Dormer Pramet

Drill geometry allows for continuous support

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Traditionally, web thinning is performed as an additional operation after point grinding. A drill point is thinned by shortening the length of the chisel edge to reduce the thrust force needed when drilling. 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," Ricky Payling, Dormer Pramet’s application specialist for rotary tools, explains. “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 for increased cutting speeds and greater performance reliability without compromising tool life.”


CTW reduces time needed for regrinding

CTW reduces time needed for regrinding

Regrinding a drill can be a cost-effective solution for an end-user to extend the life of a cutting tool, but it can be a complex procedure and needs to be performed accurately to ensure the product achieves a consistently good level of performance. “Generally, a drill after re-grind will be at around 75-80% of its original qualities and performance, but with CTW included, this increases significantly to 90-95%,” Payling says. “Also, a regrind company working with a batch of drills with CTW included will significantly reduce its lead time, compared with those that do not. This offers a quick turn-around for customers, simplified logistics, and machine downtime is kept to a minimum.”

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Installing CTW into a drill not only enables the complexities of the regrinding operation to be reduced but because an amount of the web thinning is built into the design, the symmetry of the tool is retained after regrind. This means the drill will not degenerate over time and will maintain its torque strength after repeated regrinds. By integrating part of the web-thinning feature within the flute form, the design is effectively thinned throughout the life of the drill, without passing on the costs and difficulties associated with this additional operation to the user. Also, as thrust forces are kept consistently low, the result is less wear and tear on the machine tool, providing another time and cost-saving benefit for the end-user.