Safety inspection (Core Project)
These projects are key to ensuring the "safety" characteristics of tempered glass.
Fragment state test
Objective: To test whether the size, shape and quantity of tempered glass fragments meet safety requirements after they break, in order to avoid the formation of large and sharp fragments that could cause serious injuries.
Method: Strike the glass sample with a sharp hammer to break it. Select a 50mm×50mm square in the center area of the fragment and count the number of fragments within the box.
Standard requirement: For glass with a thickness of ≥4mm, the number of fragments should be ≥40. For glass with a thickness ranging from 3mm to 4mm, the number of fragments should be ≥30. A small number of long strip-shaped fragments are allowed, but their length must not exceed 100mm.
Impact resistance test
Objective: To test the strength of tempered glass and see if it can withstand a certain impact force.
Method
1040g steel ball impact: A smooth-surfaced steel ball with a mass of 1040±10g is freely dropped from a height of 1000mm to impact the center of the glass.
2260g steel ball impact: A more rigorous test, with a drop height of 750mm (used for destructive tests, such as pre-treatment for shotgun bag impact tests).
The standard requirement is that when the specimen is damaged, the total mass of the maximum 10 fragments of each specimen shall not exceed the mass equivalent to the area of 65cm² of the specimen.
Impact performance test of shotgun bags
Objective: To simulate the anti-penetration ability of glass when a human body strikes it. This is a high-level test for measuring the safety of glass.
Method: Use a leather bag (impact body) with a metal frame to impact the glass sample, and gradually increase the height (starting from 300mm to 1200mm or even higher).
Standard requirements: After impact, the glass should meet one of the following two requirements:
Undamaged: The glass is not broken.
Safety damage: The glass breaks, but the impact body must not penetrate the sample, and no large pieces of fragments must fall off.
Strength and stress testing
Surface stress measurement
Objective: The strength of tempered glass stems from the compressive stress on its surface. This project directly tests whether the tempering degree meets the standards.
Method: Measure using a surface stress meter.
Standard requirements
Architectural tempered glass: The surface stress should not be less than 90MPa.
Semi-tempered glass: The surface stress is between 24MPa and 69MPa.
Note: Excessively high stress values may also increase the risk of self-explosion.
Curvature measurement
Objective: Tempered glass will undergo a certain degree of bending (bow-shaped deformation) during heat treatment. This project aims to control its flatness.
Method: Place the glass upright and bring a ruler close to the surface of the glass to measure the maximum gap between the glass and the ruler.
The standard requirement is that the degree of bending shall not exceed 0.3%.
Appearance quality inspection
Visual inspection should be conducted at a distance of approximately 600mm from the glass surface under natural light or diffused light.
Chipping: The number of chipping edges allowed per meter of edge length on each piece of glass, with a length not exceeding 10mm, an extension depth from the edge of the glass to the surface of the glass plate not exceeding 2mm, and an extension depth from the plate towards the thickness of the glass not exceeding one-third of the thickness. One place.
Scratches: Minor scratches with a width of less than 0.1mm are allowed. Four scratches with a length of no more than 100mm are permitted per square meter. Scratches with a width greater than 0.1mm are allowed to have one scratch with a length of no more than 100mm per square meter.
Missing corners: Not allowed.
Stones and cracks: Neither is allowed to exist.
There are also corresponding regulations for optical deformation items such as wavy ribs and pockmarks.
