Automated pouring at Signicast Corp., Hartford, WI.
|IBC Engineered Materials relocated its investment casting foundry earlier this year, and is producing a series of aerospace components and commercial products in beryllium-aluminum alloys — about which details are well guarded.|
|Signicast’s Module 4 was completed in 2006, and produces investment castings in low-alloy carbon steel, tool steel, and 300 and 400 series stainless steels. It is the most highly automated installation at the Hartford, WI, plant, though a new module planned for a 2013 start may exceed its capabilities.|
| Signicast’s Module 5 at Hartford, WI, is a self-contained machining, assembly, vibratory tumbling, and painting operation. Investment castings are delivered there by an automated system for finishing, according to the requirements of the order. The current expansion at the Hartford, WI, ferrous foundry will include a new secondary processing operation. |
Metalcasters understand each other. The industry brings together individuals for what often is a lifetime vocation. They know each other through their work, and they know the problems and challenges of the work that their colleagues do. There aren’t too many secrets among them. There is an exception though in the field of investment casting, where even simple questions are met with long pauses and stock replies: “I can’t really get into that,” or, “That’s proprietary information.”
It’s no secret that investment casting is thriving. For an industry with ancient roots, it is a window to the future. And while the technique is not new, advances in process control and material science have elevated investment casting to the high-value realm — making investment casters the frequent object of investment experts. Private-equity acquisitions of Triumph Precision Castings and Consolidated Precision Products Corp. are recent examples of this, both firms being manufacturers of aerospace components.
The importance of such capabilities makes the secrets of investment casting even more valuable, valuable enough to drive new capital investments. Chromalloy Corp., the producer of aircraft engine components, started a new, $30-million foundry in Tampa late last year on the impetus of rising demand from the commercial aircraft market, and with its sights set on the industrial gas turbine market, too. Soon, an adjacent ceramic core plant will be added.
Generally, investment casting is a simple process: Working from a master pattern, a mold is made from which a series of wax or ceramic patterns are produced. These patterns are arranged into one complex assemblage, and this cluster is given a refractory ceramic coating. Once the requisite coating thickness is achieved and the ceramic is hardened, the wax is burnt out from the shell molds and the latter are preheated in preparation for filling with molten metal. Pouring may be done in various ways, and solidification may require special production or handling steps, such as vacuum processing. Finished castings are removed from the shell by vibration, blasting, chemical treatment, or other methods.
Obviously, investment casting allows for lots of variables in technique, and the specifics of metallurgy or ceramic formulation, or the vacuum or pouring processes, are among the secrets to success.