Posted to News on 20th Dec 2023, 13:30
Contrinex long distance inductive sensors help keep a safe distance
When an automotive sub-supplier needed to verify the presence of a metal washer in a switch assembly, it turned to Contrinex. The 20mm rated operating distance of Contrinex's M18 500 Series inductive sensor was essential in achieving reliable sensing at a safe distance in a congested automated assembly line.
The automotive industry is perhaps the largest employer of automation, using it to provide efficiency and to ensure the accuracy that is an essential part of vehicle reliability.
The automated assembly of the electrical switch needed verification of the presence of a critical dark-coloured wave-shaped washer. The washer, which is used to provide a good mechanical switching action and long-term reliability, is not visible once enclosed within the sealed switch.
The switches are assembled on an automated line because of their small size, and the automotive industry's quality expectation that parts are 100% verified. The assembly operations are intricate with lots of moving parts and there is very limited space to accommodate sensors.
The congested assembly line made it difficult to position a photoelectric sensor, whereas an inductive sensor provided more flexibility on location. Additionally, the uneven surface and dark colour of the wave-shaped washer were a concern for the long-term reliability of photoelectric detection.
The wave washer is inserted early in the assembly of the switch, at the third station of 15. The presence of the washer is checked before the workpiece passes to the next assembly station to guarantee quality and minimise waste should it be missing.
Space within the assembly machinery is very limited, and whilst an inductive offered flexibility in its mounting location compared to a photoelectric sensor, a sensor not larger than M18 was desired. Because of the speed and number of moving parts within the assembly system, it was advantageous to mount the inductive sensor as far from the moving workpiece assembly as possible to avoid collisions.
An M18-sized, Contrinex 500 Series inductive sensor is used because of its long sensing range and its ability to reliably detect the small amount of metal within the wavy washer. The patented Condist technology provides excellent sensing stability against environmental influences, especially temperature change, which provides this non-embeddable M18 sensor with a 20mm sensing distance.
The sensor looks down at the workpiece carriers and semi-assembled switches as they pass below on an automatic conveyor line. If the sensor detects a missing washer, the control system activates a solenoid to prevent the workpiece carrier from advancing to the next station, whilst an alarm is sounded to alert the operator.
Being able to locate the inductive sensor well away from moving parts protects it from collisions and mechanical damage which are frequent causes of downtime. Its excellent reliability ensures end-product quality and eliminates a potential source of customer complaints.
