Dormer Pramet's continuously thinned web (CTW) technology is unique to the company's rotary drilling range. Traditionally, web thinning is performed as an additional operation after point grinding, according to the company. A drill point is thinned by shortening the length of the chisel edge to reduce the needed thrust force. CTW technology simplifies the chisel thinning process as the depth is already set, and, therefore, no adjustments are needed during regrind, regardless of drill length.

"CTW increases both flute volume and cross sectional strength," said Ricky Payling, application specialist at Dormer Pramet. "The combination of these elements ensures consistent forces throughout the drilling cycle, with little or no increase in power requirement as the drill penetrates deeper into the hole. This, in turn, allows increased cutting speeds and greater performance reliability without compromising tool life."

Dormer Pramet's R459 solid-carbide drill is for producing holes up to 8 diameters deep. Image courtesy Dormer Pramet.

The point design of the R459 drill after machining stainless steel for 30 minutes. Image courtesy Dormer Pramet.

Payling noted tool symmetry is retained after regrinding because an amount of web thinning is built into the design. This means the drill will not degenerate over time and will maintain its torque strength.

Dormer Pramet provides CTW in its new R459 drill for producing holes up to 8 diameters deep. However, the toolmaker hopes to expand its use to other drills in the near future.

In-house tests show how well the R459 drill cuts aluminum, hardened steel and stainless steel. For example, after drilling 316-L stainless steel at a cutting speed of 35 m/min. (114.8 sfm), a spindle speed of 1,395 rpm and a feed rate of 0.1 mm/rev. (0.004 ipr), or 140 mm/min. (5.51 ipm), for 30 minutes, the cutting edges showed a small amount of pick up with an even wear scar running across them.

After machining aluminum for 30 minutes at a cutting speed of 285 m/min. (935 sfm), a spindle speed of 11,340 rpm and a feed of 0.26 mm/rev. (0.010 ipr), or 2,950 mm/min. (116.1 ipm), the R459 drill showed minimal edge wear, with a small amount of pick up.

For more information about Dormer Pramet, Elgin, Ill., call (847) 783-5700, email cs@dormer pramet.com or visit www.dormer pramet.com. CTE

About the Author: Matt Jaster is senior editor of CTE. Contact him at (847) 714-0174 or [email protected].