2001 Conference Spotlights Engineering, Defect Elimination.

The 64th Annual AFS Wisconsin Regional Foundry Conference and Mini-Exposition in cooperation with the AFS Stateline, AFS Northeast Wisconsin and the Univ. of Wisconsin fired up at Milwaukee's historic Pfister Hotel on February 15-16. The theme for this year's conference was "Become Active in the Foundry Industry," and, over the course of a day-and-a-half, 36 speakers and panelists gave 30 presentations, and 77 foundry industry suppliers exhibited.

AFS President Donald Gaertner, Metalcasting Equipment, Inc., gave the featured keynote address at the first day's Leaders of Industry luncheon. His multimedia presentation addressed how to get others, particularly young people, interested in the foundry industry and the need to break down commonly held stereotypes about foundry work. The second day's luncheon speaker, Milwaukee Bucks Head Coach George Karl, spoke about the importance of maintaining a team focus, regardless of industry.

Presentations during the conference covered all metalcasting processes and metals. Following is a look at two of them, one a fresh approach to engineering and the other sound metallurgical advice.

Design Engineering

In a presentation titled "In Your Face Engineering," Rodney Burkhardt, Metal Technologies, Inc. (MTI), Milwaukee, discussed his firm's approach to the design engineer and purchaser, as well as the foundry-engineer relationship with cast component design. Burkhardt emphasized the importance of building a symbiotic relationship with customers to discuss casting design issues upfront for the betterment of both the customer and foundry.

According to Burkhardt, the old financial model (a customer's casting cost equals the casting production cost plus the profit margin) is outdated. Today's casting cost is a total cost, which equals the sum of component production costs (including casting and value-added processes such as heat treating and machining costs) and the profit margin. Foundries must design value into their castings by trying to eliminate or reduce "down-the-road" processes such as machining. "Remove the value-added waste and your customer will thank you," he said.

By casting in features to a component that previously had to be machined, a foundry can increase its total component cost because it has reduced the machining cost. However, the foundry also must communicate to its customers the idea of total cost so they can understand the added value of the component. If customers do not understand the value added to the component, it will be judged solely on casting price and lose out to less value-added components, he said.

Burkhardt believes this process begins with visits to existing customers to gain a good understanding of how castings are machined, inspected and assembled in the final product. From there, foundries must determine ways to redesign the cast component to incorporate new design features. For example, the parting line may be changed to eliminate a trim press operation, or the draft may be altered to eliminate some of the machining stock.

Burkhardt stressed the importance of foundries using technology such as CAD, CAM, FEA and simulation software in this upfront design work, "because this is the technology language design engineers understand." However, said Burkhardt, the old adage of if at first you don't succeed, try, try again definitely applies as customers may not accept your first redesign attempt, but once they do "you will have a customer for life."

Dealing with Shrinkage

Eli David, Globe Metallurgical Sales, Inc., Cleveland, outlined the various conditions and techniques that can influence shrink tendency in ductile iron.

According to David, the main influences on the "complex nature of shrinkage," include:

* melt composition, nucleation and oxidation;

* pouring temperature;

* sand composition, compaction and hardness;

* molding medium;

* casting shape;

* ferrostatic pressure;

* gating and risering;

* magnesium (Mg) treatment process;

* inoculation methodology.

One of the best weapon's against shrink are inoculants, which David said benefited ductile iron by allowing for lower Mg residual, deoxidization, a lower liquidus, a raised eutectic and an increased nodule count. He singled out rare earth-based and bismuth-plus-rare earth inoculants as recent developments showing promise.

Practical metallurgical tips to remedy shrinkage include: avoid superheating, minimize melt oxidizing conditions, keep carbon as high as possible, keep silicon on the lower end, pour as cold as possible, keep Mg as low as possible, optimize total rare earth additions and ensure the stream inoculant is sufficient.