Crystal persuasion: General Industry Coverage

A random arrangement is all well and good when it comes to avant-garde music, but the random crystal growth direction found in conventional CVD alumina cutting tool coatings can create weak areas where cracks form, shortening tool life. According to Sandvik Coromant Co., the new Inveio CVD alumina coating on its GC4325-grade inserts has a unidirectional crystal orientation—where every crystal is aligned in the same direction—that resolves that issue.

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“The crystal structure is oriented where the strongest direction of the crystal is pointing toward the cutting edge,” said John Winter, product and application specialist for the toolmaker. “With that tightly packed crystal structure, you eliminate weak spots within the coating, which allows the performance of the cutting edge to be more consistent.”

He added that the coating structure also helps disperse heat along the crystal planes and away from the cutting zone. Based on the company’s tests, the new coating increases tool life 20 to 30 percent. In addition, because end users have a high level of tool life predictability with the inserts, they are appropriate for unattended machining.

Courtesy of Sandvik Coromant