Seeking Methods for Repairing Industrial Gears

Technology Wanted:
Seeking Methods for Repairing Industrial Gears

Status: Completed
Award: $2,500 referral fee for each accepted lead.
An accepted lead is a lead that the client decides to follow up on with direct contact with the technology owner.

A client is seeking technologies for repairing alloy gear either on site or at a local workshop with minimal facilities.


Industrial gearboxes are deployed in various applications, like mills, belt conveyors, mixers, fans and other equipment in steel plants, mines, the tire industry, and many other applications. Due to the importance of the process, once a gearbox defects, this will create a bottleneck in the entire process, causing wasted time and money to replace the gear or the whole gearbox. Independent from the field of deployment, we need to find a technology/method/solution to repair damaged teeth inside industrial gearboxes in place.

In industrial gearboxes with spur/helical/bevel or herringbone gearing, teeth are mostly made out of alloy steel of 18CrNiMo7-6 as per DIN EN 10084 or equivalent and case hardened to 58 to 63 HRC. Gear teeth can be damaged on the surface or can be cracked and broken. This can happen from improper maintenance, errors in manufacturing or improper operation. Assuming only improper maintenance (which may cause broken teeth, damage to the surface, or anything that makes the teeth pitted or broken), we seek to find a way to repair the damaged gears to put them back in service with minimal downtime. In other words, a solution to repair the existing gear (e.g. by applying some material on damaged surfaces, or by pasting the broken parts and filling the space with some material), or any other way that avoids the need to make a completely new gear is desired. Preferably the solution must be able to be performed on site or at a local workshop with minimal/low facilities.

Some existing methods involve grinding sharp edges of damaged teeth or by welding broken teeth with arc welding. Grinding sharp edges does not fill the holes from pitting so the total contact area will not correctly meet the original specifications. Consequently, the stress will be on a smaller surface area than for the original gear, it therefore will be overloaded and the surface damages starts to increase again. On the other hand, arc welding of broken teeth will cause deformation due to very high temperature of welding and it implies effects on material properties like case hardened of tooth flank. This way is not desired in general.

Out of Scope

  • Methods that involve grinding sharp edges
  • Welding broken teeth with an arc welder

Gear manufacturers mostly prefer to get orders for new gears rather than repairing the existing damaged ones. If the repair proposed solution does not completely satisfy the technical specifications of original gear, then it is not of interest. Shutdowns, further repairs or overhauls are costly for such cases.


The technology or method we seek must:

  • Assure that the repaired gear will meet the required specifications for gear teeth geometry and metallurgic properties. Gear rating thereafter must be capable of same original with max 5% tolerance.
  • Not require tooth profile involute grinding by means of CNC grinder machine after repair because customers mostly do not have this machines onsite. This applies to hobbing machines as well.
  • Be economically justifiable. That is, the cost of repair shall be much lower than the costs of manufacturing a new gear.
  • Be quick. Preferably the time required for the treatment or repair must be as short as possible, because the shutdown of gearboxes causes significant effects on production capacity.
  • Not be logistically complex or expensive. It should be as portable as possible.
  • Preferably not be invasive to the environment and communities, not in terms of the used materials, procedures, and residues. It shall not produce any contamination or by products (acoustic, gas, liquids, etc…)
  • Be sustainable and durable. That is after the repair, the gear must perform without problem for at least 2-3 years under the same noise/temperature and vibration conditions of the original gear by max 5% deviation.
  • Preferably be repeatable providing accurate and reproducible results with maximum 5% deviation in rating/ performance parameters like vibration/noise & temperature.
  • Be easy to operate (power requirement: no need to connect to a central grid. Operators required: can be done by 1 or 2 technician after training.

The seeker's priority is to find a solution which has already been proven or may be already in use or at least in adjacent areas. Prototypes and proof-of-concept solutions are also welcome. Theoretical solutions are not of interest.