The ball mill bearing house — also called the trunnion bearing — supports the rotating trunnion journals at both the feed and discharge ends of the mill. It carries the entire weight of the rotating assembly (shell, heads, liners, diaphragm, grinding media, and material charge). LIMING manufactures both babbitt sliding bearings (with hydrodynamic oil film lubrication) and rolling element bearing assemblies for reliable, long-life mill operation.
The bearing house is the foundation that supports the ball mill's rotating trunnion journals. These journals — hollow cylindrical extensions of the mill heads — sit in the bearing shells, which are housed in a robust cast steel or ductile iron housing. The housing is bolted to a concrete foundation and must resist tremendous static and dynamic loads while accommodating slight angular misalignment from mill shell deflection under load.
Two fundamentally different bearing technologies are used in ball mills, and the choice depends on mill size, speed, loading, and operating philosophy:
| Feature | Babbitt Sliding Bearing | Rolling Element Bearing |
|---|---|---|
| Operating Principle | Hydrodynamic oil film — the rotating journal "floats" on a pressurized film of oil | Rolling contact — balls or rollers between inner and outer races |
| Load Capacity | Very high — suitable for largest mills | Moderate to high — typically for mills up to ~3.5 m diameter |
| Wear | Zero metal-to-metal contact when oil film is established; minimal bearing shell wear | Progressive rolling contact fatigue; finite bearing life |
| Friction | Higher starting friction (boundary lubrication before film forms); very low running friction | Low starting and running friction |
| Lubrication | Pressurized oil circulation system with reservoir, pump, filter, and cooler | Grease or oil bath lubrication; simpler system |
| Cooling | Water cooling circuit integrated in housing — essential for removing frictional heat | Natural cooling typically sufficient; no water circuit |
| Maintenance | Babbitt shell relining when worn; periodic oil analysis and change | Replace entire bearing when worn; simpler maintenance |
The hydrodynamic babbitt bearing relies on a continuous supply of clean, cooled oil to establish and maintain the lubricating film. Key system components:
Proven bearing designs, quality materials, and complete lubrication system integration.
Babbitt sliding bearings and rolling element bearings — we manufacture both and recommend the optimum type for your mill.
Centrifugally cast tin-based babbitt lining with bond testing to ensure perfect adhesion to the steel backing shell.
Water cooling circuits cast or machined into the housing. Complete lubrication packages with pump, filter, and cooler available.
Self-aligning spherical seat in the housing allows the bearing shell to pivot and accommodate slight trunnion misalignment.
| Parameter | Specification |
|---|---|
| Product Type | Ball Mill Bearing House / Trunnion Bearing Assembly |
| Bearing Types | Babbitt sliding bearing, rolling element bearing |
| Housing Material | ZG270-500 cast steel or ductile iron |
| Babbitt Material | Tin-based white metal (Sn-Sb-Cu alloy, e.g., ZChSnSb11-6) |
| Babbitt Lining Thickness | 5-15 mm (centrifugally cast onto steel shell) |
| Journal Diameter | 500 mm – 2,500 mm (per mill design) |
| Bearing Load Capacity | Custom per mill size — up to 500+ tons per bearing |
| Alignment | Self-aligning spherical seat (babbitt bearings) |
| Lubrication | Hydrodynamic oil film with pressurised circulation system (sliding bearing) |
| Cooling | Integrated water cooling circuit (sliding bearing) |
| Oil Supply Pressure | 0.2-0.5 MPa (operating); up to 10 MPa (high-pressure lift during start) |
| Temperature Monitoring | RTD sensors in bearing shell — alarm and trip setpoints |
| Lead Time | 60-120 days (standard mill sizes may be in stock) |
From housing casting to final bearing assembly — precision manufacturing for reliable mill support.
Cast steel or ductile iron housing cast in sand molds with integral cooling passages and oil galleries.
CNC boring of bearing seat (spherical for self-aligning bearings) and machining of mounting and connection faces.
Steel bearing shell fabricated or cast. Bonding surface prepared for babbitt adhesion.
Tin-based babbitt centrifugally cast onto bearing shell. Bond tested via ultrasonic inspection.
Bearing shell fitted to housing. Lubrication and cooling connections tested. Final inspection and certification.