Why Has HSS Drill Straightening Always Been an Industry Challenge?
After quenching, high-speed steel (HSS) reaches a hardness of HRC 60+ — both hard and brittle:
- Hard: Cold straightening can’t move it; forcing it risks cracking and chipping.
- Brittle: Stress concentrates at the bend point — even slight over-force causes fracture.
- Variable: Manual heating relies entirely on experience — overheating burns hardness, underheating leaves it unstraight, and S-bends or double bends easily appear.
- People-dependent: Straightening quality is tied to veteran workers — limiting throughput, consistency, and staffing stability.
How Our Automatic Straightening Machine Solves It
Fortunately, our automatic straightening machine solves this challenge perfectly:
- Sensors automatically detect the bend location.
- Precise heating at the straightening point avoids overheating and underheating — no new internal stress is introduced during the process.
- Localized heating preserves drill hardness — HSS hardness and microstructure remain stable after straightening.
- Automatic force application with spring-back compensation delivers a high first-pass yield, reducing repeated straightening.
The induction heating and temperature measurement pair is the heart of the solution. Cold pressing a HRC 60+ section is a coin flip between no movement and a crack; heating the bend point locally, to a measured temperature, moves the material into a state where controlled correction is possible without disturbing the hardness elsewhere in the flute. The machine then applies force with spring-back compensation, so the correction that survives the cycle is the correction that was calculated, not the one that looked right on the dial.
The Straightening Machine
Our Straightening Machine:
This machine is equipped with an induction heating system and a temperature measuring system.
This machine is quipped with a induction heating system and temperature measuring system
This machine is designed with 4 servo motors and 2 stepping motors.
This machine is designed with 4 servo motors and 2 stepping motors.
Machine Models for Different Drill Bit Sizes
AMS-300H straightening machine: suitable for drill bits of diameter 3-8 mm and length 80-300 mm.
AMS-450H straightening machine: suitable for drill bits of diameter 3-8 mm and length 80-450 mm.
AMS-300H straightening machine: suitable for drill bits of diameter 8-13 mm and length 100-550 mm.
Hardness Context
HSS and cobalt-alloyed HSS workpieces reach a hardness of HRC 62–66 after quenching, with markedly increased brittleness. Even a slight excess of bending force during straightening can cause drill bit fracture or micro-cracking — this is the core challenge. To address this, we have developed a specialized straightening solution for HSS and cobalt HSS workpieces that effectively resolves the cracking and fracture problem. These machines are now widely deployed throughout China, especially in the twist drill manufacturing industry.
That hardness band is why the process window is narrow in both directions. Too little heat and the press does nothing; too much and the local microstructure changes, taking cutting performance with it. Temperature measurement in the loop is what keeps every cycle inside the window, part after part, instead of trusting the color of the glow or the ear of the operator.
HSS Drill Bits Straightening Machine Videos
HSS Drill bits Straightening Machine Video:
Related Knowledge
The behavior of hardened parts under correction, and why hardness changes the whole process design, is covered in straightening hardened vs. soft parts and straightening after heat treatment. The failure mode that aggressive pressing invites on hard material is examined in over-straightening and cracking, and the process comparison between heated and cold methods in heat straightening vs. cold straightening.
For more information please contact:
whatsapp: +86-13851850644
email: john@straighteningmachinery.com
website: www.straighteningmachinery.com
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