HITACHI AUTOMOTIVE SYSTEMS EUROPE BENEFITS FROM FLOW, STRENGTH & DIMENSIONAL ACCURACY OF ARNITE® PBT

Hitachi Automotive Systems Europe, Ltd., has selected a reinforced Arnite® polybutylene terephthalate (PBT) blend from DSM Engineering Plastics for injection moulded mass airflow sensor body destined for Audi engines. Arnite TV4 261 30% glass reinforced grade PBT provides a combination of properties important to the application, including excellent flow, long term dimensional stability, stiffness and strength over a wide temperature range and chemical resistance. Production requires only moulding – no annealing is required to relieve internal stresses that could lead to warpage.

"Throughput is excellent with this design," said Andrew Bridge, Procurement & Design Manager for Hitachi. "The ability to mould the unit in one piece without annealing saves us two production steps compared to less sophisticated, two-piece approaches with alternate materials."

The Hitachi body serves both to mount the mass airflow sensor system precisely and to shape air flow using a moulded-in grid. To control the turbulent airflow, the grid induces a laminar flow that helps ensure accurate feedback about engine air intake temperature to the engine control unit. Mass airflow sensor data help engine control systems maintain an optimum air-fuel balance.

The grid's thin-wall elements and intricate geometry benefit from Arnite's flow properties, minimising moulded-in stresses and strains that later might contribute to warpage or unpredictable dimensional change, causing the sensor to misread airflow.

The design process for the component was a collaboration involving Hitachi, moulder and toolmaker W.H. Smith & Sons, Ltd., materials and processing expert DSM Engineering Plastics and design and mold flow specialist DSM/DADC (Design and Development Centre).

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