Designed for precision threading in blind holes, the OSG UNC Spiral Flute Threading Tap No. 4 x 40 delivers clean, accurate threads with exceptional durability. Built for professional machinists and production environments, it combines HSS-E cobalt with a Steam Oxide coating to withstand heat and wear.

• Thread type: UNC spiral flute design enhances chip evacuation in blind holes, reducing breakage and improving start-up.
• Material: HSS‑E (high-speed steel with cobalt) for improved hardness and heat resistance, extending tool life.
• Coating: Steam oxide coating provides added wear and corrosion resistance in demanding materials.
• Size: No. 4 x 40 UNC tapping specification for small fasteners and compact assemblies.
• Application: Optimized for tapping blind holes where reliable chip clearance matters.
• Quality and precision: OSG's advanced threading technology ensures accurate thread form, tight tolerances, and consistent results.
• Usage: Suitable for manual tapping with a compatible tap handle or machine tapping in CNC/fixture setups.

With its spiral flute geometry and cobalt-enriched HSS core, this tap delivers smoother starts, cleaner threads, and extended tool life even in tougher metals. The steam oxide finish reduces galling and wear, helping maintain accuracy across long production runs. Ideal for small fasteners used in electronics, automotive assemblies, precision machinery, and hobbyist projects where dependable No. 4-40 threads are crucial. Choose OSG threading taps when you need consistent thread quality, fewer reworks, and a reliable tool that performs on day-in, day-out jobs.