Walter-prototyp 7427639 Thread Forming Tap 1/4-20 Unc Tin

Product Description

The WALTER-PROTOTYP 7427639 is a right-hand thread forming tap in the TC410 Advance series, designed to cut 1/4-20 UNC internal threads without producing chips. It is manufactured from High-Speed Steel-E (WY80AD grade) and coated with Titanium Nitride (TiN) for extended tool life and reduced friction. With an overall length of 3.1496 inches (80.00 mm) and a thread length of 0.5906 inches (15.00 mm), this tap suits blind-hole and through-hole threading operations. Licensed HVAC, plumbing, maintenance, and metalworking trades rely on this tool for precise thread forming in a range of metals. Class of fit is 2BX with a modified bottoming chamfer of 2 to 3 threads.

This tap is built for productive threading in steel, stainless steel, cast iron, non-ferrous metals, and superalloys, corresponding to material application codes P, M, K, N, and S. The modified bottoming (semi-bottoming) chamfer makes it effective in blind holes where thread engagement close to the bottom is required. The 3.5xD flute-by-diameter ratio and five oil grooves support efficient forming without coolant-through capability. It is well suited for production machining environments and precision maintenance applications where thread quality and consistency are critical.

Key Features

• Thread size 1/4-20 UNC, Class of Fit 2BX, right-hand thread direction
• Modified bottoming chamfer with 2 to 3 chamfered threads for blind-hole capability
• High-Speed Steel-E construction with Titanium Nitride coating for wear resistance
• Five oil grooves and 3.5xD flute-by-diameter ratio for controlled forming action
• Tapping depth of 1.1811 inches (30.00 mm); shank diameter 0.2756 inches (7.00 mm)
• Suitable for blind-hole and through-hole threading in steel, stainless, cast iron, non-ferrous, and superalloy materials

Compatibility

Designed for use in steel, stainless steel, cast iron, non-ferrous metal, and superalloy workpieces requiring 1/4-20 UNC internal threads; compatible with standard tap holders and chucks accepting a 0.2756-inch shank and 0.2165-inch square drive (5.50 mm square).

Installation Notes

Thread forming taps should be installed by machinists or qualified maintenance technicians using a tap holder matched to the shank and square dimensions. Ensure the machine spindle is fully stopped and locked out before changing tooling. Apply appropriate tapping fluid or cutting oil to the tap and workpiece prior to use, as coolant-through is not available on this tool. Follow the workpiece manufacturer and shop safety procedures for speeds and feeds when threading the specified material type.