What is Fretting? | Causes, Signs, & More

When working with geared traction equipment, technicians and field service personnel are often faced with a myriad of common but highly technical wear conditions. One of the most commonly misunderstood is fretting.  If caught early enough and the cause is addressed with properly performed maintenance procedures, it’s possible to extend the life of your gear set. 

Q. What is fretting?

A: Fretting is a condition where the surface of the mating gears is subject to excess heat and wears away over time in what is often perceived to be porosity of the gear material. In fact, the condition is almost never a result of underlying material deficiency or “blow holes” as it’s commonly called. What you’re actually seeing is the after effects of the surface material work hardening and subsequently flaking off in what appear to be jagged chunks. 

Q. What are the causes of fretting?

A: Although fretting can occur for a variety of reasons, some of the most common causes are:

  • Excessive heat

  • Excessive load condition

  • Lack of lubrication

  • Shock loading typical of lost motion

In other words, if an elevator is exposed to excessive heat, runs long or stressful, overloaded duty cycles, or isn’t properly lubricated, this can result in fretting. Special concern should be paid to any type of elevator used in an undersized capacity for freight.

Q. What are the signs of fretting on gears?

Fretting appears as jagged pits on the surface of the gear face, most commonly on the counterweight-loaded side of the bronze gear. It is a telltale sign that the material is becoming fatigued or otherwise breaking down over time.

In some types of cases, this can be fixed by simply changing the lubricant. Alternatively, you may opt to replace the entire gear set, as it may be too damaged to be remedied. Keep in mind that in the case of heavy vibration or rocking, it is a good idea to eliminate some of the gear play leaving only the necessary amount of backlash and available clearance.

Key Takeaways:

  • Fretting is a term that describes the development of pits on the gear face.

  • Fretting is commonly caused by excessive loading, heat, or a general lack of lubrication.

  • Most often, there are marks on the teeth that make the material appear to be porous.

Overall, if you require a replacement gear set of advice on remedying fretting wear, Titan Machine is your reputable source for expertise on all things gear related! Contact us today for a quote, consultation, or more information on the high-quality elevator products we provide.

Monday, August 29, 2022