The Oxford English Dictionary defines perfection as "the condition, state or quality of being perfect or free from defect; supreme excellence; flawlessness, faultlessness." While the definition seems like a tall order to fill, it can equate in the real world. Alcoa Mill Products, Lancaster, Pa., strives for this ideal with its MIC-6 cast aluminum plate, and it is succeeding in the minds of many design engineers who choose the product for their precision applications.

Although MIC-6 is hardly a new product, it hasn't yet found its rival. Since joining the facility five years ago, Ray Hughes, plate mill and product manager for Alcoa's Lancaster cast plate plant has been proud to be part of both the plant and its product, MIC-6, because of their reliable performance. Late shipments and product defects are almost unheard of with MIC-6. But these results have not happened by chance. The Alcoa Business System helps employees at the Lancaster mill make continual improvements to uphold the company's reputation for quality customer service.

MIC-6's flatness tolerance at 0.005 inch for plates 3/4 inch and over and 0.015 inch for plates between 1/4 inch and 5/8 inch has set the bar for the industry standards in comparable plate. With numbers like that, there's no doubt that perfection is in the minds of Alcoa's cast plate team.

"MIC-6 offers the best dimensional stability and tolerance control," Hughes says. "This difference comes from the casting process, which is the most advanced process used in the cast plate industry." No other product in the industry promises the control in flatness that Alcoa offers with MIC-6. Its ultra-low levels of stress and near-net thickness lend to the dependability of the cast plate product.

But flatness is only part of the equation. "Dimensional stability is really the proof in the pudding," Hughes says. "If your plate is used in an application that requires a significant amount of material removal and machining, will it still be flat at the end of the process' In these critical flatness applications, distortion is simply unacceptable. To avoid distortion, you need the best available dimensional stability." With statements such as "'good enough' is never good enough" and "the best of the best," Alcoa's product literature accurately describes Hughes' confidence in the product.

In the cast house
Fifty years ago, as applications required greater levels of dimensional stability, metal manufacturers began researching how to deliver what their customers were lacking. The porosity and uneven solidification of early cast plate products created significant issues that propelled the industry toward a solution. Several generations of improvements followed, which ultimately led to what today remains the premier cast plate product.

The advantages offered by the manufacturing process for MIC-6 begin with casting individual plates to near-net thickness. The technology used in the casting process allows even solidification throughout the plate, providing a uniform grain structure that supports the consistent performance in a variety of applications. By casting to near-net thickness, material removal is minimized, reducing the risk of disrupting material stability.

"The key to dimensional stability is to start with the best cast product," Hughes says. "The MIC-6 casting process results in virtually zero stress inside the plate, as opposed to other products where thick ingots solidify at different rates." But Alcoa doesn't stop there. After solidification, seemingly perfect plates are put through a stress-relief process where they are subjected to Alcoa's thermal treatment. Then, each plate is surface machined to its final gauge, providing precise tolerances and a smooth surface finish.

A variety of uses
When Alcoa ships out MIC-6 plates, it often doesn't know the environment that they will land in or their end-use application. But Alcoa doesn't have to. Regardless of the destination, MIC-6 has consistently performed, even in unstable settings that are prone to cause distortion in other cast plate products. And to ensure its stability, each plate is individually inspected to verify the metal's flatness and thickness.

"We know that in some cases our plate is used in the most challenging applications," says Hughes. "That makes the impeccable performance even more impressive. End users have told us that [our product is] seeing the most demanding applications because some of the other products just won't handle them."

MIC-6 isn't always used in uncommon situations, however. It often finds itself in fixtures, base plates, side panels and indexing tables. Typical applications include but certainly are not limited to checking fixtures, food-processing, packaging and printing equipment, and semi-conductor holding trays.

It finds its way into a variety of industries that require extreme flatness, such as aerospace and quality control. Other industries utilize processes at elevated temperatures that can distort other products. Still others may require significant metal removal in the manufacturing of the part, resulting in the release of trapped stresses in other plates. While these industries have different challenges, the use of MIC-6 can alleviate end users' stress and most importantly, the stress found within their material.

Whatever the application, it all goes back to the dimensional stability. One of the key advantages of MIC-6 is its casting to near-net thickness; however, that doesn't mean that a customer can't perform extensive machining on a part. "Extreme metal removal is challenging enough. If you have any stresses inside that plate, they will show up," Hughes says. "And that's where satisfied customers have said, 'I use MIC-6 because it has withstood this, and I haven't been able to find anything else that works.'"

For applications that require critical tolerance control, machining costs often significantly exceed material costs. After intricate machining or extensive metal removal, end users can't be forced back to square one because the material used failed to remain flat. MIC-6 provides the best solution in both performance and total application cost.

The list of satisfied customers is constantly growing, and Hughes believes that there are more opportunities for MIC-6 to solve fixture and component challenges. After using MIC-6, machine shops and end-users have said that they prefer MIC-6 over other cast plate products because of its consistent performance, machinability, superior flatness and dimensional stability. "We have a proven track record of performance that you can trust. We understand our core capabilities, and we want to provide solutions for applications that need those capabilities," says Hughes.

In a world where perfection is a subjective concept, it is safe to say that Alcoa's customers have found a product as free from defect and flaws as possible. When design considerations permit a cast metallurgical structure, the solutions it offers are unmatched, leaving MIC-6 as the perfect choice for critical applications. MM

By Abbe Miller, from the May 2006 issue of Modern Metals.