A valid recipe becomes incorrect when it is applied to a different polymer, grade, thickness, color, surface, tool revision, or machine configuration. Similar-looking sheets can have different absorption, melt strength, shrinkage, moisture sensitivity, and release behavior.
Material identity, lot, thickness, extrusion direction, masking, tool revision, and recipe version should be verified before troubleshooting begins. A sudden broad failure after a changeover is more likely a configuration mismatch than simultaneous mechanical faults.
Recipe selection should use controlled naming, revision history, access permissions, and machine or tool checks where available. Operators should not correct a wrong recipe by making undocumented live adjustments. The material and process record must stay linked to the produced parts.