Solid-Borne Sound Sensor Detects Mold Wear
In injection molds moving parts such as injectors, slides or guide systems above all are subject to considerable wear. For this reason, molds undergo maintenance at regular intervals during production. Fixed maintenance cycles, however, do not take actual mold wear into consideration: short intervals between maintenance interrupt production too often – but if the intervals are too long, there is a risk of producing bad parts.
A newly developed inspection method for injection molds based on the use of solid-borne sound sensors now makes maintenance based on the actual mold condition possible. The solid borne sound sensor measures the sound waves generated in the mold during production. Frequency images for the mold are first recorded when the mold is in perfect condition. As soon as the mold is put into production, a new frequency image is recorded at regular intervals and compared with the mold’s original acoustic "fingerprint". In this way, wear can also be detected while production is running, since the sensor can be attached to the mold at any time for a more or less random analysis. Moreover, it is also possible to attach the sensor to the mold permanently in order to monitor production fully automatically. As soon as a specified limit is exceeded, a warning signal is issued by the system or production is stopped.
Additional applications for the solid-borne sound sensor include detecting breakage of mold cores or determining the optimal balance between cycle time reduction and mold wear. In the future, it may also be possible to detect wear mechanisms on screws in injection molding machines and extruders by means of solid-borne sound sensors.
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