Burst Test

The Zwick Roell burst tester is in the form of a materials testing machine accessory. The testing machine functions as a hydraulic pump and also handles data acquisition and evaluation, providing a program- controlled burst test and ensuring correct results with a minimum of manual intervention. 

When a corrugated board specimen is clamped, it is important to maintain an accurate gripping force to ensure reproducible test results. This operation is simplified by Zwick’s pressure pre-selector, which allows five different controlled gripping pressures to be applied simply by turning the selector knob.  

Particular attention must be paid to the dynamics of the testing instrument when determining the burst strength. As a burst test is performed within a few seconds and the maximum pressure must be determined with absolute precision, the data acquisition rate of the testing instrument must be correspondingly high. If results are to be compared between different laboratories, the data acquisition rate of the instruments must be identical. Variable data acquisition rate enables Zwick Roell instruments to be matched exactly to another instrument, thus avoiding systematic discrepancies between different laboratories. 

Accurate volume flow is also an important factor. Zwick Roell testing machines use digital control to ensure an extremely stable volume flow is maintained during the test, regardless of loading.   

Other features include easy maintenance and the ability to monitor diaphragm condition by performing a ‘dry’ test run. A precise, specified amount of hydraulic fluid is pumped into the test chamber with no specimen present and the maximum pressure recorded, allowing discrepancies in diaphragm behavior to be identified quickly and reliably and recorded against time. 

There are two standards relating to burst tests on paper materials: ISO 2758 describes tests on paper, while ISO 2759 sets out the requirements for carton, corrugated board and corrugated base paper. Zwick has a testing instrument for each of these standards,  covering the entire range from paper to heavy corrugated board.   

Advantages: 

• the operator does not need to worry about details and is free to concentrate directly on the test at hand 
• tests are performed under constant conditions, even when there is a change in operator 
• bursting of the specimen is detected by the machine and the test is ended, reducing stress on the diaphragm and increasing its lifetime 
• variable data acquisition rate guarantees consistent results between producer and processor 
• flow is controlled in a very narrow tolerance range and remains constant even at high loading 
• real-time graphics enable the operator to see immediately if the test has been performed correctly  
• service interfaces and maintenance-friendly design reduce downtime and associated costs.