In order to test the durability and resilience of sunglasses or reading glasses, the mechanical properties of the glasses are tested alongside the optical properties.
Glasses endurance test
With this test, the durability of the hinges is tested. During the test, the glasses are clamped in a device and the hinges are put under strain from a variety of different angles. After 500 cycles, the hinges should not be “worn out” or overstretched and must still be fully functional.
This test checks to see whether the sunglasses or reading glasses have the strength required by the standards. The glasses are stretched out on a retention device and pressure is placed on the lenses. After the test is ended, the frames should not have deviated from their original form by more than 2 %. They should also not break and the lenses should not fall out of the frames.
In the so-called “ball drop test” a 16 g steel ball is dropped onto the lenses from a height of 1.27 m. The lenses should not break, splinter or fall out of the frames upon impact.
Further mechanical test
- Flammability test
- Perspiration resistance test
- UV irradiation of the lense