Overview
Graphite bushings are self-lubricating plain bearing components manufactured from carbon graphite materials, designed to provide reliable performance in extreme temperature, high-speed, and dry-running applications where traditional lubricated bearings cannot operate. These specialized bushings leverage graphite’s inherent solid lubricant properties to provide maintenance-free operation under conditions that would cause rapid failure of oil- or grease-lubricated bearings. OrroMFG produces precision graphite bushings in a variety of carbon graphite grades and impregnation options, delivering high-performance bearing solutions for the most demanding industrial applications.
Our graphite bushing product line includes resin-impregnated grades for general-purpose use, metal-impregnated grades for higher strength and thermal conductivity, and antimony-impregnated grades for enhanced wear resistance. Graphite bushings are particularly valued for their ability to operate at temperatures up to 500°C in air and even higher in inert or vacuum environments, making them indispensable in high-temperature industrial processes. They also offer excellent chemical resistance, dimensional stability, and non-galling properties. We manufacture sleeve bushings, flange bushings, thrust bearings, and custom-shaped graphite bearing components using precision CNC machining and grinding techniques to achieve tight tolerances and superior surface finishes. All graphite bushings are carefully processed and impregnated to optimize porosity control and mechanical properties for specific application requirements.
Key Features
- Extreme Temperature Resistance: Operating temperatures up to 500°C in air and up to 2000°C in inert/vacuum environments, far exceeding any polymer or oil-lubricated bearing.
- Self-Lubricating: Inherent solid lubricant properties enable completely dry-running, maintenance-free operation without oil or grease.
- Excellent Chemical Resistance: Resistant to most acids, alkalis, solvents, and corrosive chemicals, with no swelling or degradation.
- Dimensional Stability: Low coefficient of thermal expansion and no moisture absorption ensure consistent dimensions across varying conditions.
- Non-Galling and Non-Seizing: Compatible with soft mating materials and operates without seizing even under marginal lubrication or high loads.
- High Thermal Conductivity: Efficiently dissipates frictional heat, reducing operating temperatures and extending service life.
Material Specifications
| Property | Resin-Impregnated Graphite | Copper-Impregnated Graphite | Antimony-Impregnated Graphite | Carbon-Graphite (Unimpregnated) |
|---|---|---|---|---|
| Density (g/cm³) | 1.70 - 1.85 | 2.30 - 2.60 | 2.20 - 2.50 | 1.50 - 1.70 |
| Compressive Strength (MPa) | 80 - 120 | 150 - 220 | 130 - 180 | 40 - 70 |
| Flexural Strength (MPa) | 40 - 60 | 60 - 90 | 50 - 75 | 20 - 35 |
| Hardness (Shore D) | 70 - 90 | 80 - 100 | 80 - 95 | 50 - 70 |
| Coefficient of Friction | 0.10 - 0.25 | 0.12 - 0.25 | 0.08 - 0.20 | 0.15 - 0.30 |
| PV Limit (bar·m/s, dry) | 2,000 - 4,000 | 4,000 - 8,000 | 3,000 - 6,000 | 1,000 - 2,000 |
| Max Service Temp in Air (°C) | 350 - 400 | 400 - 500 | 400 - 500 | 500 - 550 |
| Thermal Conductivity (W/m·K) | 15 - 30 | 50 - 100 | 30 - 60 | 20 - 40 |
| Coefficient of Thermal Expansion (10⁻⁶/°C) | 2 - 4 | 4 - 8 | 3 - 6 | 1 - 3 |
| Porosity (%) | 2 - 5 | 1 - 3 | 1 - 4 | 10 - 20 |
| Electrical Resistivity (μΩ·m) | 20 - 40 | 5 - 15 | 10 - 25 | 30 - 50 |
Applications
High-Temperature Industrial Furnaces and Ovens
Graphite bushings are essential components in high-temperature industrial equipment including conveyor furnaces, sintering furnaces, glass manufacturing equipment, ceramic kilns, and heat treatment systems. They provide reliable bearing support for rollers, conveyors, and rotating mechanisms operating at temperatures where all polymer and lubricated bearings would fail. Metal-impregnated graphite grades are preferred for heavy-load high-temperature applications requiring enhanced mechanical strength.
Pumps, Compressors, and Turbomachinery
In pumps and compressors, graphite bushings serve as mechanical seal faces, wear rings, and throttle bushings where dry-running or marginal lubrication conditions may occur. They are widely used in centrifugal pumps, chemical process pumps, boiler feed pumps, and turboexpanders. Graphite’s self-lubricating properties prevent catastrophic bearing failure during start-up, shutdown, or process upsets when lubrication may be lost. Copper-impregnated graphite grades are commonly used for high-speed pump and compressor applications.
Aerospace and Aviation
Graphite bushings find applications in aircraft engines, auxiliary power units (APUs), and environmental control systems where high temperatures and demanding operating conditions are encountered. They are used as seal faces, wear components, and bearing surfaces in locations where liquid lubricants cannot be used or where contamination must be avoided. Graphite’s lightweight nature and high-temperature capability make it suitable for aerospace applications.
Chemical Processing Industry
In chemical processing equipment, graphite bushings provide reliable bearing support for pumps, mixers, agitators, and rotary valves handling corrosive chemicals. Their excellent chemical resistance to acids, alkalis, solvents, and process chemicals ensures long service life in aggressive environments. Graphite bushings are particularly valued in applications where product purity is critical and lubricant contamination must be avoided.
Power Generation
In power generation facilities including fossil fuel power plants, nuclear power plants, and renewable energy systems, graphite bushings are used in pumps, valves, turbines, and generator equipment. They provide reliable performance in high-temperature steam service and other demanding power generation applications. Graphite’s radiation resistance also makes it suitable for nuclear power applications.
Operating Conditions
- Temperature Range: Up to 500°C (932°F) in oxidizing air environments; up to 2000°C in inert gas or vacuum environments; cryogenic service down to -200°C
- PV Limit: 1,000-8,000 bar·m/s depending on material grade, mating surface, and operating conditions
- Load Capacity: Up to 20 MPa dynamic load; up to 100 MPa static load depending on grade and temperature
- Sliding Speed: Up to 50 m/s (10,000 ft/min) for properly designed graphite bearings
- Chemical Compatibility: Resistant to most acids, bases, solvents, hydrocarbons, fuels, and corrosive chemicals; not recommended for strong oxidizing agents at elevated temperatures
- Lubrication: Self-lubricating for dry-running service; performance enhanced by boundary lubrication when available
- Atmosphere Compatibility: Air, inert gases (nitrogen, argon), vacuum, steam, and most process gases
- Mating Surface Recommendation: Best with hard, polished mating surfaces (hardened steel, ceramic, or hard chrome plated, Ra < 0.4 μm) for optimal wear life
Material Comparison
| Material | Max Temp (Air) | Self-Lubricating | Load Capacity | Chemical Resistance | Cost | Best For |
|---|---|---|---|---|---|---|
| Graphite (impregnated) | 500°C | Excellent | Medium-High | Excellent | Medium-High | High-temp, dry-running, chemical service |
| PTFE | 260°C | Excellent | Low-Medium | Excellent | Medium | Low-load, chemical service, wide temp range |
| Nylon PA66 | 120°C | Good | Medium | Good | Low-Medium | General industrial, lubricated applications |
| PEEK | 260°C | Good | High | Very Good | Very High | High-temp, high-load, medical/semiconductor |
| Bronze | 200°C | Poor (needs lube) | High | Fair | Medium-High | Heavy-duty, lubricated, moderate temp |
| Babbitt | 150°C | Poor (needs lube) | Medium | Fair | Medium | Low-speed, heavy-load, lubricated service |
Choose graphite bushings when:
- Operating temperatures exceed the limits of all polymer bearings (>250°C)
- Dry-running or maintenance-free operation is required
- The application involves aggressive chemicals or corrosive environments
- Oil or grease lubrication is not feasible or would contaminate the process
- Non-galling and non-seizing behavior is critical for equipment reliability
- High thermal conductivity and dimensional stability are needed
Customization Options
- Material Grades: Resin-impregnated graphite, copper-impregnated, bronze-impregnated, antimony-impregnated, silver-impregnated, carbon-graphite, electrographite, and specialty grades
- Bushing Types: Sleeve bushings, flange bushings, thrust washers, step bushings, split bushings, segmented bushings, and custom geometries
- Size Range: Inner diameter 5mm to 500mm; length 10mm to 600mm; flange diameter up to 700mm
- Tolerance Grades: H6/H7 bore tolerances; IT5-IT7 dimensional grades; ground finish for precision applications
- Surface Finishes: As-machined, ground, lapped, and polished bore surfaces with Ra 0.2-1.6 μm
- Impregnation Options: Various resin and metal impregnants tailored to specific application requirements
- Groove Patterns: Helical grooves, circumferential grooves, cross-grooves, and custom lubrication groove patterns
- Flange Configurations: Single flange, double flange, and custom flange profiles
- Assembly Options: Graphite-to-metal bonding, shrink-fit metal housings, and custom bearing assemblies
- Secondary Operations: Drilling, tapping, slotting, and custom machining features
Quality Assurance
OrroMFG maintains strict quality control throughout graphite bushing manufacturing, from raw material selection through final inspection and packaging. Our ISO 9001:2015 certified quality management system ensures consistent product quality and traceability. We source carbon graphite materials from leading global manufacturers and conduct incoming material verification including density testing, hardness testing, and porosity analysis to confirm grade authenticity and conformance to specifications.
Manufacturing processes including CNC machining, grinding, and impregnation are carefully controlled and monitored to ensure dimensional accuracy and material integrity. Quality control inspections include bore diameter measurement using precision bore gauges and air gauges, outer diameter and length verification, concentricity and runout checking on coordinate measuring machines (CMM), surface roughness measurement, and dimensional verification of all critical features. We also perform material testing including compressive strength testing, flexural strength testing, density and porosity analysis, and thermal conductivity measurement for material validation. Application-specific testing such as wear testing on specialized tribometers, PV testing, and high-temperature performance testing is available for critical applications. All graphite bushings are supplied with detailed material certificates, inspection reports, and full batch traceability documentation. Our commitment to quality ensures that every graphite bushing delivers reliable, long-lasting performance in the most extreme operating environments.
