Stainless Steel Tapping Solution / Prevent Tap Breakage

When tapping high-hardness workpieces, tap breakage is a common problem. Taking 304 stainless steel as a typical example:
Stainless steel features poor thermal conductivity, high toughness, and strong material adhesion. The special metal elements inside stainless steel tend to bond with cutting tools, causing severe built-up edge, sticking and tool jamming during tapping.

 

Select cobalt high-speed steel (HSS-E) or powder metallurgy HSS taps for high heat resistance and mechanical strength.Coated taps are highly recommended.Coating TiCN or AlTiN.Stainless steel special taps are designed with a larger spiral angle or straight flute structure to ensure smooth chip removal.

Do not use forming taps for 304 stainless steel, which will easily cause chip clogging and tap fracture.

 

Due to high cutting resistance and work-hardening characteristics of stainless steel,keep the spindle speed at 50%–70% of the speed for ordinary carbon steel.Low speed effectively controls cutting heat and avoids work hardening.

 

Ordinary machine oil is not suitable for stainless steel.Adopt sulfurized chlorinated cutting oil, high-viscosity fluid or extreme pressure cutting oil with anti-wear and anti-adhesion additives.It greatly reduces friction, tool bonding and edge wear.

 

Stainless steel has high ductility and deformation.The bottom hole diameter should be enlarged by 5%–10% compared with standard carbon steel holes.It reduces cutting load and extrusion pressure, and fundamentally avoids tap locking.