Osg 1400105901 Thread Forming Tap 4-40 Unc Plug Cobalt

Product Description

The OSG 1400105901 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without cutting or producing chips. Built from cobalt high-speed steel with a steam oxide coating, it handles demanding materials and elevated heat without premature wear. The plug chamfer style with 4 to 4.5 chamfered threads provides a smooth thread-forming entry, making it suited for through-hole threading applications. At 1.875 inches overall length with a 0.141-inch shank diameter, this tap fits standard tap holders used in production and job-shop environments. It produces a 4-40 UNC thread at an H3 thread limit with a Class 3B fit. Licensed machinists and toolroom technicians are the primary installers.

This tap is built for through-hole threading in a wide range of workpiece materials. Its cobalt construction and steam oxide finish make it appropriate for alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The 4-40 UNC thread form is common in precision assemblies, electronics hardware, and light mechanical components where fine, strong threads are required in small-diameter holes. Typical use is in CNC tapping centers, drill presses with tapping attachments, or hand-tapping operations requiring consistent thread quality.

Key Features

• Cobalt high-speed steel construction resists heat and wear in tough ferrous and non-ferrous materials
• Steam oxide coating reduces friction and improves lubrication retention during the forming process
• Plug chamfer with 4 to 4.5 chamfered threads for smooth entry in through-hole applications
• H3 thread limit with Class 3B fit for precise, consistent thread geometry
• Right-hand thread direction, 40 threads per inch, 4-40 UNC standard
• No coolant-through requirement simplifies setup in standard tapping operations

Compatibility

Designed for through-hole threading in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Compatible with standard tap holders sized for a 0.141-inch shank diameter.

Installation Notes

Thread forming taps require proper lubrication and correct spindle speed for the workpiece material — consult published speeds and feeds for cobalt taps in the target material before operation. The workpiece hole must be drilled to the correct forming tap drill size for a 4-40 UNC thread, which differs from the drill size used for a cutting tap. Secure the tap in a floating or rigid holder appropriate for the machine type. Inspect the tap and holder for runout before production use to avoid thread form errors or tap breakage.