Duo-Lock is the latest technology from a collaboration between Haimer and Kennametal. It is the ONLY modular system with the performance of a solid carbide end mill.

What differentiates Duo-Lock?

Competitive modular milling tools are not able to perform at the level of solid carbide end mills. Duo-Lock is the ONLY modular system capable of 1 x D full slot milling and/or 1.5 x D side milling at up to 50% radial engagement. In comparison, known competitors can offer up to 0.7 x D length of cut for roughing, and a few have the ability for 1.2 x D for finishing. Duo-Lock standard inserts have a 1.5 x D long cutting edge for roughing and finishing.

Why is the coupling so superior?

Duo-Lock combines best-in-class runout accuracy and length repeatability providing maximum coupling stability. Front support 5° cone and 1st support 10:1 cone allow axial repeatability below .0004" and radial below .0002" same insert tip in, same insert tip out. Length repeatability from insert tip to insert tip within .002".  Intelligent thread and very tight cylindrical grind permits longer length of cuts up to 1.5 x D and reduces total runout at the cutting edge to below .0004". With the repeatability of Duo-Lock, accuracy of .002" can be achieved from insert tip to insert tip, across manufactured batches and across all standard geometries.

What are The Golden Rules?

1) Clean the coupling on both sides.

2) Apply recommended torque using a torque wrench.

3) Do not clamp on the coupling.

4) Use tapered shanks for slotting.

Why is a clean coupling important?

The Duo-Lock Intelligent Thread is tailored to eliminate the force peaks all regular threads have in the first groove. This functionality works perfectly if recommended torque values are applied and the thread is free of additional lubricant such as oil, anti-seize, grease etc. The Duo-Lock Intelligent Thread evenly distributes the forces across the entire length of the thread. This allows a greater than 25% torque transmission than any other competitor. Clamping on the Duo-Lock coupling has the opposite effect than lubricant on the thread. To avoid risk of tool failure during high performance applications, clean both sides of the coupling and do not clamp on the coupling.


Please visit for the full selection of Duo-Lock products.

Key Takeaways

  • Duo-Lock is exciting new technology from Haimer and Kennametal.
  • It is the only modular system delivering the performance of a solid carbide end mill.
  • There are mulitple applications where Duo-Lock can be applied.

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Kennametal delivers productivity to customers seeking peak performance in demanding environments by providing innovative custom and standard wear-resistant solutions, enabled through our advanced materials sciences, application knowledge, and commitment to a sustainable environment.

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