or registered trademarks of Autodesk, Inc., in the USA and/or other countries. All other brand names, product names, or trademarks belong to their respective holders. Disclaimer THIS PUBLICATION AND THE INFORMATION CONTAINED HEREIN IS MADE AVAILABLE BY AUTODESK, INC. "AS IS." AUTODESK, INC. DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE REGARDING THESE MATERIALS. 15