Purpose of the test
Bending stiffness is of critical importance in the further processing of paper and cardboard. To enable reliable, trouble-free operation of packaging and filling machines, the paper or board must be flexible within defined limits. At paper feed changeover, uniform stiffness properties are also essential for smooth operation of the packaging machine.
ZwickRoell's 2-point flexure test kit covers two applications: measurement of bending stiffness and determination of folding characteristics at a bending angle of 120°. Accurate, high-resolution measuring technology eliminates the need for a change of load cell.
2-Point Flexure Test with ZwickRoell
- Bending forces are recorded by a load cell with a measurement error of just 1%.
- Positioning of the load cell away from moving machine parts avoids signal interference.
- Electronic angle measurement with 0.001° resolution guarantees maximum reliability for measured values.
- Specimens up to 50 or 100 mm wide can be clamped.
- The kit includes precision indexing for gage lengths 1, 2 and 5 mm.
- The kit is available with three different clamping systems: screw clamping, spring clamping and pneumatic clamping.
Buckling resistance of corrugated board to DIN 54608
This 3-point flexure test is performed to determine the buckling resistance of corrugated board to DIN 54608.
The test is used for advanced characterization of multi-wall corrugated products.
Performing the determination is simple and requires only relatively small specimen sizes.
The value depends on various basic parameters:
- SCT of the output paper
- Flute geometry
- Quality of the board adhesion
- Development of material flaws, such as plastic deformation during the manufacturing/molding processes, development of vacuum lines, etc.
4-Point Flexure Test with ZwickRoell
- Using expertise gained from flexure test kits for structural materials, (aerospace, ceramics and high-performance metals), ZwickRoell has developed a 4-point flexure test kit for cardboard and corrugated cardboard.
- Result: a moderately priced fixture which meets all requirements Another important point is that it can even be used with our smallest machine, the zwicki.
- In contrast to instruments that use weights for specimen loading, operation is quick and straightforward. The specimen is simply positioned on the flexure test kit and the test is started. Stiffness is calculated automatically, with allowance for elastic limits.
- The anvils supplied with the flexure test kit are designed to fully accommodate the properties of corrugated cardboard, allowing even warped or buckled specimens to be tested in many cases.
- Measurement is possible even with production-related self-deformation of specimens.
