Physical Location
Physical identification pinpoints the exact layer or interface where a material or bond has ruptured during stress. Determining the locus of failure allows a technician to understand if a bond failed because of the adhesive or the substrate. In a laminated paperboard, this might be within the paper itself or at the glue line.
This observation is the first step in troubleshooting any structural collapse.
Failure Mode
Adhesive failure occurs when the glue pulls away cleanly from the surface and leaves no residue behind. Cohesive failure happens when the break occurs entirely within the glue layer or entirely within the paper fibres. If the paper fibres tear away, it indicates that the bond strength was higher than the internal strength of the paperboard.
This distinction helps the converter decide whether to change the adhesive formulation or the paper grade.
Performance Root
Microscopic examination is sometimes required to see which specific coating layer gave way. In complex multi-layer structures, the locus of failure can move from one interface to another depending on the speed of the test. High-speed stresses often cause brittle failures that look different from the slow peeling seen in a laboratory.
Identifying where the break started prevents the waste of time spent fixing the wrong component.
