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Recyclable Sealant Addresses Porosity in Castings

July 11, 2011
Conventional sealing technologies face increasing concerns about their efficiency and effluent impact.
Rexeal 100 (the white-blue substance on the casting above) is a new recyclable sealant that is up to 95% recyclable using Ultraseal Internatiol’s Sealant Recovery System (SRS).

Ultraseal America has developed a recyclable sealing technology that has improved environmental credentials and reliably solves the eternal problem of porosity in metal castings.

Ann Arbor-based Ultraseal is a distributor for Ultraseal International, which has focused on the problem of porosity in castings for more than 30 years. The company specializes in vacuum impregnation technology and associated processes. Through ongoing research and development of high-quality sealants, it has developed recycling sealants for the impregnation process.

Conventional sealing technologies face increasing concerns about their efficiency and effluent impact. In a traditional impregnation process, up to 90% of the sealant consumed goes down the drain as effluent from the cold water wash tank, a wasteful and cost-consuming byproduct, especially in the face of environmental regulations.

In 1987, Ultraseal introduced its first recyclable sealant, offering more technical benefits that conventional sealants as well as the commercial and environmental advantages of being recyclable. Instead of being washed down the drain, the sealant is collected from the wash tank and passed through the Ultraseal Sealant Recovery System (SRS) for retrieval and reuse. Not only is there a reduction in sealant consumption, but in water usage, too. This first generation of recycling sealant, Ultraseal MX2, has been in use for over two decades throughout the world.

Now, Ultraseal has introduced — Rexeal 100. This new recyclable sealant can operate in temperatures ranging from -105° to +428°F, suitable for parts such as engine and transmission casting that undergo thermal cycling.

Suited to modern lean manufacturing practices, parts can be impregnated in small batches as required. Ultraseal’s range of front-loading impregnation equipment also can be incorporated into an automated production line for those operations that impregnate all parts as a quality enhancement rather than on a selective basis.

When considering impact on the environment, Rexeal 100 has considerable advantages. Like Ultraseal MX2, it is far less wasteful of both chemicals and water than conventional sealant processes, in which 95% of the sealant is washed away each time, along with lots of water. Instead of being flushed away after the impregnation process, Rexeal 100 can be separated from the wash water in the SRS, which will return both the recycled sealant and the cleaned wash water in a closed-loop system for reuse in further impregnation cycles.

The Rexeal 100 formula is designed to enhance the performance of the sealant, taking into account extensive feedback from the market about customers’ evolving requirements, including higher thermal resistance. Accordingly, Rexeal 100 operates at temperatures up to 428°F, compared to a typical, commercially available methacrylate sealant that operates in ranges up to 356°F.

Rexeal 100 also has greater hydrophobic qualities, ensuring the sealant rejects moisture more quickly, and it is easier to wash excess sealant away after impregnation, leading to cleaner finished components. Process stability is improved, resulting in more easily maintained systems.

The sealant has been tested to stringent standards, including the Japanese heat/freeze cycle. It has also been extensively tested and carries the independent U.S. Military Specification MILI- 17563C (approval in Class 1 and 3). It also features the ability to withstand thermal cycling, as was demonstrated during an extensive tests of aluminum Mil Test rings that had been impregnated with Rexeal 100 and subjected to cycles of heat from -105° to +320°F at hourly intervals. At the end of the test, they were subjected to pressures of 290 PSI (20 bar) and remained sealed. Rexeal 100 is versatile and can be used on a wide variety of metal parts, from raw castings at a foundry to finished, machined and ready-to-assemble components.

Many customers with independently made systems have benefitted by converting to MX2 and Rexeal thanks to the upgrade and interface of Ultraseal’s SRS. This change has resulted in cost, quality and environmental benefits for manufacturers that already have invested in more basic batch type impregnation systems.