Kennametal 4109644 Threading Insert NAS3R8 KCU25 Carbide

Product Description

The KENNAMETAL 4109644 is a carbide threading insert designed for cutting Stub Acme threads at 8 threads per inch (TPI). It carries the KCU25 manufacturer grade and features a Physical Vapor Deposition (PVD)-applied Aluminum Titanium Nitride (AlTiN) finish coating for improved wear resistance and heat management at the cutting edge. Part of the Top Notch series, this insert is sized at Insert Size 3 and has a cutting tip width of 0.0476 inches (1.21 mm), a corner radius of 0.005 inches (0.13 mm), and a 29-degree included angle. It is configured for right-hand cutting and handles both internal and external thread applications. Machinists and toolroom professionals install this insert into compatible Top Notch toolholders on CNC lathes and manual turning equipment.

This insert is suited for threading operations on Stub Acme profiles in metalworking environments where tight thread geometry and surface finish are required. The Stub Acme thread form is common in power transmission components, lead screws, and linear motion hardware found in both production and maintenance machining. The AlTiN PVD coating supports cutting in alloy steels and harder workpiece materials. The right-hand orientation applies to the majority of conventional turning setups. Both internal and external thread cutting are supported, making this a versatile insert for shops running varied threading jobs on a single toolholder platform.

Key Features

• KCU25 carbide grade with PVD-applied AlTiN coating for wear resistance in demanding threading operations
• Stub Acme thread standard at 8 TPI with a 29-degree included angle
• Right-hand insert configured for both internal and external thread cutting
• Cutting tip width of 0.0476 inches (1.21 mm) with a 0.005-inch corner radius for accurate thread form
• Part of the Top Notch series for use with compatible Top Notch toolholders
• Insert Size 3 with a thickness of 0.1949 inches (4.95 mm)

Compatibility

Designed for use in KENNAMETAL Top Notch series toolholders that accept NAS-style Insert Size 3 threading inserts. Verify toolholder designation against KENNAMETAL Top Notch system specifications before ordering.

Installation Notes

Threading inserts should be seated and indexed by a qualified machinist or toolroom technician. Power down and lock out the machine spindle before changing or indexing inserts. Use the correct torque wrench and Top Notch clamping hardware as specified by the toolholder manufacturer — do not overtighten the clamping screw by feel alone. Inspect the insert pocket for chips or debris before seating the new insert to ensure proper contact and thread-form accuracy.