Overview:

The Magnet Bonding system bonds two rare-earth magnest to a stainless steel substrate. Before bonding the two magnets, the system applys a cyanoacrylate adhesive to the substrate, and inspects the adhesive for coverage using machine vision.

Process Description:

Processing begins with the arrival of an assembly pallet, with the target assembly passively fixtured on the pallet.  The system aligns and clamps the pallet, locates the target with the machine vision system, and applies two parallel smears of cyanoacrylate adhesive to the target.

When the adhesive is applied, the arm-mounted machine vision is used a second time to verify the adhesive. The adhesive smears are measured against present parameters for centroid location and overall size. If the adhesive placement meets specification, two rare-earth magnets are acquired from a custom vertical tube feeder, and placed onto the target substrate.

The finished assembly pallet is then released to the next system downstream for processing, and a new pallet is loaded into the system.

Technical Challenge:

During development it was discovered that speed affected the accuracy of the magnet placement.  At first this was considered to be an issue with the settling time of the robot, and that the robot position was not actually stable when the magnets were placed.  However, further tests showed that the phenomenon disappeared if the adhesive were not in use.  No never confirmed, it was thought that the fluid pressure,, created by squishing the magnet into the adhesive, was causing the magnet to "surf" on the adhesive and move out of position.  The problem was corrected by slowing to a reduced speed when the magnet was positioned a millimeter above the target surface, and then holding the magnet for a small dwell period after placement.