FNCT is short for full notch creep testing, allowing evaluation of the resistance of a plastic material to stress cracking

FNCT - testing

FNCT – full notch creep testing

The full notch creep test (FNCT) according ISO 16770 is rapidly becoming the preferred way of measuring the stress crack resistance of a polyethylene.

A constant stress is applied to the specimen, most conveniently via a lever arm loading arrangement, and the time for the specimen to fail is recorded. The specimens are generally tested at elevated temperature in a test fluid, which is often a detergent solution to accelerate cracking. The stress level applied to the specimen depends upon the stress crack resistance of the material and the test temperature.

The aim of FNCT is to assess resistance to brittle failure and the schematic diagram above shows the fracture surface that is sought. In order to achieve brittle failure at any given temperature, the applied stress levels must be significantly lower than the corresponding yield stress at that temperature.

FNCT equipment

impact have designed their own bespoke FNCT test equipment in order to give highly accurate results.  Our equipment design was that used in the original FNCT standard (ISO 16770) as can be seen in the diagram.

We have 24 FNCT stations available for rent and can handle a range of temperatures.  The testing can be performed with a wide range of chemical agents in order to simulate stress cracking.

practical uses for FNCT

Practical uses of FNCT


impact perform FNCT for a wide range of clients, including pipe specification and material analysis, containers and automotive.