Drop Ball Test for Sunglasses

Sunglasses are one of the most common products today, available in a wide variety of styles and colors, including popular Acetate Sunglasses, Metal Sunglasses, Titanium Sunglasses, and those made from natural materials like horn and wood. With diverse designs and rich colors, consumers have many options to choose from. Sunglasses not only enhance your appearance but also protect your eyes from harmful UV rays. However, an important quality indicator is the drop ball test.

Impact Resistance Testing for Sunglass Lenses

The drop ball test primarily focuses on the lenses of sunglasses. As we know, the lenses are one of the most critical components, and in addition to providing UV protection, their impact resistance is vital. This ensures that your eyes are not injured by broken lens fragments in the event of an accidental fall.

Recently, I came across a news story about a woman wearing glasses who accidentally fell and her glasses hit a protruding rock. The shattered lens caused serious injury to her eye, which looked extremely dangerous. Fortunately, timely medical attention helped her recover. According to the doctor, if the lens fragments had pierced her eye even slightly deeper, her vision could have been permanently damaged. As someone who wears glasses, this story resonated deeply with me, highlighting the importance of lens impact resistance. I wondered if her lenses met the necessary impact resistance standards. This article aims to explain the lens drop ball test.

The FDA requires that sunglasses imported into the U.S. comply with the impact resistance testing standards outlined in 21CFR801.410, also known as the drop ball test. What is the drop ball test? It involves dropping a steel ball from a specific height onto the convex surface of the lens and observing whether the lens shatters. The FDA uses this test to assess lens impact resistance. During testing, a fixture is used to hold the frame in place.

The steel ball must have a diameter of 0.625 inches and weigh approximately 1 ounce, dropped from a height of 50 inches. The lens must not break upon impact.

When lenses or sunglasses are exported to the U.S., they must pass the drop ball test, also known as the bead drop test, in accordance with standard 21 CFR801.410. The steel ball used for the impact testing verifies that the batch of products meets the required impact resistance standards for export to the U.S. When exporting goods to the U.S., it is essential to provide not only the FDA manufacturer and product registration numbers but also the following quality inspection documents:

• Certification Statement of Impact Resistance: This document certifies that the manufacturer has conducted impact resistance testing (drop ball testing) in accordance with FDA regulations and has passed the test. It must be signed by an authorized representative of the manufacturer.

• Impact Resistance Test Report: Also known as the drop ball test report, this document serves as the basic trial for final batch testing of all related lenses to confirm compliance with impact resistance standards for export. This report is generally provided only if specifically required by customs; usually, the certification statement suffices as proof of compliance.

   

Sunglasses are a primary product in our factory, including acetate, metal, and titanium sunglasses. While we do not manufacture the lenses ourselves, we pay great attention to the qualifications of the lens suppliers. They typically pass rigorous testing before the lenses are shipped. Upon receiving the lenses, we also conduct thorough inspections, including visual checks and functional tests, which encompass the drop ball test.