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FEATURE MATERIALS IN DESIGN & PROTOTYPING
Driving towarDs material solutions
Polyamide, polybutylene terephthalate (PBT) and polyamide compounds
from LANXESS are offering a range of benefits for automotive manufacturers. Here we find out why...
A
s we drive towards cleaner methods of travel, electric vehicle (EV) sales are soaring. In fact according to the UK
government, 327,000 ‘plug-in vehicles’ were registered last year alone. Design opportunities for vehicles are therefore also growing, with one area being the use of plastics in their design. As an example, the technical plastic
Polyamide 66 has been used for a range of applications, however its limited availability means in recent times it is being replaced by Polyamide 6. This material has, for example, been used for the cover of an on-board battery charger that is used in an all-electric compact vehicle made by a German car manufacturer. The cover and charger have been manufactured by Leopold Kostal, a supplier of automotive, industrial and solar electrics as well as electrical connector systems.
maTerials in design
The material chosen is Durethan BKV50H3.0 from LANXESS, which is highly reinforced with short glass fibres. Durethan is the trade name for the company’s range of engineering thermoplastics based on Polyamide 6 and Polyamide 66. This large-scale application underlines the fact
that polyamide 6 compounds do not necessarily have to be hydrolysis-stabilised to be used in cooling applications with glycol-water coolants in electric vehicles, the company explains. “We assume that, in the future, Polyamide 6
products of this type will become very common in the mass production of covers and other thermal management components for electric vehicles. That is especially the case for applications such as fluid connectors or control units in the cooling system,” explained Dr. Bernhard Helbich, technical key account manager at LANXESS’ High Performance Materials business unit. Plastic components in the cooling circuit of
combustion engines have long been a domain of Polyamide 66. This is because the thermoplastic is highly resistant to hot coolants such as water-glycol mixtures. However, the requirements in the thermal management of purely electric powertrains are shifting toward lower temperatures. For all-electric vehicles, the long-term thermal resistance of Polyamide 6 compounds to water-glycol mixtures is sufficient for most of the parts, even for the significantly longer stressing times in some cases. As a result, the cover permanently withstands
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temperatures of up to 85˚C during vehicle operation, and burst loads of up to 10 bar are achieved. Long-term tests on test specimens also revealed that the mechanical properties of the compound in water-glycol mixtures hardly diminished even after 1,500 hours of storage at 110˚C and a pressure of 1.5 bar. As a result, the material met the technical requirements of the major German carmaker for the water-cooled components of its electric vehicles. The cover measures around 29cm long and
12cm wide, so has a considerable flange length. Together with a seal, the cover is screwed to the aluminium housing of the charger. In addition, the high degree of strength and stiffness shown by the polyamide 6 compound ensures that the cover meets the strict leak tightness requirements. There are, however, other advantages of
Durethan BKV50H3.0. It is easy to process and can be injection-moulded at high injection speeds; and its copper-free H3.0 thermal stabilisation does not result in electrical corrosion occurring on metallic parts in the cooling circuit. It is also resistant to oils, greases, battery electrolyte and road salt.
adas
Another area in which materials are gaining ground is in advanced driver assistance systems. ADAS are designed to improve the safety of road users and are paving the way for highly and fully automated driving. According to German statistics platform Statista, the ADAS market will achieve a volume of around EUR 28 billion (USD 32 billion) in 2023. Annual growth is expected to be 17%. Here, polybutylene terephthalate (PBT) and polyamide compounds from LAXNESS are being used. “ADAS radar sensors and their housings in
particular are an attractive field of application for our polybutylene terephthalate (PBT) and polyamide compounds,” explained Dr. Christopher Hoefs, ADAS expert at the High Performance Materials (HPM) business unit at LANXESS. “We have a wide product range that meets
the desired technical requirements for this area. These include good radar transparency and dimensional stability, good laser welding behaviour, and also excellent mechanical properties for fastening the sensors in the vehicle safely and durably.”
2 DESIGN SOLUTIONS JULY/AUGUST 2022 PBT BenefiTs
ADAS sensors monitor the entirety of a vehicle’s surroundings. Their operation is based on electromagnetic waves such as radar or laser beams (LiDAR), ultrasound or the use of imaging techniques, which has a significant bearing on the material chosen for the sensor housing. For example, it is essential for the front of a radar sensor housing, also referred to as the radome, to be permeable to radar beams. In order to minimise radiation losses, the material for the radome must have a low dielectric constant (Dk) and loss factor (Df). For this purpose, LANXESS has carried out extensive tests on numerous compounds in its range, including measurements of one-way attenuation and specific transmission and reflection as a function of frequency and material thickness. “We have numerous PBT types with Dk
and Df values that make them suitable for use with the ADAS radar frequencies of 77 to 81 gigahertz that are increasingly being used,” explained Hoefs. Depending on where the sensor is installed,
the plastic for the housing must be extremely resistant to hydrolytic degradation. With the Pocan XHR series, LANXESS has PBT compounds at its disposal that achieve Class 4 or Class 5 – the top ratings – in the stringent SAE/USCAR2 Rev. 6 long-term hydrolysis tests of the US Society of Automotive Engineers (SAE). At the same time, they are highly resistant to hot air and exhibit high elongation at break values. The compounds from the Pocan HR series are
suitable for less demanding hydrolysis stability requirements. These include the fiberglass- reinforced Pocan B3233HRLT compound, which is both transparent to lasers and highly resistant in hot and humid environments, which are usually mutually exclusive properties. “This material is very well suited to joining
housing components of radar or camera sensors cost-effectively using laser transmission welding, for example,” concluded Hoefs.
LANXESS
https://lanxess.com/en
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