Balax 10852-81L Thread Forming Tap 4-40 Unc Bottoming

Product Description

The BALAX 10852-81L is a thread forming tap designed for blind hole threading in die cast aluminum. Unlike cutting taps, thread forming taps cold-form threads by displacing material rather than removing chips, producing stronger threads with no swarf to clear. This tap is manufactured from powdered metal high-speed steel and carries a Bal-Plus coating for improved wear resistance and lubricity. It is configured in a bottoming chamfer style with 2.5 chamfered threads, allowing thread formation close to the bottom of a blind hole. The 2B class of fit and H5 thread limit make it suitable for standard fastener engagement in precision assemblies. Machinists and toolroom technicians working with die cast aluminum components are the primary users.

This tap is intended for use in die cast aluminum applications where blind hole threading is required. The BXDIECAST series designation indicates it is optimized for the material properties and thin-wall characteristics common in die cast parts. The bottoming chamfer allows threading to near-full depth in shallow blind holes, a common requirement in aluminum housings, brackets, and enclosures found in HVAC, electrical, and industrial equipment manufacturing. It threads right-hand 4-40 UNC at a 2B class of fit with an H5 thread limit.

Key Features

• Thread forming design displaces material rather than cutting, producing stronger threads and eliminating chip removal in blind holes
• Powdered metal high-speed steel construction provides uniform grain structure and extended tool life compared to standard HSS
• Bal-Plus coating improves surface lubricity and wear resistance for consistent thread quality across production runs
• Bottoming chamfer with 2.5 chamfered threads allows threading close to the bottom of blind holes
• Optimized for die cast aluminum via the BXDIECAST series geometry
• Two oil grooves support lubrication flow during forming

Compatibility

Designed for blind hole thread forming in die cast aluminum workpieces requiring 4-40 UNC threads at a 2B class of fit. Suited for applications within the BXDIECAST series material and geometry specifications.

Installation Notes

Thread forming taps require a properly sized forming tap drill hole, which is larger than a standard cut tap drill - consult a thread forming drill chart for the correct pilot hole diameter for 4-40 UNC in aluminum. Use a suitable tapping fluid or cutting oil formulated for aluminum to reduce forming load and extend tap life. Power down and secure the workpiece before tapping operations. Thread forming taps should never be used in brittle materials such as cast iron, as the material must be ductile enough to cold-form.