Why Does Heat Treatment Of Rack and Pinion Gears Matter?

Posted On Aug 10, 2018 By Fine Line Automation

Heat treatment is the standard for gear racks on industrial grade equipment, but it’s rarely found on less expensive machines. Most entry-level machines use gearing with no heat treatment.

Heat treated rack has improved surface hardness that resists higher contact stresses and allows you to push your machines harder and faster. Heat treated gear rack will wear less and last longer than an untreated rack.

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Precision Gear Rack

How Our Racks Are Treated

Our racks are treated through a process called Induction Hardening. This treatment functions as a case hardening treatment, which produces a hard outer case and a soft inner core.

The hardening process involves using a large coil to heat the rack. After heating the gear rack is plunged into an oil bath to cool (quenching). After quenching, the surface hardness is generally between 54-60 HRC with an internal hardness closer to 30-33 HRC. Only the surface of the rack is treated because if the core of the rack was hardened the rack would be very brittle and fail.

To further reduce the brittleness of the rack, the quenched rack is then heated in a controlled manner to a temperature below its "lower critical temperature" (tempering). The tempering process essentially trades some hardness for toughness. This results in a final hardness of 48-53 HRC. For comparison, standard untreated mild steel has a hardness of 15-20 HRC.

The Bottom Line

Heat treatment is the standard for gear racks on industrial strength equipment, which is why our gear racks are heat treated. The improved surface hardness resists higher contact stresses and allows you to push your machines harder and faster. The softer core and tempered outer layer mean the rack has excellent bending fatigue strength and impact resistance and will last through long use. Your gear rack will wear less and last longer than an untreated rack.

Our Heat Treated Gear Racks Are Back In Stock!

We now offer 72in, 54in, and 28in lengths. Each rack has a mounting hole pattern that takes 5/16 or M8 cap screws and mounts directly to 15 series aluminum extrusion or steel frames without special clamps.

Get Our Heat Treated Gear Racks Today


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