The Walter Prototyp Paradur short chip HT blind hole tap is designed to increase process reliability and quality when tapping long-chipping high tensile (HT) strength steels.
The design of the tap has a 15-degree helix angle for easy chip removal even in deep (3.5 × D) and protected threads, the company says. This reduces to a 9-degree helix angle which, combined with a ground rake in the chamfer, ensures the creation of short chips. Axial internal cooling rinses these chips out of the hole through the spiral flutes.
The cutting edges have an adjusted rake angle. Tool life is enhanced by a THL hard coating, except on the reduced helix in the lower section of the tool, which is ground after the coating is applied. The bare surface of the rake at this point aids chip breaking.
This combination of features enables the Prototyp Paradur Short Chip HT to reduce machine downtime, reduce tooling costs due to longer tool life, and produce clean and chip-free threads, according to the company. Interference contour is no problem because of the short chips. While the short chip HT delivers these benefits on high-tensile, long chipping materials, it can also be used on low-tensile strength materials such as aluminum alloys or ductile cast iron.
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