Online Resource
Visit
www.metalcastingdesign.com/content/category/20/49/314/ for articles on all of the major casting alloys, and see how they compare to their wrought counterparts.
cases we water-cool those chills,” Weiss said. According to Weiss, Eck also uses
more extensive risering to achieve the steeper thermal gradients that are necessary to produce the stron- gest cast version of the wrought material possible.
Clearing the Way for Casting Metal casting purchasers often ask
their suppliers to produce wrought products. They simply aren’t aware the materials aren’t available in the form of a cast metal component. The designer knows only the properties he or she desires. So when a metalcaster embarks on
a mission to cast the alloys, it fi rst must show the materials in fact offer com- parable mechanical properties to tra- ditional wrought alloys. The next step would be to have the alloys cleared
by manufacturing’s many governing bodies and standards committees. The materials can’t just be passed off to customers as exact equivalents to wrought chemistries. “There is no shortcut in terms of
developing the alloys,” Montes said. “It isn’t starting over—you borrow some things from the wrought materials, so it is a nice starting point. But it only gives you the ballpark.” Johnson Brass has succeeded in
having its materials recognized in the Aluminum Association’s Pink Sheets, but the alloys are narrowly defi ned as centrifugally cast approximations of wrought chemistries. The developers of other types of cast-wrought alloys will have to go through similar steps to obtain recognition of their alloys. “The alloys are going to have to be
fully characterized as casting alloys,” Weiss said. “What we don’t know yet
is how the fatigue performance differs from the wrought to the casting and what kind of corrosion issues they might have. It depends on the applica- tion, but certainly before I would use it on something I was designing, I would need more information.” Still, Weiss agrees with Shankar
that the alloys could be available in cost-effective, production-ready forms in two to three years. His re- search team has shown that in some cast aluminum equivalents, yield strengths in the 70 ksi range can be achieved, better than any of the traditional cast alloys. The experiences of Johnson Brass
don’t suggest quite as rapid a timeline. While the company began trying to perfect its properties and gain certifi - cation for its alloys when Montes was 28, he’s now 38, and only in the last half decade has it found a way to make the proprietary alloys understandable for customers. “After we went to the Aluminum
Association four to five years ago, things started happening quickly,” Montes said.
METAL
38 METAL CASTING DESIGN AND PURCHASING
SEPTEMBER/OCTOBER 2010
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