<p>Fabricated sheet metal parts remain susceptible to formability-related failures that can significantly disrupt operations and result in costly downtime. This paper defines failure in sheet forming as the onset of necking rather than final fracture and presents a practical, measurement-based framework to predict and prevent it. The paper demonstrates why hardness testing alone is inadequate for assessing coil-to-coil formability and advocates comprehensive tensile characterization beyond YTE (yield strength, tensile strength, total elongation) to include uniform elongation, strain-hardening exponent (n-value), plastic anisotropy (r-value), and characterization of elastic modulus behavior during deformation. Forming capability is quantified through Forming Limit Curves (FLCs) and Forming Limit Diagrams (FLDs), supported by grid-based strain mapping with circles/squares and non-contact camera systems. The related Thinning Limit Curve (TLC), derived via constant volume assumptions, enables rapid screening with ultrasonic thickness measurements. Guidance is also provided for robust virtual troubleshooting, and targeted corrective actions are recommended. The combined approach shortens troubleshooting cycles, reduces necking/splitting risk, and improves production reliability across alloys, tempers, and thicknesses.</p>