ISO 2758 Burst test for paper | ISO 2759 Burst test for cardboard
ISO 2758 defines a method for determining the burst strength of paper, whereby the specimen is exposed to increasing hydraulic pressure. It can be used on paper with burst strengths ranging from 70 kPa to 1,400 kPa. It is not suitable for individual components (such as paper used for the corrugated and non-corrugated layers of corrugated board) of multi-layer cardboard. In this case, method ISO 2759 is more suitable.
Standard ISO 2759 defines the method for determining the burst strength of cardboard (including corrugated board and solid board) that lies within the burst strength range of 350 kPa to 5,500 kPa.
ZwickRoell offers burst testers for determining the burst strength in accordance with standards ISO 2758 and ISO 2759 for paper to heavy corrugated board.
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Burst test according to ISO 2758 & ISO 2759 explained
In the burst test according to ISO 2758 and ISO 2759, a specimen is placed over a circular, elastic membrane, which is firmly clamped around the edge, so that it can bulge freely together with this membrane. A constant flow rate of hydraulic liquid is used to bulge the membrane until the sample bursts.
The maximum hydraulic pressure applied in kPa is the burst strength. The burst index is calculated by dividing the burst strength of the paper/cardboard in kPa by the mass per unit area, which is determined in accordance with ISO 536.
- To measure the burst strength, the specimen is firmly clamped between two clamping rings. Maintaining the gripping force when gripping the specimen is an essential for producing reproducible test results.
- Particular attention must be paid to the dynamics of the testing equipment. As a burst test is performed within a few seconds and the maximum pressure must be determined with absolute precision, the measurement speed of the testing instruments must be correspondingly high.
- If results are to be compared between different laboratories, the measurement speeds of the instruments must be identical. A constant volume flow must also be maintained during the test with a high degree of accuracy.
Burst tester for testing to ISO 2758 and ISO 2759
ZwickRoell test device for determining the burst strength to ISO 2758 and ISO 2759:
- The test device for burst testing consists of a hydraulic actuator and a burst device.
- The hydraulic actuator is used to generate pressure. It is mounted in the testing system. The volume flow can be steplessly adjusted by changing the crosshead speed. The hydraulic actuator is connected to the burst device via a high pressure hose. Pressure is measured electronically using a strain gauge sensor.
- A pneumatic actuator is integrated in the burst device. It is used to clamp the specimen between the compression platen and the pressure chamber. The moving crosshead presses against the hydraulic actuator during the test, whereby a volume of liquid is pressed into the pressure chamber. The resulting, increasing pressure causes the rubber membrane to arch. The rubber membrane then presses against the specimen until it breaks.
Advantages:
- Burst tests with ZwickRoell universal testing machines are program-controlled, ensuring correct results at all times with minimal manual operator intervention.
- ZwickRoell offers a pressure pre-selector, which allows rapid selection of up to five different controlled gripping pressures via a rotary switch.
- The machine detects bursting of the specimen and stops immediately. This reduces the load on the diaphragm, extending its life.
- Tests are performed under constant conditions, even when there is a change in operator.
- The flow is controlled within a very narrow tolerance range and remains constant even at high loading.
- ZwickRoell materials testing machines employ digital control to ensure a constant volume flow regardless of load.
- Real-time graphics enable the operator to see immediately if the test has been performed correctly.
- Variable data acquisition rate guarantees consistent results between producer and processor, avoiding systematic discrepancies between different laboratories.
- Service interfaces and maintenance-friendly design reduce downtime and associated costs.
