We’ve found that image analysis techniques are interesting for developing manufacturing routes for castings. William Warriner is developing all of the routines shown below to be used in his PhD work. For example, watershed segmentation of the solidification profile of a casting geometry is quite illustrative. Below, at left is a component, shown transparent, and at right are the watershed segments of the component’s solidification profile overlaid on the component. Essentially the segments tell us what regions of the casting can be fed by the same feeder or group of feeders. Feeding will occur from segment boundaries where solidification begins and proceeds the thickest section.
Using attributes of each segment and the solidification profile, we can apply known feeder design guidelines to generate feeder geometries. Below are the feeders generated from the segments. In practice, feeders that interfere with geometry can be replaced by side-attachment feeders, or by gating directly to the location of the feeder. In the meantime, it is still worth visually reporting that a feeder is required.
Several of the sections are close and it is believed that number of feeders is correlated with increased cost and with decreased ease of manufacturing. One goal could be to decrease the number of feeders. One way to do so is to provide connections, or feed pads, between segments. Creating feed pads can be accomplished by drawing a solid tube between the feeder locations of neighboring segments. Below at left are the connecting tubes overlaid on the component. At right is the same image with greater visibility of the tubes.
One strategy for reducing the number of feeders is to cluster their segments by proximity. From the perspective of connector tubes, that would mean removing longer tubes and retaining shorter ones. Below at left are the original set of tubes, and at right are the reduced set. Note that currently there isn’t an obvious quantitative metric for doing this without human intervention. The tube removal process here is based purely on human intuition and is intended to illustrate the usefulness of the tubes.
Now that the connector tubes have been pared down to several clusters, it should be possible to reduce the number of feeders so that each cluster is fed by only one feeder. An example, purely for illustration purposes, is shown below. The number of feeders has decreased from 16 to 6. Note that the connector tubes are quite crude, and would almost certainly not be able to be implemented as they appear here.
A casting designer would have to work closely with a product designer to rework the original geometry. They would likely incorporate the connector tubes as wall thickness changes in appropriate locations. Any changes would have to avoid altering features that must remain as-cast. There is also the consideration of avoiding more net-shape machining by adding material in locations where machining is not required.
Dr Monroe Thoughts 