To All:
Here's an advertising blurb from "Production Machining" magazine that highlights some cut taps for specific materials from Dormer.
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Cut taps available include Silver Ring for steel, Black Ring for hardened/tough steel, Blue Ring for stainless steel and Green Ring for aluminum. The color rings on the shanks of these taps denote the primary material group the taps are designed for. When used in conjunction with the company's Application Material Group charts, the ring color coding makes it easy to choose the right tap for an application, the company says. All of the Shark taps are available in spiral flute and spiral point designs, in UNC, UNF and metric sizes.
The taps are designed to include high productivity, long tool life and excellent chip management and evacuation. Surface treatments and coatings include Super-B, TiAN, bright finish and a combination steam tempering/TiAN. ============================================================