Under-the-hood | automotive
and the integrated cooling system. “These structural parts are exposed to liquid cooling
at elevated temperatures so it is important that they be formed with materials that can retain their mechanical and electrical properties for the life of the vehicle,” SABIC notes. The frames retain and support pouch-style lithium-ion cells, as well as cooling fins and elastomeric gaskets, helping to hold the entire pack together and provide a hermetic seal for the cooling liquid. SABIC says the design and materials change
The company first highlighted this application on the
2013 version of Nissan’s plug-in Leaf and, in the meantime, the solution has been adopted by other vehicle manufacturers. To help Nissan address this challenge, SABIC’s Innovative Plastics business supplied Noryl N1150 for the terminal cover and spacer of the battery system on the 2013 Leaf. SABIC says that by using Noryl in the updated EV,
Nissan was able to cut part weight and enhance the quality of the battery pack. The updated Leaf is 80 kg lighter than the previous model, thanks to changes to the powertrain, integrated functions, a streamlined battery module and case structure and the use of lighter parts. The terminal cover and spacer of the battery system is 20% lighter. “Use of this material in battery
parts for EVs and hybrids has contin- ued to grow and several models now use the resin in this application space,” says a representative for SABIC, citing two examples, the electric version of the Ford Focus and the Volkswagen Touareg hybrid. Noryl GFN (GFN indicates glass reinforcement) is used for the battery housing on the Focus, SABIC says, because the material enables thin-wall moulding to free up space for more battery cells. The combination of thin-wall design and low specific gravity of the Noryl GFN grade reduces weight by 15%, compared to alternative candidate materials based on such polymers as polyamides and PBT, the company claims. On the Touareg, by replacing die-cast aluminium
Noryl reduces weight by 48%, provides design freedom to integrate air temperature control, and eliminates costs associated with stamping and machining aluminium. General Motors, meanwhile, has achieved weight savings without loss of performance by shifting from a polyamide/steel combination to all-Noryl (SE1G- FN2) for the battery frame and end-frame of the Chevrolet Spark EV. The frames encase the battery
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reduced the frame weight by 13% while still allowing for tight dimensional tolerances over time. It says the dimensional stability is up to 5% better than other candidate materials, and can also deliver up to 40% better property retention over a component’s service life, despite a humid environment, fluctuating tempera- tures and pressures exerted by the cells onto the battery module.
Upgrading PP compounds It is not only engineering plastics that are seeing their potential increase in under-the-bonnet applications. At the VDI Plastics in Automotive event in Mannheim in March, for example, PolyOne announced development of reSound NF natural fibre-filled polypropylene compounds for transport applications, including parts such as battery trays, various covers in the engine compartment, air management components, and fan and shroud. PolyOne says grades, which have a minimum of 30% bio-based content, are currently being evaluated by several key automotive OEMs. Marc Mézailles, PolyOne’s
global automotive market manager for engineered materials, says adoption of natural fibre
reinforced compounds has been restricted for several reasons, including their limited mechanical perfor- mance, a lack of process consistency, and limited global availability. He says reSound NF “upends the conven- tional material property balance” and opens the industrial use of engineered natural fibre reinforced solutions in many demanding end applications, with a 5 to 10% lightweighting potential versus incumbent solutions. The material has already been approved by a leading global automotive OEM on a critical semi-struc- tural application. PolyOne describes reSound NF as a highly engi-
neered, strong and sustainable alternative to glass fibre reinforced formulations, with densities 5-10% less than comparable glass fibre formulations. Compounds make
June 2015 | INJECTION WORLD 17
Left: This Nissan Leaf battery pack makes use of Noryl PPE/PS from SABIC
Left: Sabic’s Noryl is used in this battery and frame for GM’s Chevrolet Spark EV
PHOTO: SABIC
PHOTO: SABIC
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