Osg 1012205 Straight Flute Tap 4-40 Unc Hss Tin

Product Description

The OSG 1012205 is a straight flute tap designed to cut 4-40 UNC internal threads in a range of ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, this tap delivers improved wear resistance and reduced friction compared to uncoated HSS tooling. It features a plug chamfer, which distributes cutting load across the first several threads for smooth thread entry. With a 3-flute design and right-hand thread direction, the 1012205 suits production and maintenance threading operations. Overall length is 1-7/8 inches with a thread length of 9/16 inches. Machinists, tool-and-die technicians, and maintenance mechanics install this tap in manual or CNC tapping setups.

The 1012205 is suited for threading operations in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. The 4-40 UNC thread size is common in small fastener applications across electronics assembly, instrumentation, and light mechanical fabrication. The plug chamfer style makes this tap appropriate for through-hole threading where moderate lead-in is acceptable. It carries a 2B class of fit, the standard tolerance class for general-purpose inch-series internal threads, and an H2 thread limit for consistent dimensional control.

Key Features

• 4-40 UNC thread form at 40 threads per inch with right-hand thread direction
• Plug chamfer distributes cutting load for smooth, controlled thread entry
• TiN coating improves surface hardness and reduces built-up edge in ferrous and aluminum materials
• HSS construction provides toughness for hand tapping and low-speed machine tapping
• H2 thread limit and 2B class of fit for general-purpose dimensional accuracy
• 3-flute geometry supports chip clearance in through-hole applications

Compatibility

Designed for use in through-hole tapping applications requiring 4-40 UNC internal threads at a 2B class of fit. Compatible materials include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel as specified by the manufacturer.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap wrench, tapping head, or CNC rigid tapping cycle. Before use, ensure the workpiece is secured and the pilot hole diameter matches the recommended tap drill size for 4-40 UNC. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Reverse the tap periodically when hand tapping in harder materials to break chips and reduce the risk of tap breakage.