Self-Lubricating Construction Bearings — Factory Direct
GUNRI manufactures graphite-plugged bronze bushings, bimetallic bearings, and wear plates for excavators, loaders, bulldozers, cranes, and heavy construction equipment. Alloy selection support, custom dimensions, global shipping.
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Product Range
Every self-lubricating bearing we manufacture is produced in-house — from raw casting to final machining. Choose from standard sizes or send us your drawing for a custom solution.
Graphite-Plugged Bronze Bushings
Straight and flanged bushings with embedded graphite lubricant plugs. Alloy options: C86300 (manganese bronze), C95400 (aluminum bronze), C93200 (leaded tin bronze). ID range 10–500 mm, custom lengths available. Graphite coverage 15–30% of bearing surface.
Bimetallic Self-Lubricating Bearings
Steel-backed bearings with a sintered bronze layer impregnated with graphite or PTFE. Designed for high-load, low-speed applications where dimensional stability under shock loads is critical. Ideal for track rollers, undercarriage pivot points, and hydraulic cylinder mounts.
Bronze Wear Plates & Slide Plates
Graphite-plugged and solid-lubricant-impregnated wear plates for sliding surfaces, guide rails, outrigger pads, and linear motion applications. Available with mounting holes, counterbores, and custom groove patterns. Standard thickness 5–50 mm.
Flanged Bearings & Thrust Washers
Self-lubricating flanged bushings and thrust washers designed for axial load support in gearboxes, slew drives, and pivot assemblies. Available in all standard bronze alloys with graphite or PTFE lubrication. Custom flange diameters and thicknesses.
Custom Self-Lubricating Bearings
Built entirely to your specifications. Any bronze alloy, any graphite plug pattern (staggered, spiral, diamond), any geometry. Submit your CAD file or 2D drawing — we provide design feedback and a quotation within 24 hours. No minimum engineering fee for custom work.
Oilless Guide Bushings
Self-lubricating guide bushings for stamping dies, injection molds, and precision linear motion systems in construction equipment manufacturing. Graphite plug and bimetallic versions available with close-tolerance ID finishing.
Material Grades & Specifications
We cast and machine self-lubricating construction bearings in four primary bronze alloys. Selection depends on load conditions, impact resistance, operating temperature, and environmental exposure.
| Alloy | Type | Tensile Strength | Hardness (HB) | Max Static Load | Max Temp | Best For |
|---|---|---|---|---|---|---|
| C86300 | Manganese Bronze | 760+ MPa | 210+ | 120 N/mm² | 300°C | High-impact: bucket pins, breaker bushings, kingpins |
| C95400 | Aluminum Bronze | 550+ MPa | 180+ | 100 N/mm² | 400°C | Corrosion/high-temp: marine, chemical, concrete pumps |
| C93200 (SAE 660) | Leaded Tin Bronze | 250+ MPa | 70 | 60 N/mm² | 260°C | General purpose: moderate loads, auxiliary equipment |
| CuSn8 | Phosphor Bronze | 500+ MPa | 80+ | 80 N/mm² | 280°C | Wrapped bushings, thin-wall sliding bearings, high speed |
Graphite plug lubricant reduces the friction coefficient to 0.08–0.18 (dry) and enables maintenance-free operation. PV limit: 1.65 N/mm²·m/s with graphite lubrication. All materials available with custom graphite coverage patterns.
Applications in Construction Machinery
Self-lubricating graphite bronze bushings from GUNRI are engineered for the most demanding pivot and wear points in heavy equipment. Use this guide to select the correct material and configuration for your application.
| Machine Type | Application | Recommended Material | Key Requirement |
|---|---|---|---|
| Excavator | Bucket ear pins, boom & arm linkages | C86300 Graphite-Plugged | High impact, dust resistance, oscillating load |
| Excavator | Swing bearing, track rollers | C95400 Graphite-Plugged | Wear resistance, corrosion (mud/water) |
| Wheel Loader | Lift arm pins, articulation joints | C86300 / C95400 | Heavy load, oscillating motion, misalignment |
| Bulldozer | Equalizer bar pins, track tensioners, blade tilt | C86300 | Side loads, impact, abrasive dust |
| Crane | Boom pivot pins, slew ring bearings, outrigger pads | C95400 / C93200 | Medium speed, high static load, weather exposure |
| Hydraulic Breaker | Tool bushings, piston bushings, bracket pins | C86300 (molded sintered) | High-frequency impact, shock load |
| Concrete Pump | Swing tube bearings, hopper pivot | C95400 | Abrasion + corrosion (cement slurry) |
| Grader | Blade linkage pins, circle gear, moldboard pivot | C86300 / C93200 | Abrasive wear, dust, constant adjustment |
| Compactor / Roller | Vibration drum bearings, articulation | C95400 / CuSn8 | Vibration resistance, fatigue life |
| Drilling Rig | Feed carriage bushings, mast pivot | C86300 / C95400 | Shock, high static load, contaminated environment |
Manufacturing Capabilities
We control every step of production in our ISO 9001 facility — from raw material casting through final CNC machining and quality inspection.
- CNC turning, milling, drilling, and grinding (4-axis and 5-axis)
- Centrifugal casting (up to Ø600 mm) and continuous casting
- Powder metallurgy sintering for bimetallic bearings
- Graphite plug drilling and insertion (Φ3–Φ10 mm plugs)
- Custom plug patterns: staggered, spiral, diamond, custom grid
- ISO 9001 quality management system (certified)
- In-house hardness, density, chemical composition, and ultrasonic testing
- CAD-based design support — manufacture from your 3D file
- Surface finishing: grinding, honing, burnishing, PTFE coating
- Standard and custom packaging for export shipping
Technical Specifications
Our self-lubricating bearings are manufactured to international standards. Below are the general technical parameters for our standard graphite-plugged bronze bushing line.
| Inner Diameter Range | 10 mm — 500 mm (custom up to 800 mm) |
| Graphite Plug Coverage | 15% — 30% of bearing surface |
| Plug Diameter | Φ3 mm — Φ10 mm |
| Max Static Load | Up to 120 N/mm² (alloy dependent) |
| Max Sliding Speed (Dry) | 0.5 m/s (higher with lubrication) |
| PV Limit | 1.65 N/mm²·m/s (graphite lubricated) |
| Temperature Range | -40°C to +400°C (alloy dependent) |
| Friction Coefficient (Dry) | 0.08 — 0.18 |
| Recommended Shaft Hardness | HRC 45–55 |
| Recommended Fit Clearance | 0.3% — 0.5% of shaft diameter |
| Bushing Tolerance (ID) | F7 (standard), custom up to H6 |
| Bushing Tolerance (OD) | h7 (standard), custom up to m6 |
Why Choose GUNRI
20+
Years of Expertise
Over a decade of precision manufacturing for construction and heavy equipment applications worldwide.
OEM
Custom Manufacturing
Built to your CAD files. Any alloy, any geometry, any graphite pattern — with engineering support at no extra charge.
2–4
Weeks Lead Time
Standard custom orders ship in 2–4 weeks from drawing approval. Rush orders available for urgent requirements.
Global
Worldwide Shipping
Export to North America, Europe, Southeast Asia, and the Middle East. Factory-direct pricing, no middlemen.
Frequently Asked Questions
What materials do you use for self-lubricating construction bearings?
We manufacture in four primary bronze alloys: C86300 manganese bronze (highest impact resistance, tensile strength 760+ MPa), C95400 aluminum bronze (excellent corrosion and heat resistance, up to 400°C), C93200 SAE 660 bearing bronze (general purpose, good machinability), and CuSn8 phosphor bronze (high fatigue strength for thin-wall wrapped bushings). All alloys are available with graphite plugs for maintenance-free self-lubricating operation.
How do self-lubricating bearings work without grease?
Our bearings use graphite plugs embedded into the bronze matrix. As the bearing surface wears during operation, microscopic graphite particles transfer to the shaft interface, forming a dry lubricant film. This film provides a friction coefficient of 0.08–0.18 — comparable to grease-lubricated systems but without the need for relubrication, grease fittings, or maintenance access.
What is the typical lead time and MOQ?
Standard custom orders ship in 2–4 weeks from drawing approval. Rush orders can be expedited to 10–15 days. MOQ depends on part size, complexity, and material — small custom bushings start at 50 pieces, while larger cast components can be as low as 10 pieces. Contact us with your specifications for a precise quotation.
Can you manufacture from my drawing or CAD file?
Yes. Send us your 3D CAD file (STEP, IGES, STP) or 2D drawing (PDF, DWG) with dimensions, tolerances, and material requirements. Our engineering team reviews every submission and provides a quote within 24 hours. We also offer design recommendations for manufacturability and performance optimization.
How do I select the right alloy for my application?
Selection depends on load, impact frequency, temperature, and environmental conditions. For heavy impact and shock loads (excavator bucket pins, breaker bushings), choose C86300. For corrosive or high-temperature environments (concrete pumps, marine), choose C95400. For general-purpose moderate loads, C93200 is sufficient. For a detailed comparison of each alloy with application-specific recommendations, read our technical guide to self-lubricating construction bearings.
Do you offer samples for testing?
Yes. We provide sample bushings for field testing and validation. Contact us with your application details, load parameters, and shaft dimensions. We will recommend the appropriate material, graphite configuration, and bearing geometry — then send samples for your evaluation.
What quality control do you perform on each bearing?
Every bearing is inspected for chemical composition (spectrometer), hardness (Brinell), dimensional accuracy (CMM and go/no-go gauges), and visual surface quality. We also perform ultrasonic testing on cast components and graphite plug pull-out testing to verify plug retention under load. ISO 9001 certified production ensures full traceability.
Ready to Order Your Self-Lubricating Bearings?
Send us your specifications or drawing. We respond with a quotation and engineering feedback within 24 hours.
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