Plastics with good friction and wear properties

Friction

Friction occurs when there is resistance to relative movement between two surfaces. The coefficient of sliding friction is often given as a key figure for friction. The coefficient of sliding friction defines how great the frictional force is in relation to the normal force. A higher coefficient of friction means a greater frictional force. This means that the lower the coefficient of friction, the better two surfaces slide over each other.

Wear

Friction also causes wear on the respective sliding partners. Here, wear depends on material properties such as hardness and the surface condition (mainly surface roughness). Wear leads to material loss and reduces the service life of components. This can affect the efficiency of products and thus reduce performance. Thus, wear requires frequent replacement of components and leads to higher maintenance costs. 

Abrasion and adhesion

Depending on the sliding system, there are different sliding and wear mechanisms. In the case of plastics, abrasion and adhesion play a particularly important role. Abrasion means that rough surfaces of harder sliding components cause wear and material removal on softer sliding partners. Adhesion, on the other hand, depends on bonds at the surface; in particular, surface roughness and polarity play an important role in whether adhesive wear occurs.

Coefficient of friction

Coefficients of friction are often given as values in tables, but these values are always approximate because the coefficient of friction depends on many different factors (material pairing, surface, lubrication, temperature, humidity, wear, normal force, etc.), so the coefficient may differ from model tests in practice. At the very least, the system parameters of the model test should always be included.

The most accurate results are obtained from a test under real conditions. Here, too, however, it should be noted that the ratios between the test and the real application can change. 


Tribological optimum plastics

Ensinger thermoplastics, especially the semi-crystalline engineering and high performance plastics like POM, PK, PA, PPA, PTFE, PPS, PEEK or PI are considered to be very good sliding and wear materials due to their low coefficient of friction. At the same time, they are light, corrosion-resistant and ensure low noise development in sliding and friction applications.

This makes them particularly interesting for future markets such as e-mobility. They are therefore ideal for applications in which friction must be taken into account.

Most plastics also offer advantages under dry running conditions due to their abrasion resistance.

If you have specific questions about friction coefficients of individual materials, please contact our specialists.


Tribologically optimised compounds

For components that must meet tough mechanical and tribological demands, Ensinger is developing TECACOMP TRM Compounds with high strength and good sliding friction properties. Here, Ensinger’s product development focuses on the particular customer needs –  be they slide bearings, slide rails, hinges or functional plastic components in automotive industry. In each case, a perfectly tailored combination of high performance plastics and additives ensures optimum sliding properties. At the customer’s request, Ensinger will also integrate secondary raw materials/recycled or recompound materials from an external or internal source into the product development. 

Sliding-optimised TECACOMP TRM Compounds increase productivity with tribological applications. Lower friction between two sliding partners ensures less wear and thereby a longer life of the materials. But components made from tribologically optimised Ensinger Compounds do not only permit more efficient production and fewer downtimes, they also make a crucial contribution to greater sustainability. If the frictional resistance is lower, then less energy input in the tribological system is needed. In the mobility sector, reducing the friction in the powertrain can even make a measurable contribution to lower fuel consumption and lower CO2 and particulate emissions.

Carbon fibres, glass fibres or minerals increase load-bearing capacity. PTFE, inorganic solid lubricants or oil give the engineering and high temperature plastics good sliding properties. 
In particular, inorganic solid lubricants show, under certain conditions, improved friction and wear characteristics compared with materials filled with PTFE.  Additionally, the mineral-filled formulations show high toughness, high weld strength and a low tendency to creep.

Here is an example based on PEEK, where TECACOMP PEEK PVX has PTFE filler and TECACOMP PEEK XS has a mineral filler.

Compounds portfolio

Example of an application with mineral filled compound

Ensinger compounds with PTFE are the right choice for applications involving moderate loads and high speeds. TECACOMP PPS TRM XS was used for this blow-off valve.
Slide-friction optimized compounds: example air valve Divert air valve with TECACOMP PPS TRM XS

Stock shapes with good friction and wear properties


Other products and processing methods

To complement our products, we offer a comprehensive range of processing methods as well as customised profiles and tubes to meet your individual requirements for your finished part.

For detailed information, please contact us via our contact form.