Posted to News on 9th Apr 2024, 15:00
Reliable checking for the presence of small metal inserts
When a supplier of injection moulded parts for the automotive industry needed a reliable method of checking that threaded inserts had been correctly mounted, it turned to inductive sensors from Contrinex.
To enable the fast screw assembly required by automotive plants it is common to embed threaded inserts, typically made of brass, into plastic mouldings.
These nut-like elements are crucial to ensuring the correct final assembly process of the car and so the supplier must be able to ensure they are all present. It is not uncommon for automotive companies to return several days worth of production parts to a supplier and levy substantial fines if even a minor error is found.
The design of the moulded plastic parts used in automotive air filtration systems is problematic because it prevents visual checking of the presence of the inserts so a reliable test mechanism had to be found.
Contrinex DW-AS-513-M30-002 Extra Distance inductives are used in a checking fixture to detect if any inserts are missing or incorrectly mounted. The solution exploits the unique sensing capabilities of the Condist technology in these 500 Series sensors, utilising their longer sensing distances, 40mm for this sensor, and their better stability to environmental influences like temperature changes. The long operating distance and high sensing stability enable the detection of small inserts through a thick layer of plastic.
The test fixture is designed to accept a finished moulding and is equipped with sensors at each of the insert locations. Each sensor can detect the presence of the corresponding metal insert through moulded plastic and so confirm compliance with the specifications. The sensors PNP Normally Open output provides a logical GO NO GO feed to a microcontroller.
