Injection molds: Conformal cooling lines improve with aerospace bonding tech

Refrac Systems (Chandler, AZ), which was established in 1984 as a specialist in vacuum metallurgy and diffusion bonding, has formed a subsidiary, Die-Bond LLC, to provide Liquid Interface Diffusion (LID) bonding services on customer-supplied mold inserts and mold plates for custom plastic injection molds requiring conformal cooling channels.

Several years ago, Refrac began working with some mold manufacturers to develop a more efficient process to bond mold inserts together. With the formation of Die-Bond, mold manufacturers who incorporate conformal cooling channels into molds have access to Die-Bond's proprietary technology, which it says minimizes the potential for leakage and post-braze warpage, which Die-Bond calls the number once concerns when conformal cooling molds are assembled using conventional vacuum brazing.

"With Die-Bond's LID bond process to bond in conformal cooling lines, mold makers can easily get the cooling exactly where they need it to improve molding cycle times," comments Refrac Systems founder and president Norman D. Hubele. He notes that, by largely eliminating leakage and warpage problems, LID bonding allows the mold designer greater freedom in creating the complex conformal cooling channels that put the cooling exactly where it's needed. Because the mold plates are bonded using a special-built vacuum hot press that applies the tonnage needed to bring the parent metal atoms together during the joining operation, the ultra-thin (0.001-inch thick) metal sheet used in the LID bonding process actually becomes one with the parent metal.

"The Die-Bond LID bonding process means there is no cracking of the mold during post machining or heat-treating of the mold because the metal's atoms actually commingle and fuse, resulting in a much more ductile post bond structure," Hubele states. Die-Bond's LID bonding process also allows small mold inserts to be hardened under extensive tonnage, reducing the risk of warping during the "quenching" operation of traditional vacuum brazing.

The company says the results include more consistent yields and reduced costs for injection mold manufacturers. LID bonding also eliminates the need for water line plugs for drilled holes, which means no potential for plug leaks or corrosion.

Die-Bond will be moving into a separate, new facility in early 2011 that will house a new bonding furnace, an investment of nearly $2 million, to accommodate the growing conformal cooling business. Both Die-Bond LLC and Refrac Systems Inc. are AS9000 and ITAR compliant. 

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