ASTM B571 Test Fixtures & Test Systems Model: G-ASTM-B571-N11

The Mechanics of Interfacial Separation: ASTM B571 Method 11 is the primary qualitative assessment for the bond strength of ductile metallic foils and electroplated layers. Unlike quantitative peel tests that measure Newtons per millimeter, this method is a Pass/Fail evaluation of the interface’s resistance to stripping. The mechanical challenge lies in the MTO G50 Universal Peel System’s ability to maintain a consistent pull-axis. To initiate the test, a portion of the coating is separated from the substrate—often using a sharp blade—to create a lead tab. This tab is then gripped and pulled at an angle of 90° or 180°. From an engineering perspective, the Rate of Separation is the critical variable. If the pull is too rapid, the inertia can cause a clean break of the coating itself rather than a test of the bond. Conversely, a slow, steady pull allows the stress to concentrate at the leading edge of the peel. If any portion of the substrate is pulled away with the coating (cohesive failure of the base metal) or if the coating stretches significantly without lifting, the adhesion is considered superior. However, if the coating zips off with zero resistance, the plating bath chemistry or the pre-treatment cleaning cycle is likely contaminated, as the mechanical interlock at the atomic level has failed to form.