The new drill offers metal-removal rate increases up to 100 percent over competitive gun and high-speed steel drills, and a minimum of 10 percent better metalremoval rates compared with competitive solidcarbide products when drilling at depths of 15 and 20 times diameter.
The drill point has a four-margin design to maintain stability throughout the cut. These margins are located only on the forward portion of the drill. The diameter behind the flutes is slightly smaller providing more chip clearance and less contact with the hole wall. Its 135-degree high-positive point geometry reduces thrust necessary to create a hole and provides centering ability to increase accuracy.
“The four-margin design helps keep the drill stable and on course even when it passes through a crosshole in the workpiece,” said Chuck Petrosky, a Kennametal staff engineer in the Holemaking Products Engineering department. “When you drill a hole that deep, the substrate needs to have high torsional strength so it doesn’t fracture.”
The Long-Length Drill’s 12.5 percent cobalt submicron substrate and hard physical vapor deposition coating provides durability, toughness, and wear resistance. The drill’s post-coat treatment (polishing) reduces friction in flutes, on margins and the cutting edge, and its 30-degree helix helps effectively convey chips from the hole
The Long-Length Drill has two cutting surfaces, compared with one on gun drills. And because it’s made of carbide, it can be pushed hard and fast. The company said productivity is at least doubled. The new drill is available in standard diameters ranging from 3 mm to 13 mm and in standard lengths including 15, 20, 25 and 30-times diameter. Custom drill diameters and lengths also can be provided.