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Smith MegaDiamond Inc. and Star Cutter Company compared the performance of various end mills in carbon fiber reinforced plastic (CFRP). The tools tested included a coated carbide end mill, a diamond-coated end mill, a conventional PCD end mill with straight flutes, and a “veined” PCD end mll featuring a vein of PCD within a helical slot in a carbide tool body.

The table below summarizes the test parameters. Shown here is the video of a 30-degree helical veined PCD tool. Jeff Michael, engineering manager for Star Cutter, comments, “The sound is great. The corners are sharp, and the uncut fibers are minimal because of the shearing effect the geometry has. The last full cut was just to prove out the robustness of the tool, and would not be recommended in production. If you look closely, you can actually see the cutter glow. This does not damage the cutter. Other end mills broke when we attempted to run them at these parameters.”

 

 

	Tool Type
Ø .500 in.	Solid Carbide	CVD Diamond	PCD	Veined PCD
Flute angle	30° helical	10° helical	7° skew	30° helical
Spindle speed (rpm)	3,000	4,600	12,000	18,000
Chip load (in./tooth)	0.0035	0.0035	0.001	0.0065
Machine advance (in./min.)	42	64	36	470
Radial depth (in.)	.050	.050	.050	.050

Cutting speeds and feed rates were recommended parameters from each tool’s manufacturer.