Yamawa taps for the mold & die industry are a reliable solution for obtaining high quality thread surfaces in a wide range of hard and ultra-hard materials typical of this market.
The best choice in carbide hand taps for high hardness steel is EH-CT taps which are especially designed for tapping materials in the range 45 to 55 HRC such as high alloy steels (95 MnWCr 5 KU), hardened tool steels (X 155 CrVMo12 1 KU), and tool steels (X 40 CrMo 5 1 1 KU). They can be used with machining centers with synchronous feed systems.

Yamawa carbide hand tap EH-CT

Tip diameter

The tip diameter of EH-CT taps is designed to be as close to the maximum minor diameter of the 6H internal threads as possible and it is larger than standard tips. Note that if the internal thread class is specified as “6H or class 2”, make sure to drill the bored hole as close to the maximum minor diameter of the thread tolerance as possible.
To learn more about the importance of bored hole size, read this tech tip.

The chamfer length

Chamfer length of EH-CT taps is 5 threads: set the depth of the bored hole deeper than the chamfer length of the tap.
Pay attention: if the tap starts to reverse when the chips are accumulated at the bottom of the bored hole, the chamfered threads of EH-CT tap may be chipped.

Recommended cutting speed when using EH-CT taps is about 4 m/min or lower.

When the challenge is tapping of ultra-hard materials (hardness higher than 55 HRC), we recommend using the UH-CT carbide taps.