OSG (Japan) is one of the world’s most respected tap manufacturers. Their series naming follows clear logic.
OSG Tap Series
- EX series (EX-SFT, EX-LT, EX-H) — Premium HSS-Co cutting taps. EX-H specifically for hardened steel up to 50 HRC.
- A-Tap series — Powder-metal HSS-PM, longer life than HSS-Co
- NRT (Nano-Roll Tap) — Forming taps with nano-coating for stainless
- VTH/VFL series — Carbide cutting taps for hardened materials above 50 HRC
- ADO drills (related family) — Through-coolant solid carbide drills
Selection by Material
| Material | OSG Recommendation |
|---|---|
| Mild steel through-hole | EX-SFT (spiral-point) |
| Mild steel blind-hole | EX-LT (spiral-flute) |
| Stainless 304/316 | NRT forming or EX-LT HSS-PM |
| Hardened steel 30-45 HRC | EX-H |
| Hardened steel 45-60 HRC | VTH carbide |
| Aluminum/copper | NRT forming (chip-free) |
| Cast iron | EX-Z straight-flute |
Why OSG Tops the List
OSG taps in production tapping of difficult materials (hardened steel, stainless above 35 HRC) routinely deliver 2-3× the hole count of generic HSS taps. Premium price (often 2-3× generic) pays back via reliability.
See our hardened steel tap guide.
