NBS Crumpling device

NBS Crumpling device

The NBS Crumpling device is mainly used for banknote testing. It consists of a fork for rolling up the paper sample and a tube in which the rolled sample is crumpled under a fixed force.

Automated pressuring device (optional)

The NBS Automated Pressuring Device (article no. 422.250) removes variation in the applied force. Its driving unit always pushes the plunger down with the same force of 100 N for a fixed period of time. This prevents the crumpled sample from being compressed further than intended and gives more reproducible test results. All versions of the NBS crumpling device fit on this unit, so it can also be ordered for existing devices.

General

The crumpling test simulates the extreme handling that banknotes undergo in circulation. It can be performed on wet or dry, printed or unprinted samples. Crumpling disturbs the interlaced fibres and loosens the bonds, so the structure becomes less compact, weaker and more permeable to air.

The effect of crumpling is measured by the change in air permeability (porosity), water absorption and/or tensile strength. These properties are measured before and after crumpling, on the same or an identical sample.

Method of operation

1. Roll up the (banknote) paper sample with the fork.
2. Insert the rolled sample into the tube.
3. Apply force to crumple the sample.
4. Measure the properties of the crumpled sample and compare them with the values before crumpling.

Standards

The test is based on the method developed by the US National Bureau of Standards (NBS, now NIST).