The water outlet, mounted to the engine cylinder head and acting as a manifold to distribute coolant from the engine to the vehicle’s cooling system, is a part typically made of aluminium due to the high-temperature environment and its complex design. The moulder MPC has found a way to replace this part by a single moulded product which eliminates the previous need for 18 machining operations and two leak paths, reduces the weight by 450g and leads to total cost savings of more than 25%. The application was the winning part of the SPE Automotive Innovation Awards in the Powertrain category.
The water outlet has ten seamless barbed ports that feed coolant to and from the transmission cooler, throttle cooler, heater core, oil cooler and provides coolant to the radiator. (photos: MPC)
Scientific injection moulding together with simulation brings success
The main function of the water outlet is to act as a manifold for the cooling system. It has ten seamless barbed ports that feed coolant to and from the transmission cooler, throttle cooler, heater core, oil cooler, and does provide coolant to the radiator.
The assembly is injection moulded in glass reinforced PPA.
Due to the port configurations and flash tolerance requirements conventional injection moulding practices could not be utilised. Injection moulding simulation was employed to balance the fill pattern to ensure an equal distribution of pressure; this was to prevent over-packing and to avoid gas entrapment on this complex part geometry. Scientific moulding, such as the employment of transducers to activate valve gates, helped to collect further information. Finally, through precision timing of multiple valve gates and multiple slide actions before and during mould opening, it was possible to produce seamless barb joints and to properly form this complex product in one-piece. And the precise timing of two valve gates and multiple slide actions allows for the part to properly form. The moulding process was combined with a robot to monitor and remove non-conforming products.
Compared with a metal version, the PPA water outlet is said to reduce the weight by 450g and to lead to a more than 25% cost saving.
Tightest tolerances right out of the mould
The result is an injection moulded part with ten male ports that does not have a parting line. The produced part achieves machined metal tolerances right out of the mould without any secondary machining processes. It incorporates a press-in place seal, sealed threaded insert, a wire harness bracket, an oil drip rail, and does also house the thermostat.
It is further anticipated that the injection mould tooling will last for five years based on annual volumes of approximately 800,000 pieces. Traditional cast aluminium tooling needs replacement after approximately 100,000 cycles. The part was developed in cooperation with the toolmaker Industrial Molds, material supplier Solvay Specialty Polymers and Nissan.
www.mpc-inc.com
