Kennametal 4109638 Threading Insert NAS3L8 KCU25 Carbide

Product Description

The KENNAMETAL 4109638 is a carbide threading insert designed for cutting Stub Acme threads at 8 threads per inch (TPI). Part of the Top Notch series, it carries a KCU25 manufacturer grade and an aluminum titanium nitride (AlTiN) finish applied via physical vapor deposition (PVD). The insert handles both internal and external thread forms and is ground for left-hand cutting direction. With a 29-degree included angle and a cutting tip width of 0.0476 inches, it suits precision threading operations on lathes and turning centers where consistent thread form and tool life are priorities.

This insert is suited for threading applications in metalworking environments, including job shops, production machining, and maintenance repair operations. The Stub Acme thread standard is common in linear motion components, power screws, and feed mechanisms where a full Acme form is impractical due to space or load constraints. The left-hand orientation serves applications requiring reverse-thread workpieces. Licensed machinists and CNC operators are the primary installers of this insert type.

Key Features

• KCU25 carbide grade with AlTiN PVD finish for wear resistance and heat tolerance
• Stub Acme thread form at 8 TPI with a 29-degree included angle
• Left-hand insert hand for reverse-thread and left-hand helix applications
• Cutting tip width of 0.0476 inches for controlled thread root geometry
• Compatible with both internal and external thread cutting operations
• Top Notch series insert style for use with compatible Top Notch toolholders

Compatibility

Designed for use with Kennametal Top Notch series toolholders that accept NAS-style inserts in size 3. Confirm toolholder insert pocket geometry and hand orientation before installation.

Installation Notes

Installation is performed by qualified machinists on CNC or manual lathes. Power down and lock out the machine spindle before seating or removing the insert. Use the appropriate torx or clamp screw driver specified for the toolholder to secure the insert without overtightening the clamping mechanism. Inspect the insert seat and clamping components for chips or debris before mounting.