Can Lid Adhesive Distribution

Can Lid Adhesive Distribution

A qualified can lid must go through stamping, adhesive application, and drying to be completed. The distribution of the adhesive film during application is also very important.

The ideal adhesive film should have a uniform and continuous appearance. The circumferential distribution of the adhesive refers to the distribution of the sealing adhesive along the edge of the cap. For an ideal adhesive film, each quarter (or eighth) of the cap should contain an equal volume of dry adhesive. However, achieving precise 2 or 3 circles of adhesive is difficult. Therefore, the best approach is to have a slight overlap in one of the quarters (or eighths), resulting in 2.1 or 3.1 circles of adhesive application.

There should be no insufficient overlap, and the overlapping area should not exceed one-eighth of a circle. The weight of the overlapping area (quarter) should not exceed 25% of the average adhesive amount of the other three quarters.

Key factors for controlling overlap include the number of adhesive circles available on the applicator head, the delay of the plunger opening sensor, the opening time or dwell time of the plunger, the height setting of the plunger, and the proper matching position of the cap on the head. Incorrect settings and matching positions can lead to insufficient or excessive overlap. The applicator must rotate at least three circles in the high position to ensure that each cap retains an adequate amount of back rotation after adhesive application. This requires a gear ratio of at least 6.01.