Crease and stiffness testers are useful to test carton board, paper, printing and packaging materials. These are important measures to have correct and uniform quality. The board stiffness and crease recovery is critical in the performance of cartons. Especially on high speed packaging machines. And when manually folding. The value of crease stiffness is technically important in the folding of carton blanks. Most importantly during their release and closure.
The crease recovery (spring back) can result in forces, which distort the erected carton or cause stresses to closures. Thereby, reduce their effectiveness.
Crease recovery is the decrease in resistance by the creased board after it is folded 90°. This is at the crease measuring the recovery force after 15 secs. Bending a 50mm length of board through a 15° angle determines board Stiffness.
The Crease and Stiffness testers optionally can test round corner creases. This is using easily changeable Round Corner Jaw.
The Crease and Stiffness Tester Series:
Standard Model (C0039-M1) 
The Model C0039 (M1) can determine the crease recovery by the decrease in resistance offered by creased board after it is folded 90° at the crease measuring the recovery force after 15 secs. Board Stiffness is determined by bending a 50mm length of board through a 15° angle.
Round 90° Crease Stiffness Tester (C0039-M2) 
The C0039-M2 offers the same capabilities as the C0039, with the added functionality of being able to test for round corner creases. Round corners can be tested with ease using the easily changeable Round Corner Jaw. Folds are still able to be bent at 90°, and the Round Corner Jaw allows leeway for rounded corners to bend as intended. Another added functionality of the C0039-M2 is the ability to adjust the Load Bar position via the Load Bar Adjustment Knob, allowing for a range of different test lengths of 5mm, 10mm or 15mm creases.
Digital Crease Stiffness Tester (C0039 - M3) 
Along with the above-mentioned features of the C0039 M1 & M2 model, C0039-M3 includes a digital display. The real-time display screen is the latest addition to the Digital Stiffness Tester. The digital display is colour touch screen ensures simple operation making it convenient to check statistics, test reports and results. This product is the latest and most updated version available.
Crease and Stiffness Sample Cutter (C0016)
IDM’s sample cutter is designed to assist in the easy and accurate cutting of sample specimens for both crease stiffness and bending stiffness testing.
Test Samples are of the following sizes:
• Crease stiffness testing 38 x 36mm
• Board samples 70 x 38mm
Optional Items:
Test Software 
The IDM Crease and stiffness tester can be purchased with standard RS232 and software to automatically capture the output of results to a PC where stiffness/crease ratios can be calculated, test results saved, and test reports created and printed. This makes the CST even more easy to use with accurate precision results.
Carton Crease proofer 
Used to determine the type of crease after bending samples.