Kennametal 1540415 Hand Tap 4-40 Unc Plug Rh Hss

Product Description

The KENNAMETAL 1540415 is a straight-flute hand tap designed for cutting 4-40 UNC internal threads by hand or with a tapping fixture. Manufactured from high-speed steel with a bright uncoated finish, it produces right-hand threads to a class 2B and 3B fit at an H2 thread limit. The plug chamfer provides a gradual lead-in that suits through-holes and blind holes with sufficient depth. Overall length is 1.88 inches, with a thread length of 0.563 inches and a shank diameter of 0.141 inches. It carries two straight flutes and does not require coolant-through capability. This tap belongs to the KENNAMETAL Series 5305 and 5303 product lines.

This tap is suited for threading small-diameter fastener holes in cast iron and non-ferrous metals such as aluminum, brass, and copper. Typical applications include instrument housings, electrical enclosures, light-duty mechanical assemblies, and prototype fabrication where 4-40 machine screws are the specified fastener. The straight-flute geometry works best in shorter-chipping materials and shallow-to-moderate blind holes where chip clearance is not the primary concern.

Key Features

• 4-40 UNC thread form, right-hand cut, classes 2B and 3B
• H2 thread limit for close tolerance fit control
• High-speed steel construction for durability across cast iron and non-ferrous applications
• Bright uncoated finish - suitable for use with cutting oil or standard tapping fluid
• Plug chamfer (3-5 thread lead) allows use in through-holes and sufficiently deep blind holes
• 2-flute straight-flute design for use in shorter-chipping materials

Compatibility

Designed for cutting 4-40 UNC internal threads in cast iron and non-ferrous metals. Compatible with standard tap wrenches and tapping fixtures that accept a 0.141-inch shank diameter.

Installation Notes

Installation should be performed by a machinist or skilled tradesperson using an appropriately sized tap wrench or tapping fixture. Secure the workpiece firmly before tapping and apply a suitable cutting fluid for the base material to reduce heat and extend tool life. Back the tap off periodically to break chips and clear the flutes. Do not force the tap if resistance increases unexpectedly, as breakage in small-diameter taps is difficult to recover from.