was going on inside an otherwise salable casting was not a common practice. Additionally, extracting tensile bars is expensive and typi- cally done on initial samples only when the customer is willing to pay for it. More commonly, coupon bars are attached to a casting, which can be pulled off without destroying the part to determine properties. The overall task of gathering all this information was beginning to look like it would have to wait until a more-feasible and less-expensive solution presented itself. Fortunately, sometimes larger


Eck Industries sectioned three large 206 castings to build a database of mechanical properties found at varying wall thicknesses.


apply everything you know, try not to over-promise and then hope every- thing turns out as planned. You try to avoid making tweaks after the initial casting samples are made, but such is the nature of developing a new casting project. Final properties are unknown, until they are known. Bars need to be pulled out of casting sections, and those results will show whether they meet or fail the requirements. Eck Industries


felt there had to be a better way. Simulation data sets for pre- dicting casting properties of more common silicon-based aluminum alloys, such as A356, exist, but not for 206. At a simulation software users meeting in Spring 2012, Eck Industries discovered this informa- tion could be created with simula- tion modeling.


Finding the Constants To get started, Eck Industries


would need to share a comprehensive study of actual mechanical properties.


30 | MODERN CASTING June 2013


Tose properties would help deter- mine the alloy constants required to plug into the equations used to predict mechanical properties. Because the metalcasting facility


had a large database of 206 mechani- cal property data, this first step seemed simple. However, the data needed to be gleaned from known


scrap castings sit around a few days because cutting them up for revert takes extra time. With a little dig- ging, Eck Industries came across the perfect candidates: three sequen- tially poured castings that were leftovers from another trial. The three large castings con-


tained all the potential information needed. Two were poured of B206, and one was a trial poured of A206. None had yet been heat treated, and all had failed at X-ray inspection. The castings were large, symmetri- cally round housings, and the gating system had likewise been designed symmetrically to fill into the outer perimeter. Unusual for 206, the walls of this casting varied from 0.375 in. to 1.75 in.


Design a gating system driven by customer property requirements.


wall thicknesses. Preferably, the bars would be captured from a wide range of casting wall thicknesses to contain an accurate range of predicted prop- erties. CAD files of these projects and their gating would be required to run casting simulations needed to fine-tune the dataset. Eck Industries had the CAD files


of several past projects. Unfortu- nately, many of them had consistent wall thickness. Cutting up produc- tion castings just to find out what


With care- ful planning, Eck proceeded to quarter each of the three castings. Personnel ran one of the quarter sections through the T7 heat treat-


ment process and ran another quarter section through T4 heat treatment. Staff also pulled raw (F) bars from one of the quarters, which was important because it would serve as the baseline for comparing the existing software algorithm for property prediction. One quarter of each casting was


left as a spare in the event additional trials or verification would be required. As the groups made their way through heat treatment, Eck carefully picked 10 bars to be pulled from the same areas of


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