Refurbishment of Two Worm Gearboxes from an OEM Device – When a Standard Solution Does Not Exist

Some devices are simply too critical to afford downtime. When a customer entrusted us with two worm gearboxes from an OEM device that is no longer in production, the challenge was clear: original replacement parts do not exist, and a new device would potentially mean at least 6 months of waiting and more than €100,000 in costs.

We solved this differently.

Diagnosis: Severe Wear of Gears and Shafts

After inspecting both gearboxes, we determined that the gears and worm shafts were heavily worn. Unfortunately, the gearboxes had not received regular maintenance for many years, which further escalated the challenge we now faced. Since this is a device not from serial production, replacement parts could not be ordered from the supplier.

Challenge: Non-Standard Dimensions

The larger dimensions of the gears further complicated the situation – standard manufacturing on dedicated gear-cutting machines was not possible. We needed a different approach.

Our Solution:

1. 3D modeling – Based on measurements of the existing (worn) parts, we created a precise 3D model of the new gears and worm shafts.
2. 5-axis CNC milling in-house – We milled the parts in our own workshop on a 5-axis DMG Mori DMU 50 CNC milling machine, which gave us complete control over quality and dimensional accuracy.
3. Completely new gears and worm shaft – The result is parts that ensure equal or better long-term reliability than the originals

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Comprehensive Refurbishment – All Under One Roof

In addition to milling new parts, we also performed all standard comprehensive refurbishment processes.

Oil replacement is often neglected in worm gearboxes, but it is crucial – old, contaminated oil accelerates wear and reduces transmission efficiency. Fresh oil of the correct viscosity ensures optimal lubrication and heat dissipation.

Replacement of bearings and seals is essential with every serious intervention. Worn bearings cause vibrations and inaccurate shaft guidance, while deteriorated seals lead to oil leakage and the entry of contaminants into the housing – which quickly leads to repeated failure.

Measuring bearing seat tolerances tells us whether the bearing seats in the housing are still within the manufacturer’s tolerances. A bearing seat that is too loose or too tight causes premature failure even of a new bearing, so we do not leave tolerances to guesswork. Where tolerances are no longer adequate, we restore the bearing seat – thereby ensuring that the entire gearbox after refurbishment is geometrically consistent and ready for long-term trouble-free operation.

Laser welding and shaft grinding are necessary when the shaft has suffered wear on bearing or seal seats. With laser welding, we apply material extremely precisely without thermal deformations, which are otherwise a common side effect with conventional welding. This is followed by grinding to the exact prescribed dimension.

Each gearbox was inspected after completion of all interventions and prepared for return to operation.

Result: Time and Cost Savings