The Walter Prototyp Paradure short-chip blind-hole tap from Walter USA is designed to increase process reliability and quality when tapping long-chipping, high-tensile-strength steels. The tap is said to eliminate bird’s nest swarf while increasing machine uptime and tool life. The 15-degree helix angle enables easy chip removal even in protected threads and depths ranging to 3.5×D. The helix angle is reduced to 9 degrees and combines with a ground rake in the chamfer to ensure the creation of short chips, the company says. Axial internal cooling rinses these chips out of the hole through the spiral flutes.
Cutting edges feature an adjusted rake angle, and the THL hard coating extends tool life. The reduced helix in the lower section of the tool is ground after the coating is applied, but the bare surface of the rake at this point aids chip breaking, the company says. The tap is designed for high-tensile, long-chipping materials, but can also be used on low-tensile-strength materials such as aluminum alloys or ductile cast iron.