The next big under-the-hood application for nylon may be oil
pans, which are traditionally made from cast aluminum, stamped steel or
metal-plastic-metal hybrid constructions.
New plastic versions cut weight 40 percent or more and also
integrate functionality. German auto supplier ElringKlinger developed a design
for pickup trucks that integrates significant components of the oil-circulation
"Our selection of a particularly high-melt flow grade of
Zytel nylon resin meant that we were able to manage the long flow distances at
a comparably low injection pressure and despite some very low wall
thicknesses," says Ralf Franz, development engineer at ElringKlinger. "This, in
turn, reduces cycle times, helps preserve the tool and keeps energy costs
The multifunctional design includes the pan (measuring
approximately 550 mm long, 400 mm wide and 300 mm high), sections of the
pipeline for suction of oil from the sump, the fastening flanges for the
pressure pipelines to and from the oil filter and the oil filter flange with a
directly encapsulated oil filter thread.
Separate injection-molded parts include the two-piece cover
of the suction pipe, the double pipe for connection with the oil filter and the
cover for the oil filter flange. All of
the individual parts, as well as the polymer-encapsulated metal sieve located
in the oil intake, are connected to the pan with friction welding.
The nylon 66 from DuPont
is reinforced with 35 percent (by weight) glass fibers, creating very stiff
creep- and hydrolysis-resistant components.
The compound combines high-impact resistance over a wide temperature
range with a high resistance to lubricants, road salts and other media commonly
present in vehicles. The additional heat
stabilization enables the long-term usage of the material at temperatures of up
to 150C and makes it particularly resistant to heat aging. And as in air intake manifolds, glass-fiber-reinforced
nylon provides good mechanical and acoustic attenuation properties.
Franz says the low warpage behavior of the material is also
important because it facilitates a durable and reliable seal along the
circumference of the oil pan.
"We had to design the new polymer oil pan in such a way that
its connection to the engine was consistent with the metal construction
previously used," says Franz. "We were
thereby presented with relatively large distances between the connection
points. Thanks to the high stiffness of
the material and the purpose-made application of ribs, we managed to limit
deformation under load to the required rate despite these unfavorable
conditions, thus ensuring a constant surface pressure across the whole
Whereas the ribbing located in the upper section of the oil
pan principally contributes to dimensional stability in the seal area, the many
high ridges in the lower section are designed to absorb external impacts
caused, for example, by stones as they are thrown up from the road during
More significant impacts may also occur when the dismounted
engine is placed heavily on the floor during transportation.
For the production of the seals between the pan and the
engine, as well as for the connection of oil circuit elements, ElringKlinger uses
a highly heat- and oil-resistant ethylene acrylic elastomer.
At the National Plastics Exposition held June 22-26 in Chicago, BASF
also emphasized that oil pans are a major target of its development activities.
BASF has developed Ultramid B3ZG7 OSI, an "optimized
for stone impact" grade that equals and exceeds the performance of cast
aluminum in oil pans, says Phillip E. Wilson, the new business
development manager for engineering plastics at BASF.
The OSI material is a 35-percent glass-reinforced and
impact-modified nylon 6. It has survived a battery of experimental data showing
OSI initial cracking at 60 mph, whereas aluminum pans crack at an impact of
around 50 mph under the BASF proprietary 'stone impact' simulation testing.
showed a nylon pan incorporating a windage tray, oil pickup tube and an
integrated oil filter module. Additional benefits include weight and cost