This page contains a Flash digital edition of a book.
interesting to note that this flow pattern is liable to produce oxide inclusions because of the superposition of the two “re- turn” metal streams with their corresponding ones flowing underneath, whereas the inclusion of gas bubbles seems to be much less likely. Later simulations revealed an analogous flow effect (featuring only one metal stream) for the unilat- eral (B0) plate. For the A1 and A2 configurations, similar entrainment events, but of much lesser extent were noted.


Temperature


To locate areas of possible early solidification within the plate cavity, the temperature at the end of filling provides relevant information. In Figure 3, configuration B, it is seen that the coolest area, approximately below 615C (1139F), is located within the center area of the B plate. It will be seen in later dis- cussion that this was the approximate location of the conflu- ence weld in each of the three B plates produced at the slower filling rate. This area will also be of concern for the results of the Material Trace section as it determines the separation be- tween the metal fronts coming from the two different ingates. Configurations A2 and A1 of Figure 3 show the first areas of solidification start along the outer edges of the plate cavity, especially in the A2 design and at the end of filling, the hottest metal will be along the vertical ingate paths.


Material Trace


A main focus of this work is the monitoring of the melt flow from the ingates, so it is important not only to know the speed at which the melt enters the plate cavity and rises but also the path the metal follows from each individual ingate. The scale in the following images varies depending on the number of ingates, as the metal from each ingate is delineated with a different color. In Figure 4, configuration B, in the center area near the feeder, there is a definite separation between the metallic fronts, with little to no mixing of the two. This result corresponds with the temperature result discussed previously, as well as with the confluence welds observed, which will be examined in the Confluence Welds section. In the event there is little or no mix- ing of the streams from the various ingates during filling, there is an increased possibility of the occurrence of a solidification defect in this area, resulting in sites prone to failure initiation.


There is more apparent mixing of the metal in the designs filled from the bottom of the plate cavity, as is shown in the A configurations in Figure 4. In the A1 and A2 configura- tions, versus the B, there are few areas in the center of the plate in which the original ingate color is still dominant, as new colors have formed indicating continuous mixture of liquid metal during filling.


B


A2


A1


Figure 3. Temperature results at the end of the plate cavity filling for the three configurations: B; A2; A1 (the scale in gating configuration B, applies to A2 and A1 as well).


B


A2


A1


Figure 4. Material trace results of the three configurations. (Scale corresponds to ingate number assignment): B; A2; A1. The light blue color designates metal that is present in the gating system, whereas yellow, red, and dark blue designate metal that has flown to the plate cavity through the ingates.


International Journal of Metalcasting/Spring 2012 69


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91