Paste extrusion compounds
The enhancement of PTFE properties, especially with regard to tribological behavior and creep tendency, together with unchanged chemical resistance, proves very positive in automotive applications and in chemical process engineering — especially for parts facing high abrasion at high temperatures and in corrosive environments.
PTFE paste extrusion powders filled with Ceramer offer superior performance for seals, gaskets, slide bearings, cable insulation and abrasion-resistant tubing.
Ceramer in push-pull cables
A typical application for paste extrusion compounds is the production of tubing for Bowden gears — so-called push-pull cables, typically used in the automotive industry. Polyethylene tubing is being increasingly replaced by PTFE tubing because of the higher temperatures encountered.
In the past, PTFE tubing was normally reinforced with PPS for enhanced abrasion resistance. It was found that the abrasion resistance of push-pull cables was drastically increased by Ceramer compared to PPS. This results in safer, more reliable operation, even with insufficient or no lubrication — the push-pull cable will not rub through, in contrast to PPS.
Dramatic enhancement of abrasion resistance
Push-pull cables filled with 7% PPS were rubbed through after only about 50,000 cycles, while push-pull cables containing the same amount of Ceramer were still intact after 1 million cycles. Even reducing the amount of Ceramer by more than half, to 3%, prevented rubbing through. The wear-dependent lifespan could be raised more than 20-fold compared to PTFE/PPS compounds — all abrasion tests were carried out without any lubricant.
| Filler | Content [wt-%] | Loss of weight after 500,000 cycles | Loss of weight after 1,000,000 cycles |
|---|---|---|---|
| none | 0 | rubbed through after 30,000 cycles | — |
| PPS | 7 | rubbed through after 50,000 cycles | — |
| Ceramer | 3 | 1.6 % (23 °C) | 2.3 % (23 °C) |
| Ceramer | 7 | 0.4 % (23 °C) / 1.8 % (180 °C) | 0.9 % (23 °C) / 2.8 % (180 °C) |
| Ceramer + additive | 4 | 0.3 % (23 °C) | 0.9 % (23 °C) |
Mechanical properties of push-pull cables
Ceramer can be used instead of PPS to increase the abrasion resistance of paste-extruded PTFE tubing without any loss of mechanical properties.
| Filler | Temperature [°C] | Tensile strength [N] | Elongation at break [%] |
|---|---|---|---|
| PPS (7 wt-%) | 23 | 96 | 410 |
| PPS (7 wt-%) | 200 | 27 | 190 |
| Ceramer (7 wt-%) | 23 | 94 | 440 |
| Ceramer (7 wt-%) | 200 | 28 | 210 |