Kennametal 4059939 Milling Insert LNEU1240R16 4 KC725M

Product Description

The KENNAMETAL 4059939 is a solid carbide milling insert carrying the ANSI and ISO designation LNEU1240R16 4 in manufacturer grade KC725M. This single-sided, rectangular insert measures 0.5000 inches in length, 0.3750 inches wide, and 0.1575 inches thick, with a 0.0630-inch corner radius and a neutral hand orientation. The PVD-applied TiAlN coating provides thermal and wear resistance suited to demanding milling operations. With four cutting edges and a honed cutting edge style, the insert delivers consistent performance in high-productivity facing, shoulder, and profile milling applications. A licensed machinist or CNC tooling technician is the typical installer.

This insert is designed for milling steel, stainless steel, superalloys, and titanium, corresponding to material grade codes P, M, and S. The positive rake geometry and common chip breaker configuration support efficient chip evacuation and reduced cutting forces across a range of feed rates and depths of cut. The LNEU series designation and LN cutter series compatibility make this insert a direct match for toolholders and milling bodies engineered to the LNEU insert platform. It is applicable in both light finishing and moderate roughing passes depending on machine rigidity and workpiece condition.

Key Features

• PVD TiAlN coating for high wear resistance and thermal stability in steel and superalloy milling
• Four cutting edges per insert maximizes economy per insert consumed
• Positive rake geometry reduces cutting forces and supports stable chip formation
• Honed cutting edge style minimizes micro-chipping on entry and exit
• Neutral hand design fits both left- and right-hand toolholder configurations in the LN cutter series
• Screw-held mounting method provides secure clamping and repeatable edge indexing

Compatibility

Compatible with LN cutter series milling bodies designed to accept LNEU-style inserts. ANSI and ISO standard designation LNEU1240R16 4 applies. Inscribed circle is 0.3750 inches; hole diameter is 0.1732 inches. Consult the toolholder manufacturer specifications to confirm pocket geometry and screw torque requirements before installation.

Installation Notes

Insert indexing and replacement should be performed by a qualified machinist or CNC tooling technician with the machine spindle fully stopped and the machine locked out per applicable safety procedures. Use the correct torque screwdriver specified by the cutter body manufacturer to seat the clamping screw — do not overtighten, as this can fracture the carbide insert. Inspect the insert pocket and seating surface for chips or burrs before installing a new edge. Verify correct insert orientation and hand designation before resuming the cut.