Engineers specifying fluid transfer or motion components in demanding dry-running applications often turn to polyimide filled PTFE tube for dry running because the polyimide filler dramatically lowers the coefficient of friction while retaining PTFE’s chemical inertness. In unlubricated systems, unfilled PTFE can exhibit stick-slip behavior and relatively rapid wear when surface loads exceed 0.5 MPa. By dispersing a controlled percentage of polyimide particles throughout the polytetrafluoroethylene matrix, the resulting tube reduces dynamic friction and improves heat dissipation at the sliding interface. This style of tubing is frequently selected over unfilled PTFE when a compressor, pump, or bearing surface must slide against a mating metal or ceramic part without external lubrication. The PTFE tube with polyimide filler soft mating surface option provides an optimized balance between wear resistance and protection of softer counterfaces, reducing scoring and fretting in precision assemblies such as linear guides, valve stems, and rotating unions. As a dedicated polyimide PTFE tube manufacturer, we compound the base resin with a controlled percentage of PI particles to create a dense, homogeneous wall structure that supports tight tolerances and long service intervals. Every production lot undergoes dimensional inspection, density verification, and tribological testing against representative mating materials. For service conditions dominated by continuous oscillation or high-speed reciprocation, our low wear PTFE tube PI filled grades deliver measurable improvements in dimensional stability and surface finish retention over thousands of cycles. These improvements are particularly important in aerospace actuators, analytical instruments, and semiconductor handling equipment where unscheduled maintenance is costly and space for lubrication systems is limited. The homogeneous distribution of PI particles also minimizes void formation at the tube wall, which helps maintain consistent wall thickness under high-pressure pulsation and prevents localized hot spots that can shorten seal life.
PI PTFE tubing low friction is supplied in a range of standard and custom dimensions to match common carrier and seal gland footprints. The polyimide content can be adjusted from 5% to 25% by weight, which allows design engineers to balance stiffness, creep resistance, and wear rate against the need for conformability at the sealing surface. The matrix remains chemically resistant to most acids, bases, solvents, and oxidizing media, while the PI filler contributes higher thermal conductivity and lower thermal expansion than conventional unfilled PTFE. Below are the primary performance parameters for the standard PI-filled grades.
| Grade | PI Content (wt%) | ID Range (mm) | Wall Range (mm) | Typical Application |
|---|---|---|---|---|
| PI-10 | 10% | 2–25 | 0.5–3.0 | Low-load instrument bearings |
| PI-15 | 15% | 3–40 | 0.8–4.0 | Valve stems and linear guides |
| PI-20 | 20% | 5–50 | 1.0–5.0 | Compressor rings and pump wear parts |
| PI-25 | 25% | 5–50 | 1.0–5.0 | High-load reciprocating seals |
The average surface roughness of the internal bore is held below 0.4 µm Ra for precision grades, which reduces breakout friction and improves sealing response in pneumatic and hydraulic circuits. When paired with hardened steel shafts or ceramic coatings, the PI-filled PTFE tube maintains a stable PV limit of approximately 0.8 MPa·m/s under continuous dry sliding. This value can be increased with intermittent lubrication or when the PI content is raised toward the upper end of the range. Creep resistance under compressive loads is also improved compared with unfilled PTFE; at 10 MPa and 23°C, the total deformation after 24 hours is typically less than 4%. These characteristics make the product suitable for short-stroke oscillating bushings, rotary lip seals, and guide rings that must operate without grease or oil. For ultra-clean environments, the material can be thermally pre-aged to reduce outgassing and stabilize dimensions before final machining. Each batch is traceable to raw resin lot numbers and PI filler certificates, and final inspection includes ultrasonic wall-thickness mapping, Shore D hardness testing, and a low-speed friction check against a reference counterface. Custom PI loadings, blended fillers such as carbon or glass, and special diameters are available through our application engineering group.
