Stanyl®, a high-performance polyamide 46 (PA46) resin from DSM Engineering
Plastics, was chosen for the production of tumble valve bearings for the
latest generation of the V6 and V8 engines of a high value german car
producer. Tumble valves are an integral part of the manifold, optimizing the
air flow in the combustion chamber. It is the first time that such tumble
valves have been produced by assembly molding and Stanyl® played an important
role in making this possible.
With the in-mold assembly technique, components are assembled inside the mold
in a two shot (2K) process. This results in significant cost savings compared
to traditional processes in terms of assembly, tooling, and machinery. For
in-mold assembly to work, a combination of materials is required which can
meet both the in-mold process demands as well as perform reliably under the
operating conditions throughout the life of the engine. In the molding
process, Stanyl® has outstanding stiffness at high temperatures – even close
to its melting point – which enables 2K overmolding without distortion of the
initial molding. As the assembly has a bearing function, free movement of the
two components is required after production, requiring that no adhesion occurs
between the two materials during the molding process and that shrinkage
coefficients are such that free movement is maintained after molding and at
engine operating conditions and temperatures up to 150°C.
In addition, wear and friction behavior of the component materials is very
important. The tumble valve bearings have to resist high loads which are
constantly operating at high frequency when the engine is running. Good wear
and friction properties play an important role in the lifetime of the
component itself and subsequently the engine. A grade, selected from the
Stanyl® portfolio of materials that are optimized for stiffness and improved
tribological performance, gave the right performance against the mating
material in the assembly (PPS).
“The success of this full plastic tumble valve proves the excellence of
plastics in reducing costs while providing functionality”, said Thomas Lunow,
Technical Engineering Specialist for DSM. “This solution also demonstrates the
reliability of Stanyl® in such challenging applications”.
The tumble valve optimizes the air flow in the combustion chamber and ensures
a faster and uniform distribution of the air fuel dispersal. This results in a
faster burning speed and more efficient combustion. In its turn, that supports
significant improvements on the engine’s performance as well as lowering fuel
consumption of the car, typically by 0.2 liters of gasoline per 100 km for the
same engine power. The use of tumble valve also leads to NVH (Noise Vibration
Harshness) improvements.
Schneegans GmbH a specialist for two component production and responsible for
development and realizing the total production concept (Emmerich am Rhein,
Germany), the molder of these thermoplastic tumble valves, uses Stanyl® in its
challenging assembly molding. Stanyl® played an important role by enabling
Schneegans to successfully execute this in-mold assembly technique in the
production of such a highly demanding application. The development of this
innovative tumble valve system by Schneegans was realized in partnership with
Pierburg and Mercedes Benz.
