Polyaryletherketone PEEK™ Polymer For The
industry constantly strives to increase the performance level
and minimise the weight of in-engine components. Therefore, thermoplastic
materials are often used to replace parts of the engine which
are traditionally constructed from metals. The Polyaryletherketone
PEEK™ polymer is the leading high performance thermoplastic
for automotive applications. It combines outstanding tribological
performance with excellent mechanical properties over a wide temperature
Tribological performance may be defined
as the friction and wear of interacting surfaces in relative motion.
Therefore, the tribology of dry and lubricated contacts is critical
for the operation of internal combustion engines. PEEK™
polymer has excellent friction and wear properties which are optimised
in the specially formulated tribological grades, namely. 450FC30
and 150FC30 PEEK™ polymer. These materials feature optimum
levels of PolyTetraFluoroEthylene (PTFE) and a graphite solid
lubricant to reduce the value of the coefficient of friction,
with carbon-fibre reinforcement to enhance mechanical properties.
Most automotive applications
are required to operate at temperatures in excess of 120°C.
Therefore, a high continuous operating temperature (260OC, UL746B)
and excellent mechanical properties at this temperature make PEEK™
polymer the natural choice. Figure 1 gives a general overview
of the physical properties (low, medium or high) critical for
material selection in the automotive industry.
Although at PEEK™ polymer materials
are easily processed using conventional moulding equipment, an
easy flow 150FC30 PEEK™ polymer grade is available.
A detailed tribological
evaluation of PEEK™ polymer is available upon request.
The distributor rotor arms for some high performance cars such
as the Ferrari Testarossa are commercially manufactured from PEEK™
polymer. During operation the component rotates at up to 3500
rpm with 12 charge and discharge cycles per revolution. Due to
the nature and position of the application, additional fatigue
stresses are imposed on the sample by uneven road surfaces and
engine vibrations, whilst conducted heat from the engine means
that during operation the component experiences an average temperature
The rotor arm comprises a thick-walled
moulded section of PEEK™ polymer with four metal inserts.
These inserts become an integral part of the component by positioning
them in the tool and injection moulding PEEK™ polymer around
them thus a complex finished component may be mass-produced without
the need for additional machining. Dimensional accuracy over a
wide temperature range is crucial to the efficient function of
the rotor arm in maintaining a gap between the conducting insert
and the electrical contacts of the distributor.
PEEK™ polymer excels in such
high performance applications as it combines the required mechanical
properties with ease of processing and extends component service-lifetimes.
Magneti 5P entered full time commercial
production of these rotor arms after application based trials
and is currently evaluating PEEK™ polymer for devices such
as batteries, windscreen wipers, ignition and alternator systems.
WASHERS AND SEALS
Perhaps the most demanding in-engine automotive
applications of PEEK™ polymer are those of thrust washers
and seats for power transmissions. In a service-lifetime these
components are immersed in lubricating oil and operate over the
temperature range –7°C to 140°C whilst withstanding
dry and lubricated tribological contacts, with pressures up to
10MPa and velocities of up to 5ms-1. Under these conditions materials
must be dimensionally and thermally stable to allow the correct
flow of lubrication to other parts of the system.
polymer is used in such demanding applications because it exhibits
a unique combination of properties, which make it the natural
and cost-effective choice.
Large automotive manufacturers find that PEEK™ polymer may
often be used to replace metals as it enhances un-lubricated tribological
contacts while reducing the weight of components and production
Although the physical properties
of PEEK™ polymer are unusually high for a thermoplastic
material, it is readily processed using conventional techniques
to form components with fine tolerances, removing the need for
Due to the extraordinarily high tribological
demands required from these materials, PEEK™ polymer FC30
grades are used as they combine a low value for the coefficient
of friction with outstandingly low wear rates over a wide pressure
and velocity range.
produce shock absorber bearings for some of the large automotive
manufacturers in Germany. These bearings are metallic with a polymer
coating to enhance tribological properties and to prevent corrosion
of the substrate.
In an attempt to improve service-lifetimes
and the quality of their shock absorber coatings, Glycodur conducted
polymer compounding research using PEEK™ polymer as a base
material. After consultation with the technical team, studies
were initiated using the high flow powder grade material 150P
Due to the excellent performance
of the PEEK™ compound coatings in laboratory scale tests,
larger and more demanding controlled road tests were performed.
These experiments involved imposing the tribological contacts
sustained on an estimated car journey of 187,500 miles at an average
operating temperature of 90°C.
The success of the new bearing coatings
is such that they were fitted in a Paris-Dakar ratty car for advanced
testing in rough and unsurfaced terrain.
Formula One racing teams are constantly looking
to decrease the weight of vehicle components while improving the
overall performance. Therefore, when a new design of alternator
was proposed by the Italian automotive electronics specialist
Magneti Maretti, PEEK™ polymer was used as the construction
material. A spokesman for the company said, “What was needed
was a material that was tight yet could maintain its mechanical
strength and electrical resistance at high temperatures whilst
enduring heavy vibration”.
The material chosen
for this application was 450GL30 PEEK™ polymer, a 30% short
glass-fibre reinforced compound, as it offered outstanding mechanical
and fatigue properties. Although the volume resistivity of 450GL30
PEEK™ polymer is typical of the generic class of thermoplastic
materials (1017 W cm at 230C. IEC 93), the outstanding retention
of this property (1015 W cm at 1500C. IEC 93) over a wide temperature
range makes PEEK™ - polymer the natural choice for such
The alternator cover
is a complex component, which is formed by insert moulding with
three metal components. This indicates the ease of processing
of filled PEEK™ polymer compounds.