Walter-prototyp 7427634 Thread Forming Tap 4-40 Unc

Product Description

The WALTER-PROTOTYP 7427634 is a thread forming tap designed for cold-form threading in blind and through-hole applications. Part of the TC410 Advance series, it cuts no chips - instead displacing material to produce a stronger, cleaner thread. The tap is manufactured from High-Speed Steel-E (HSS-E) with a Titanium Nitride (TiN) coating to extend tool life and reduce friction during tapping. It produces 4-40 UNC threads to a 2BX class of fit with a modified bottoming chamfer, making it well suited for tight-tolerance fastener holes in precision assemblies. Licensed machinists and toolmakers are the primary users of this tap.

This tap is intended for use in steel, stainless steel, cast iron, non-ferrous metals, and superalloys. It is optimized for blind-hole and through-hole threading in small-diameter applications where thread strength is critical. The modified bottoming chamfer with 2-3 chamfered threads allows threading closer to the bottom of a blind hole than a standard plug tap. It is commonly used in aerospace, medical device, and general precision machining environments where 4-40 UNC fastener holes are required.

Key Features

• Thread forming (chipless) design produces stronger threads by cold-working the material rather than cutting
• TiN coating reduces friction and extends tool life across a broad range of workpiece materials
• Modified bottoming chamfer (2-3P) allows threading close to the bottom of blind holes
• HSS-E substrate provides toughness and heat resistance for demanding tapping operations
• 3 oil grooves support lubrication delivery during tapping for improved surface finish and tool longevity
• Right-hand thread direction, 4-40 UNC, 2BX class of fit for standard inch fastener compatibility

Compatibility

The 7427634 is designed for 4-40 UNC thread forming in steel, stainless steel, cast iron, non-ferrous metals, and superalloys, covering material application codes P, M, K, N, and S. It is part of the Walter TC410 Advance series and is intended for use in both blind-hole and through-hole threading operations.

Installation Notes

This tap should be installed in a rigid tapping holder or tension-compression tap holder to accommodate the forming torque associated with chipless thread forming. Always apply a suitable tapping fluid or cutting oil rated for the workpiece material before and during the tapping operation. Power down and secure the machine spindle before changing or inspecting taps. Thread forming taps require a specific tap drill size that produces a larger pilot hole than cutting taps - consult the appropriate thread forming tap drill chart for 4-40 UNC before drilling.