INTELLIGENT INJECTION MOULDING: TYRE PRESSURE SENSORS "FROM A SINGLE SOURCE"

Weiss produces sensor housings using the 2K process for a manufacturer of tire pressure monitoring systems. Stamped and bent parts are also integrated into the housing as transmitting antennas. They pass on the measurement data via radio.

THE TASK
The task was to design and manufacture a housing for the sensors housed in the tire. The specifications included a service life of five years and thus permanent protection of the sensitive measuring electronics, access to the pressure sensor and the integration of the antenna with which the measurement data is transmitted to the telematics unit.

THE SOLUTION
The production concept developed by Weiss begins not only with the plastic granules, but also with a delicate stamped and bent part. It serves as an antenna that sends the sensor signals to the telematics unit. It is automatically separated and placed by a robot in a 2K tool that is equipped with a turn-turn device. The 2K injection molding system first encapsulates the punched-bent part with a PBT, which the actual sensor housing is made of, and in the second process step with a soft TPE, which closes the assembly openings and forms a seal. After an automated in-line test, the housings are placed - again automatically - in the transport packaging.

SPECIAL FEATURE
Two automated in-line tests are part of the production process. One is to ensure that the hole that ensures air flow through the sensor is present and of sufficient size. The presence of the antenna in the sensor housing is also checked. The control concept is also unconventional: As a master, the robot determines the cycle of the injection molding machine, and the control allows both a start-up phase and continuous production in smaller quantities. The metal parts are then inserted into the tools by hand.