The slewing ring bearing housing is one of the most critical load-bearing structures on an excavator. It connects the upper carriage to the undercarriage and must absorb enormous combined radial, axial, and moment loads generated during digging, swinging, and travel—while maintaining precise geometry for the slew ring bearing and its internal gear mesh.
Ningbo Ruican manufactures slewing ring bearing housings using the silica sol investment casting process in 42CrMo4 (AISI 4140 equivalent) alloy steel, followed by finish CNC machining of the bearing bores, bolt-hole patterns, and gear mounting faces. The investment casting route delivers a near-net-shape housing with uniform wall sections and uninterrupted grain flow, avoiding the internal defects and directional weakness associated with welded fabrications or rough sand castings.
Every housing is supplied in the fully heat-treated condition (quenched and tempered to 269–302 HB) with machined surfaces inspected on CMM against customer drawings. Whether you are building 20-ton, 30-ton, or 40-ton class excavators—or servicing the aftermarket—we produce to your drawings and volumes.
Key Specifications
| Parameter | Specification |
|---|---|
| Material | 42CrMo4 alloy steel (AISI 4140 / DIN 1.7225 equivalent) |
| Manufacturing Process | Silica sol investment casting + CNC machining |
| Heat Treatment | Quenched & tempered, 269–302 HB (adjustable to requirement) |
| Casting Tolerance | ISO 8062 CT5–CT6 (machined critical features per drawing) |
| Typical Weight Range | 80–350 kg per housing |
| Surface Finish | Ra 1.6–3.2 µm on machined faces; shot-blasted as-cast surfaces |
| Inspection | CMM dimensional check, UT/MT crack detection on request, EN 10204 3.1 material certificate |
| MOQ | Negotiable—prototype to serial production volumes |
| Applicable Machines | 20–40 ton excavators, material handlers, demolition machines |
Why the Slewing Housing Demands Investment Casting Quality
A welded housing introduces HAZ (heat-affected zone) weakness exactly where fatigue cracks initiate. Sand castings in this size class often carry slag inclusions and porosity that only appear after rough machining—scrapping the part late in production. Investment casting with silica sol shells produces cleaner steel with lower gas content, and our in-house densitometry and hardness checks on every heat lot catch anomalies before machining begins.
Why Choose Ningbo Ruican
- 17+ years of investment casting for construction machinery OEMs and tier-1 suppliers
- IATF 16949 certified quality management—PPAP documentation available for automotive-linked programs
- Integrated casting + CNC under one roof: no split responsibility for critical dimensions
- Alloy flexibility: 42CrMo4, 34CrNiMo6, cast steels to ASTM A216 WCB, and ductile irons on request
- Export experience: shipments to Europe, North America, and Asia with full material traceability
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