A ballistic assessment of eye protector lens materials.

The impact resistance of commonly used eye protector lens materials is measured with a ballistic system, using YA inch (6.3 mm.) and Vs inch (3.2 vim.) steel balls. The results, taken in conjunction with the findings of earlier drop-tower work, permit a comprehensive evaluation of the impact resistance of 3 mm. and 2 mm. thicknesses of allyl resin and thermally toughened glass against a series of steel balls ranging in size from 1Y& inches (28.6 mm.) to Vis inch (3.2 mm.). While 3 mm. toughened glass is stronger than 3 mm. allyl resin when impacted by the larger missiles, the position is reversed when the smaller missiles are used. This is held to postulate the need for both drop-tower and ballistic tests in acceptance requirements. Additionally, the relative inferiority of 2 mm. toughened glass at all points of the scale is shown.