The Coesfeld Intrinsic Strength Analyzer automatically evaluates the minimum tearing energy T0 that initiates and drives crack growth. Measuring the endurance limit with classic methods can take months. The ISA based on Endurica testing and evaluation methods generates results within less than 8 hours. The measurement runs fully automatic. Critical Tearing Energy Tc can be estimated as a side product at the end of the measurement. The ISA is a cutting force measurement following fully PC controlled measuring protocol.