A shaft bushing—also known as a sleeve bearing, journal bearing, or plain bearing insert—is a precision-engineered interface between a rotating shaft and stationary housing. Unlike rolling-element bearings, our CNC-machined bushings operate on sliding friction principles, offering superior performance in oscillating motion, high-impact loads, and harsh environments where sealed ball bearings often fail.
Our solid-bar stock CNC process eliminates the porosity and dimensional inconsistencies found in sintered or cast bushings, delivering a homogeneous grain structure suitable for applications exceeding PV values of 50,000 psi-fpm (pressure-velocity factor).
Material Selection: Optimized for Performance and Longevity
The right material is critical for bushing lifespan and reliability. We offer engineering-grade alloys for immediate CNC production:
| Material | Composition | Max PV (psi-fpm) | Friction Coeff. | Temp Range | Ideal Applications |
|---|---|---|---|---|---|
| SAE 660 (C93200) Bronze | Cu 83%, Sn 7%, Pb 7%, Zn 3% | 50,000 | 0.08–0.15 (dry) | -40°F to +400°F | Heavy-load, low-speed machinery; excellent embeddability |
| C86300 Manganese Bronze | Cu 63%, Zn 25%, Al 6%, Mn 4% | 75,000 | 0.15–0.20 | -40°F to +500°F | High-shock construction equipment; non-galling against steel shafts |
| Oil-Impregnated Sintered Bronze | Cu 90%, Sn 10% | 25,000 | 0.10–0.18 | -10°F to +200°F | Self-lubricating, maintenance-inaccessible assemblies |
| PTFE-Composite Steel | Steel backing + PTFE/Bronze layer | 100,000+ | 0.03–0.10 | -330°F to +500°F | Chemical processing, FDA-compliant food machinery |
| 4140 HT Steel (Hardened) | Fe 96%, Cr 1%, Mo 0.2% | N/A (housing) | — | -60°F to +800°F | High-temp structural sleeves, exhaust systems |
Pro Tip: For seawater or chlorine-rich environments, specify C95800 Aluminum Bronze to prevent dezincification and corrosion.
Precision CNC Manufacturing: Tight Tolerances, Superior Performance
Our CNC workflow exceeds standard catalog tolerances (ISO 3547), achieving IT7–IT8 precision for press-fit and hydrodynamic applications.
Key Precision Parameters
- Bore Tolerance: H7 (+0.015/+0.000 mm for Ø25mm) to H8
- OD Interference: n6/p6 press-fit, preventing fretting corrosion
- Surface Finish: ID Ra 0.4–0.8 μm (hydrodynamic) or 0.2 μm (dry PTFE); OD ≤1.6 μm
- Concentricity: ≤0.01mm TIR
Advanced Geometries
- Helical Oil Grooves: 45° spiral grooves for superior lubrication
- Integrated Flanges: Monolithic DIN 1494 Type C, eliminating thrust washers
- Graphite Plugging: Solid lubricant plugs for maintenance-free operation
Proven Field Performance
Case Study: Mining Conveyor Pivot Bushings
- Problem: OEM cast bushings failed under 15,000 psi static load with 50 fpm oscillation
- Solution: CNC-machined C86300 manganese bronze with hardened 4140 backing, axial grease grooves, and optimized clearance
- Results: Service life increased from 3 months to 14 months; downtime reduced by 312 hours/year; uniform 0.003mm wear pattern
Design for Manufacturability (DFM) Guidelines
- Wall Thickness: Min. 0.0625 in (bronze), 0.125 in (steel)
- Aspect Ratio: Length-to-ID ≤ 4:1 for bore straightness
- Oil Grooves: Depth 1/3–1/2 wall thickness, chamfer edges 0.010 in
- Material Efficiency: Standard bar stock reduces waste and costs by 15–20%
Quality Assurance: Verified Precision
- CMM Verification: Bore cylindricity ≤0.002 mm, flange perpendicularity ≤0.01 mm
- Material Certification: EN 10204 3.1 Mill Test Reports with spectrographic analysis
- Surface Profilometry: Ra values verified for hydrodynamic lubrication
- Compliance: RoHS/REACH; lead-free bronze alternatives available
