4-Point Flexure Test

One of the elements required when using the McKee formula to predict box crush resistance is that of flexural strength. The 4-point flexure test delivers reliable stiffness values in the machine direction and perpendicular to it. This is particularly important for mini-flute corrugated board, where stiffness plays a significantly greater role than with standard flute heights.

Using expertise gained from flexure test kits for structural materials, (aerospace, ceramics and high-performance metals), Zwick has developed a 4-point flexure test kit for card and corrugated board. The result is a moderately priced fixture which is comparable to  existing solutions and can be used on our smallest machine, the zwicki-Line.

In contrast to instruments which use dead-weights for specimen loading, operation is quick and straightforward: the specimen is simply placed on the flexure test kit and the test is started. Stiffness is calculated automatically, with due regard for elastic limits.

 Anvils with all-round movement enable even buckled or warped specimens to be tested in many cases.

Tests are performed to ISO 5628. 

Advantages: 

• test takes less than 60 seconds 
• test graph allows fast plausibility check during the test 
• flexure test kit anvils are optimized for card and corrugated board properties
• measurement is possible even with production-related self-deformation of specimens
• test is performed reliably within the elastic limit.