Zipper Delamination (Zipper Tearing Off)

Sometimes, when a customer pulls the zipper to open a bag, the zipper stays closed, but the film rips away from the zipper base. This is a heat-sealing issue. The heat seal bar that attaches the zipper to the bag didn't get hot enough or apply enough pressure to fuse the materials, or the materials (eg, PE zipper vs. PP inner layer) aren't compatible.