Finish‑turning slewing bearing raceway by CNC vertical lathe. Precision pre‑machining operation before heat treatment for external‑toothed slewing rings, control raceway geometry, roundness and run‑out for heavy‑duty rotating equipment.
Finish‑Turning Slewing Bearing Raceway on CNC Vertical Lathe (Pre‑Heat‑Treatment Machining)
Manufacturing a high‑performance slewing bearing requires strict control over every machining step. Among all production procedures, raceway finish‑turning on CNC vertical lathe is one critical pre‑heat‑treatment process that directly impacts final service life, rotating smoothness and load‑carrying capacity of slewing rings.
In this 12‑second on‑site workshop video, we show our CNC vertical lathe performing finish‑turning for an external‑toothed slewing bearing. The outer gear teeth of this slewing ring have already been completed. The lathe tool feeds precisely to machine the inner raceway groove, where steel balls or rollers will run after assembly.
What we achieve in this finish‑turning operation
1. Precise raceway contour forming
We machine the raceway groove to drawing dimension, leaving uniform small grinding allowance for subsequent grinding process after quenching heat treatment.
2. Control geometric tolerance
Strictly control raceway circularity, flatness and axial run‑out. Poor raceway geometry will cause uneven force distribution, noise and premature wear during slewing bearing operation.
3. Stable clamping for large‑size workpieces
Large diameter slewing rings are firmly clamped by multiple pressure plates on vertical lathe chuck to eliminate cutting vibration. Vibration during turning will produce bad surface texture and destroy raceway precision.
Where does this step sit in the full slewing bearing production workflow
Forged blank → Normalizing / Quench & Temper → Rough turning → Raceway finish turning (this step) → Raceway induction hardening (heat treatment) → Raceway precision grinding → Mounting hole drilling → Inspection & assembly
Important note: This finish‑turning happens before heat treatment. We do not reach final raceway surface accuracy in this step. Heat‑treatment quenching will bring minor deformation, so finish grinding after hardening is indispensable for heavy‑duty slewing bearings.
Why raceway quality matters for your equipment
The raceway is the core functional surface of slewing bearing. It bears dynamic load continuously for cranes, excavators, aerial platforms, mining machinery and wind power equipment.
If turning precision is out of tolerance, even premium 42CrMo material cannot deliver expected service performance. Many early‑failure cases of slewing rings trace back to insufficient raceway machining in pre‑heat‑treatment phase.
Our production capability
We produce external‑toothed, internal‑toothed and non‑toothed slewing bearings. Every raceway undergoes strict CNC finish‑turning before hardening, followed by induction quenching and precision grinding. Full dimension and geometric tolerance inspection is carried out before delivery.
If you are looking for reliable heavy‑duty slewing bearing supplier, feel free to send us your drawing or requirement for quotation.