www.ipesearch.com BEARINGS, SEALS & LUBES 19
The potential of polymer
Developments in 3D printing technologies mean there is now a whole range of high-performance
polymers with mechanical characteristics similar to those of metal – so what
does this mean for bearing design? Chris Johnson explores the plastic bearing additive
manufacturing (AM) landscape
encompasses a range of
technologies that create
3D objects by layering
materials on top of each
other. Specifically, in polymer 3D
printing, there are five common
processes: stereolithography (SLA),
fused deposition modelling (FDM),
selective laser sintering (SLS), multi-jet
fusion (MJF) and material jetting.
Each of these processes affects a
material’s microstructure, including size,
shape and orientation of the grains or
crystals. This presents various
challenges and opportunities.
3D printing gives bearing
manufacturers the design flexibility to
produce bearings with bespoke
elements and enhanced performance.
The 3D printing process is relatively
simple and doesn’t require expensive
tooling. This allows manufacturers and
design engineers to experiment with
design features that wouldn’t have
been economically viable using
conventional bearing manufacturing
Bearing manufacturers can use an
increasingly diverse range of materials
with 3D printing. For example, 3D-printed
reinforced polymers can match
or be enhanced beyond conventional
properties, which opens the door to
exciting new design possibilities.
Bowman International, an Oxfordshire-based
bearing manufacturer, used MJF
technology to produce a bespoke
‘rollertrain’ retainer using PA11 nylon.
The interlocking structure permits
room for two to four more rollers,
allowing for a 70% increase in load
capacity, as well as boasting greater
elasticity, durability and functionality.
Another barrier to innovation is
minimum order volumes. 3D printing
removes this barrier, allowing
manufacturers to provide a cost-effective
low-volume production service
— even for orders as low as ten bearing
units. 3D-printed moulds save time and
money compared with expensive metal
While 3D-printed mass-produced
bearings aren’t yet commonplace,
polymer 3D printing is making an
impact in the rapid prototyping world.
For example, in a niche concept vehicle,
3D printing may be used to achieve fast
and visually appealing prototyping.
For low-load, low-speed applications,
plastic bearings offer fantastic
performance characteristics and are
already five times lighter than their steel
counterparts. Using 3D polymer
printing processes, it is possible to
design a component that is lighter still
— by using honeycomb-like structures.
This would be very difficult and time-consuming
to achieve with traditional
machining processes. Many industries
may have historically chosen to rely on
metal lightweight innovations. However,
thermoplastics, such as carbon-fibre
and polyether ether ketone (PEEK), can
offer a feasible alternative to metal.
Opting for a 3D-printed retainer in nylon
(PA66) or another polymer material can
help reduce the weight of the whole
bearing. Carbon fibre-reinforced nylon
is one of the most popular
combinations for nylon printed
materials. It offers many of the same
benefits as standard nylon, including
high strength and stiffness, but it
produces significantly lighter
components. A 3D-printed polymer
cage may also reduce the wear on the
rolling elements, compared with a
conventional steel cage.
Is quality standard?
Friction isn’t the only performance
characteristic called into question in the
3D printing debate. In June 2018, the
Additive Manufacturing Standardisation
Collaborative (AMSC) published an
updated version of its standardisation
roadmap for additive manufacturing.
Adopting standards to mitigate and
control risks, as well as allowing more
consistent quality, are important steps
for the future of 3D polymer printing.
This is especially important for
components that are safety-critical,
such as bearings.
As with traditionally manufactured
components, 3D-printed plastic
bearings must undergo the same
rigorous testing procedures to make
sure they are fit for purpose. Crucially,
when experimenting with innovative
new designs and enhanced material
properties, it is essential that the final
application environment is carefully
considered, reaffirming the importance
of bearing specialists in industry.
In the traditional manufacturing versus
advanced manufacturing techniques
debate, the good news is that you don’t
need to pick a side. Polymer 3D printing
can be used to supplement traditional
bearing manufacturing techniques,
offering rapid prototyping and
enhanced performance characteristics
that have the potential to rival metals.
While 3D-printed bearings aren’t
commonplace just yet, the evidence is
showing that they could be in the future.
Chris Johnson is managing director
For more information:
Tel: 01993 842555
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