Bronze-filled PTFE (40% and 60%) – bronze Teflon
Bronze-filled PTFE for guide rings, bushings and loaded hydraulic seals
Bronze powder, at 40 or 60% by mass, turns PTFE into a load-bearing sliding material: it reduces cold flow (creep), increases compressive strength and conducts frictional heat better. It is the standard material for guide rings and wear rings in hydraulic cylinders and presses, and for bushings running with poor lubrication. It loses part of the chemical resistance of virgin PTFE, because bronze is attacked by acids and ammonia.
Designations and equivalents
| System | Designation |
|---|---|
| Abbreviation (ISO 1043) | PTFE + bronze |
| Trade names | Fibracon PTFE + 40% Bronze (Roechling); POLYFLON 40BRR (Daikin, antioxidant amorphous bronze); Fibracon PTFE + 60% Bronze (Roechling); Freudenberg PTFE 177023 |
Standards by product form
| Form | Standard |
|---|---|
| Filled PTFE compound | ASTM D4745* |
| Molded rod, tube and sheet | Stock-shape manufacturer's specification |
| Guide ring tape | Manufacturer's specification |
| Machined part to drawing | ISO 2768 tolerance or as per drawing |
Composition and filler
Nominal composition by mass (stock-shape manufacturers)
| Component | Content |
|---|---|
| PTFE | 60% (40% bronze grade) or 40% (60% bronze grade) |
| Bronze powder (Cu-Sn) | 40% or 60% by mass |
| Common variant | 40% bronze + 3–5% MoS₂ |
Mechanical properties
Typical values from the stock-shape manufacturer's catalog, 23 °C (40% bronze, 60% bronze); ISO/ASTM methods as per the source
| Property | Value |
|---|---|
| Tensile strength | 40% bronze: >17 MPa · 60% bronze: >12 MPa |
| Elongation at break | 40% bronze: >200% · 60% bronze: >80% |
| Compressive strength | 40% bronze: 10 MPa · 60% bronze: 10.5 MPa |
| Hardness | 40% bronze: Shore D 59-63 · 60% bronze: Shore D 60-64 |
Typical physical and thermal properties
| Property | Value |
|---|---|
| Density | 40% bronze: 3.0-3.2 g/cm³ · 60% bronze: 3.8-4.0 g/cm³ |
| Maximum continuous service temperature | 260 °C |
| Maximum short-term temperature | 60% bronze: 300 °C |
| Minimum service temperature | -200 °C |
| Melting point or glass transition | 327 °C |
| Linear thermal expansion | 40% bronze: 98 µm/m·K · 60% bronze: 95 µm/m·K |
| Thermal conductivity | 40% bronze: 0.68 W/m·K · 60% bronze: 0.74 W/m·K |
Calculate the weight of Bronze-filled PTFE (40% and 60%) – bronze Teflon bar, plate or pipe →
Friction, wear and PV limit
| Property | Value |
|---|---|
| Dynamic coefficient of friction against steel | 40% bronze: 0.13 (dynamic, 0.8 m/s, 1 MPa, against stainless steel Ra 0.5 µm; compound 40% bronze + 3% MoS₂) · 60% bronze: 0.06 (dynamic, 0.8 m/s, 1 MPa, against stainless steel Ra 0.5 µm) |
| PV limit (pressure × velocity) | 40% bronze: 0.35 MPa·m/s (at 0.05 m/s; compound 40% bronze + 3% MoS₂ (no data at 0.5 and 5 m/s)) · 60% bronze: 0.545 MPa·m/s (at 0.05 m/s); 0.68 MPa·m/s (at 0.5 m/s); 1.02 MPa·m/s (at 5 m/s) |
| Deformation under load (creep) | 40% bronze: 8% (total deformation under 14 MPa, 24 h; 40% bronze + 3% MoS₂) |
| Deformation under load (creep) | 60% bronze: 6% (total deformation under 14 MPa, 24 h, parallel (permanent 2.5%)) |
PV and friction depend on the test method, the mating surface (steel, stainless, roughness), lubrication and each manufacturer's safety factor: compare values from the same source and confirm by testing in critical applications.
Chemical resistance
| Medium | Resistance |
|---|---|
| Acids | Limited: bronze is attacked by oxidizing acids and ammonia solutions |
| Bases (alkalis) | Good in weak bases; bronze limits use in ammonia |
| Solvents | Good |
| Hydrocarbons and oils | Good (mineral hydraulic oil OK) |
| Steam and hot water | Limited; Daikin: not recommended for water |
Stock forms and sizes
- Rod (round bar)
- Tube and bushing
- Sheet (plate)
- Guide ring tape
- Raw material: rod (round bar), sheet (plate) and tube, cut to size
- Machined part to drawing or sample, in the same order as the metal parts
- Lot certificate of conformity; FDA/EU 10/2011 declaration when the grade allows
Service temperature, machining and assembly
| Item | Usual practice |
|---|---|
| Service temperature | Continuous service up to 260 °C; minimum -200 °C (unloaded; under load, limited by HDT and creep). |
| Annealing (stress relief) | Stress-relief annealing before finish machining of tight-tolerance rings and bushings. |
| Bonding and welding | Cannot be welded; bonding only after chemical etching of the surface. Guide rings are fitted split (angle cut) or in a groove. |
| Machining | Machines like PTFE, but bronze wears the tool faster: prefer carbide. The chips are metal powder with PTFE; keep them separate from steel chips. |
Typical applications
- Guide rings and wear rings for hydraulic cylinders and presses
- Bushings and bearings with poor lubrication
- Dynamic rod seals in hydraulic oil
- Slide plates and wear strips
- Replacement for SAE 660 bronze bushings that gall
Alternatives: SAE 660 bronze when the load is very high and lubrication is good; bearing-grade PEEK for more load and temperature; carbon-filled PTFE in water, steam and media that attack bronze.
Frequently asked questions
Which standards cover Bronze-filled PTFE (40% and 60%)?
Filled PTFE compound: ASTM D4745*. Molded rod, tube and sheet: Stock-shape manufacturer's specification. Guide ring tape: Manufacturer's specification. Machined part to drawing: ISO 2768 tolerance or as per drawing.
Up to what temperature can Bronze-filled PTFE (40% and 60%) be used?
Continuous service up to 260 °C; minimum -200 °C (unloaded; under load, limited by HDT and creep).
Which materials can replace Bronze-filled PTFE (40% and 60%)?
SAE 660 bronze when the load is very high and lubrication is good; bearing-grade PEEK for more load and temperature; carbon-filled PTFE in water, steam and media that attack bronze.
PTFE with 40% or 60% bronze?
The 60% grade has less creep, a higher PV and better heat conduction: it is the standard for hydraulic guide rings. The 40% grade keeps a little more of PTFE's flexibility and is common in seals and moderately loaded bushings.
Can bronze-filled PTFE replace a bronze bushing?
In many cases, yes, especially when lubrication is poor or there is a risk of galling. Compare the PV limit and compressive strength: solid bronze carries much higher loads with good lubrication.
Is bronze-filled PTFE suitable for food contact?
Generally not: bronze is not an approved filler for food contact. For the food industry, use virgin PTFE, glass-filled PTFE or PET with PTFE.
