Legislation aimed at lowering vehicles’ CO2
emissions is driving innovation. The global automotive industry must reduce
fuel consumption and exhaust emissions, which in turn is driving an
industry-wide effort to downsize engines. That has to happen without affecting
the car’s performance.
Turbocharger is used to boost the power
output of the engine and is driven by the exhaust from the engine.With the
growth in vehicle production all around the world, the market for turbocharger
is also estimated to grow at a compound annual growth rate (CAGR) of 10.21% by
value from 2015 to 2020, a MarketsandMarkets report said.
Hot environment gets hotter
Downsizing offers 20-40% fuel efficiency
over naturally aspirated engines with the same horse power. Honeywell Turbo
Technologies, a leader in turbocharging, estimated that there will be 49
million turbocharged vehicles sold in 2019, around 43% of total car sales in
The megatrend of downsizing in engine
compartment has raised charged-air temperatures to a permanent 210°C with peaks
of 230°C at pressures of 3.3 bar, compared with maximum 200°C at pressures of
around 1.5 bar 10 years ago.
With more and more turbocharged vehicles on
the road, material suppliers is working with automakers to identify
opportunities in lightweight engines while developing materials that can
withstand the increased heat and pressure created by a turbocharger’s
Hot charge air ducts are common features in
turbocharged engines. They transfer hot compressed air from the turbocharger or
the supercharger to the intercooler.
This air is very dense and very hot, so it
is passed through the intercooler, where it cools and gains even higher density
before entering the engine. The presence of this compressed air makes the fuel
burn more efficiently, thereby delivering greater power while consuming less
The ducts obviously need to withstand very
high temperatures for long periods. Material innovations mean metal components
can now be replaced with plastic parts in the charge air system of the
Withstanding 240°C of heat
BASF offers polyamides (PA) for the various
temperature requirements of the charge-air duct. The range comprises PA 6, PA
66 and PA 66/6 grades with glass fiber content between 30-50%. The upper end of
the temperature range is covered by Ultramid Endure.
“With Ultramid Endure we have a thermoplastic
that can withstand temperatures of up to 220°C and peaks of up to 240°C without
degradation and it offers the automakers more design flexibility and the
opportunity to easily integrate other components, like the surge valve and
sensors,” explained Scott Schlicker, Powertrain Market Segment Manager at
BASF’s Performance Materials group.
Possible applications include all
components of the charge air system, according to the company. For example,
Ultramid Endure D3G7 with 35% glass fiber reinforcement and D3G10 with 50%
glass fiber reinforcement are suitable for injection molding. They are proven
to work well in air intake manifolds of turbocharged diesel engines as well as
in resonators and sensors.
Another grade, Ultramid Endure D5G3 BM with
15% glass fiber, which is suitable for blow molding, is being used for
production of charge-air pipes.
Taking process efficiency into mind
Apart from reducing emission, car makers
continue to develop the design of the charge-air duct to make the installation space
Besides that, in order to handle movements
of the engine relative to the cooler that is fixed on the chassis of the car,
and because they need to be easy to install, flexibility is an important
The current standard practice is to use
ducts with a central section in a rigid high temperature thermoplastic or metal
and end sections in a thermosetting polyacrylate, ethylene acrylic or fluoro
rubber with a woven reinforcement.
There are several disadvantages associated
with this approach, particularly in relation to weight and cost. Assemblies
based on these thermoset rubbers are heavy, because their relatively low
mechanical performance dictates the need for thick walls to be able to handle
the demands of the hot charge air duct.
In addition, total system costs of
rubber-plastics or metal-rubber solutions can be quite high, for various
reasons. The production process is a multi-step one: molding of the various
elements, followed by assembly, which adds costs and takes extra time. It also
introduces extra opportunities for defects to be introduced, both during
production and in use.
To reduce the risk of failure due to creep
at the joints in these assemblies, reinforcement rings are placed inside the
tubes, meaning another assembly step. Also taken into account is the fact that
rubber is difficult to recycle, while high energy consumption during processing
leaves a question mark over its sustainability.
DSM said its new Arnitel HT thermoplastic
copolyester elastomer (TPC) eliminates all the advantages associated with
plastics-rubber and metal-rubber combinations.
Arnitel HT is able to withstand continuous
operating temperatures of up to 180°C and peaks of up to 190°C, an unmatched
temperature resistance among thermoplastic elastomers (TPE). It also has good
resistance to the sorts of oils and chemicals commonly found in a car’s engine
Most importantly, Arnitel HT’s combination
of elasticity with high mechanical strength means that it can be used to
produce the entire duct in a single piece, using 3D suction blow molding. Wall
thicknesses can be approximately halved.
“Ducts produced in Arnitel HT can
withstand the internal operating pressures which are demanded by car producers,
not only for models in production today but also for upcoming generations,”
said Kurt Maschke, Global Segment Manager Air/Fuel at DSM.
“And by using a single solution based on a
material with excellent mechanical performance and a relatively low density in
an optimized design, it is possible to obtain weight savings of as much as
Combining water cooling is possible
To improve the cooling effectiveness of
turbocharged engines, DSM and German automotive supplier Mahle have jointly
developed the word’s first high volume use of plastic in an air intake manifold
(AIM) that integrates a water-cooled charge air cooler (CAC).
Using DSM’s PA 46, Stanyl Diablo OCD 2100,
Mahle is producing an AIM/CAC combination for BMW’s B48 engine.
Liquid is a more effective mean to cool the
air instead of air-to-air cooling. CAC integration also reduces the air duct
length, thereby improving engine responsiveness and reducing turbo lag.
“Such a design can drive the AIM’s
continuous operating temperature up to 220°C, which in turn boosts the
mechanical demands on the materials used in those components. This new geometry
also requires materials with robust weldability and weldline aging resistance
in order to maintain the part’s integrity. The Stanyl Diablo fulfilled all
customer requirements,” noted Valecka, Project Manager Integrated Manifold BMW
B48 at Mahle.
Stanyl Diablo OCD 2100 offers superb weld
strength and ensures part integrity under pressure pulsation loads. DSM said it
outperforms competitive materials in regards to thermal oxidative stability,
maintaining high stiffness at elevated temperatures and pressure loads.
Wide processing windows for hollow parts
Targeting the growing turbocharged engine
market, German specialty chemicals company Lanxess has recently rolled out two
new pseudoplastic PA for 3D suction blow molding of air ducts – the PA 66
Durethan AKV 320 Z H2.0 and the polyamide 6 Durethan BKV 320 Z H2.0.
“This innovative product is our response
to the growing trend toward turbocharged engines. These represent a growing
share of the market because they reduce a motor vehicle’s fuel consumption and
thus its CO2 emissions,” explained Thomas Olschewski, Blow Molding Applications
Expert at Lanxess.
Until now, the Lanxess product range for
suction blow molding encompassed a PA 66 reinforced with 25% glass fibers, two
non-reinforced PA 6 compounds, and two PA 6 grades with a glass fiber content
of 15% and 25%.
The two new materials each have a glass
fiber content of 20%. Their high melt strength prevents an extruded preform
from sagging under its own weight prior to inflation in the mold. The wide
processing window ensures that the inside surfaces of charge-air tubes, for
example, are extremely smooth so that the air achieves streamlined as opposed
to turbulent flow.
“With these new products, we are closing a
gap in the range to give our customers greater latitude in terms of stiffness
and strength when designing blow-molded hollow parts,” says Philipp Otte,
Product Developer for Durethan blow molding products at Lanxess.
Another advantage of these compounds is
their high resistance to the media typically encountered in the engine
compartment, such as oils, fuel and condensates of acidic blow-by gases.
“In terms of chemical resistance, our two
materials are superior to thermoplastic polyester elastomers, from which parts
like clean air ducts are also sometimes fabricated,” said Otte.
The heat-resistance race
Apart from hot air ducts, certain parts of
a turbocharged engine are made of high performance plastics, such as
intercooler end caps and resonators. The Italy-based RadiciGroup highlights its
Radilon HHR PA 6.6 for such applications.
Offering heat resistance of up to 210°C,
they are suitable for injection and blow molding with 15%, 20% and 35% glass
A new line, RADILON XTreme, has been added
to extend the company’s offering of high temperature resistance plastics for
air ducts, EGR heat exchanger components and resonatros. It can withstand
continuous operating temperatures of up to 230°C.
Radici looks to benefit from the stably
rising North American automotive market. In 2015, more than 17.4 million light
vehicles were sold in the region, beating its previous record set in 2000.
“For us, the North American auto market is
the number one market in terms of volume,” said Gianluigi Molteni, Marketing
& Business Development Head of Radici Plastics Americas & Pacific. “In
2015, we had double-digit growth versus the previous year, and our development
pipeline is strong.”
Swiss polyamide supplier EMS-Grivory has
also expanded its range of high heat resistance portfolio with the introduction
of Grilon TSG-W3.
This new material is able to withstand heat
ageing of up to 230°C. The Grilon TS XE 16002 (TSG-35/4 W3) grade, for example,
still maintains 75% of property values for tensile strength at break after
3,000 hours at 230°C. This means that its heat ageing resistance is equivalent
to that of high heat stabilized polyphthalamides (PPA).
In addition, the superior surface quality
reduces pressure loss in the charged air system and makes post-treatment on
sealing sections unnecessary, the company said.
EMS-Grivory’s previous offerings of high
heat resistance grades, Grilon TSG-W and TSG-W2, cover up to 190°C and 210°C
respectively. Grilon TSG-35/4 W2, for instance, was selected by Mann+Hummel for
production of selected resonators.
Elastomers on the same page
It is not only plastics that are gearing up
for this temperature challenge. Elastomers and rubbers used for sealing,
bushings and valves are constantly evolving as well.
A turbocharging system supplier has chosen
DuPont Vespel bushings to improve the reliability and durability of its
pneumatic wastegate actuators used in many turbocharger applications.
Wastegate actuators control the pressure of
the exhaust gases entering the turbocharger on increasing engine speed, and
controlling them exactly according to the particular driving situation.
The actuator is situated close to the
turbine of the turbocharger where exhaust gas temperatures – which can reach as
high as 1,050°C – as well as limited packaging space result in very high
actuator temperatures of more than 220°C.
As the turbocharger producer reported,
extensive tests had shown that alternative material solutions such as bushings
made of engineering thermoplastics failed at these high temperatures.
DuPont’s Vespel SP-21 has a heat deflection
temperature of 360°C, has no melting point and retains its properties under the
long-term effect of heat, even in contact with aggressive exhaust gases.
tests found that Vespel SP-21 bushings ensured that the operation of the
sliding shaft remained consistent during the entire test cycle, ensuring
accurate control of the turbocharger at different pressures and engine speeds.
Dreaming of an all-plastic engine
Solvay supported automotive light-weighting
by participating in the Polimotor 2 all-plastic engine project led by Matti
Up to 10 metal engine components –
including the water pump, oil pump, water inlet/outlet, throttle body, fuel
rail, cam sprockets and others – will be replaced by high performance polymers.
The engine typically is made of metal and
the single heaviest part in a car. Polimotor 2 aims to develop an engine
weighing 63-67kg, or about 41kg less than today’s standard production engine.
Torlon polyamide-imide (PAI) to replace
conventional metal in the fabrication of cam sprocket design. In practical
terms, this allows the Polimotor 2 cam sprocket to deliver comparable
mechanical properties with a 75% weight reduction over a similarly sized
stainless steel cam sprocket that weighs 1.1kg.
Ryton polyphenylene sulfide (PPS) for fuel
rail in fuel injection system. Replacing steel with a high performance
thermoplastic not only allowed the fuel rail to be injection molded as a single
piece, it also enabled 25-30% reduction in part weight.
KetaSpire polyetheretherketone (PEEK) for
3D-printed fuel intake runner. Replacement of the original aluminum runner with
PEEK reduced the part’s weight by 50%.
Amodel polyphthalamide (PPA) selected for
the water inlet/outlet fixture due to strong hydrolytic stability, strong
corrosion resistance and weight reduction benefits.
Tecnoflon PL855 fluoroelastomer (FKM) to
ensure tight, reliable seal o either end of the water inlet/outet.
AvaSpire polyaryletherketone (PAEK) will
form three sections of the Polimotor 2 engine’s external dry sump modular oil
pump housing. Each of the three injection molded sections weighs 0.09kg
compared to 0.19kg for their aluminum counterparts.