THE universal tensile tester zwicki from Zwick is a suitable instrument testing hypodermic needles.
Available from Australian Testing Solutions , Zwick offers tools to hold the foil as well as adaptors for needle fixing.
Zwick testXpert master test configuration software is a powerful instrument for bending tests on hypodermic needles.
If a dwell time at the end of the bending test is required, a hysteresis test parameter set can be used. This programme is also suitable for the coupling test between needle socket and needle tube.
The testXpert master test configuration is also used for the penetration test. Tolerance curves can be shown on the screen, so that the operator has a 100% control about the relevant curve parameters. The decision "good - not good" can be easily made without operator errors.
As test results all typical occurring force maxima and the friction as mean value can be calculated.
If further curve evaluations (EXCEL-spreadsheets) or data transfer to QC databases are required, testXpert is well prepared for these features.
The bending test (DIN 13097 only) makes sure that the needle is sufficiently elastic and that no permanent deformation occurs during its use.
For this three-point bending test the needle is loaded up to defined maximum forces. It makes sure, that after load removal and a two minute dwell time no permanent deformation can be measured.
The support span of the bend test unit and the maximum load are dependent on the needle’s diameter.
There is no specification concerning the radius of the supports and the bending die. A radius of 2mm seems to be sufficient. Test speed is 5mm/min.
During the test a hypodermic needle penetrates a plastic foil, which has similar characteristics as a human skin, at constant speed.
Simultaneously a curve "force versus time" is recorded and evaluated according to some specific criteria. So, the quality of a hypodermic needle can be weighted and determined.