Usage : determines the folding resistance of paper , according to the Louis schopper principle .
Definition : In paper testing, folding endurance is defined as the logarithm (to the base of ten) of the number
of double folds that are required to make a test piece break under standardized conditions:
F = log10 d, where F is the folding endurance and d the number of double folds. Folding endurance is especially
applicable for papers used for maps, bank notes, archival documents, etc.
Standardization : ISO 5626 , TAPPI 423 , ISO 5626
Device Description : the device measures the number of folds until the sample breaks . The tests require that two
samples be tested simultaneously. This is a standard device designed for security papers. It has automatic stop
function after sample break. Standard version for paper up to 0.25 mm thickness , alternatively available for board
. Measurement and display of the folding head temperature optionally available.
Test Description : two samples are clamped in the folding heads for a simultaneous test . the spring supported
samples support are pulled apart, so that samples are clamped at specified force , after pushing the start button
the folding knives begin to guide the sample around the sapphire supported folding rolls , that way samples are
folded at both sides at a radius of about 0.25mm. if one sample breaks the folding of second sample continues ,
until it breaks so . the movement of the folding heads stop after test termination , so that samples can be removed
the device records and displays number of folds until sample breaks.