Tempered glass tables are popular and commonly seen in home decor, and many wonders if it is fragile. 

A tempered glass table is not easily broken due to the great strength of tempered glass. Tempered glass is 3-4 times stronger than annealed glass and has a minimum surface compression of 10,000 psi or greater. Generally, it breaks at around 24,000 psi, while annealed glass is 6,000 psi.

Continue reading by looking at the data gathered to show how hard it is to break a piece of tempered glass, its toughness will exceed your imagination.

Is tempered glass table fragile?

Sometimes, we might drop something on the glass tabletop accidentally, what will be happened?

Futureglass gave the answer. He tests tempered glass table tops’ durability and impact resistance by dropping different objects in a series of videos. The data is really surprising. Check it out below:

Conclusion: Tempered glass table in daily use is safe, has strong durability, and is not easy to break. A normal object falling will not shatter the glass table top.

Note: These test breakage results are relevant to the tempered glass’s thickness, the drop’s height, dropping speed, weight, even if the object is sharp, etc. NEVER take a test in unsafe situations

Is tempered glass impact resistant?

Considering that normal objects won’t break it, what about more severe impacts occurring? Will the tempered glass still hold up？

Car wars make a tempered glass test, walking and bouncing on it, using a skateboard and dirt bike drive on it. Get the full test in this video:

Conclusion: Tempered glass passed most tough tests, which were not broken under severe impact, and showed incredible toughness and flexibility. 

Note: The length, width, and thickness are closely related to the tempered glass’ loading capacity. Moreover, the distance, location, and method of glass support points will also affect the load-bearing capacity of the glass.

Is tempered glass falling-resistant?

Although tempered glass is impact resistant, it is not completely unbreakable. We all know that glass will shatter when dropped, but from how high will it shatter? 

Greg Salazar made a test that dropped a piece of P400S tempered glass at different heights, horizontally and vertically, to check the tempered glass’s impact. It could help us to get some ideas about that. And here is the test video:

Conclusion: Tempered glass only damaged a little bit on the edge (the weakest part) when falling at approximately 3 feet high down and cracked at approximately 7 feet high.

Note: The testing ground directly influences the test; even if the same piece of tempered glass fell on the hard ground/stones road / soft mat, these results might vary.

ANSI Z 97.1 Impact Test of tempered glass

As a furniture supplier, sometimes we get questions from the client, like, Is there some authoritative data to show that tempered glass is impact resistant?

The answer is YES! Fully tempered glass as a type of safety glass requires to pass impact testing of EN 12600 or ANSI Z 97.1

The following video sets the ANSI impact force to 400 ft. Ibs （According to Consumer Product Safety Commission, Category 2） to test the performance of different types of glass in the impact.

 Test results:

Group 1

● Unfilmed Ceramic—- failed.

● Unfilmed Wired Glass—failed.

● Annealed glass —failed.

These three types of glass break completely after impact,  incapable of stopping the impact. Their glass shatters into very sharp chunks, which can easily cause serious injury. And the Unfilmed Wired Glass even exposes embedded wires that can pinch limbs and cause further injury.

Group 2

● Filmed Wired Glass—Pass

● Filmed Ceramic—Pass

● Laminated Ceramic—Pass

Although all three varieties of glass are damaged to varying degrees, but they all pass the CPSC (Consumer Product Safety Commission) impact safety test. While broken, there is no penetrating breakage.

Filmed Wired Glass and Filmed Ceramic withstood the impact and held the broken glass fragments together. However, it is important to note that replace the damaged glass as soon as it breaks.

Group 3

● 1/4″ Tempered Glass

● 3/4 Tempered Glass （1/4 Tempered +fire resistive interlayer + 1/4 Tempered）

Conclusion: Tempered glass passed the ANSI Z 97.1 Impact test and remained intact under the first impact. Its harmless fragments also show the safety character, which will not hurt people when shattering.

How much force does it take to break tempered glass?

While tempered glass is extremely durable and can sustain impacts, it is not unbreakable. The tempered glass will break if the force stress reaches the strength per unit cross-sectional area. 

According to the ASTM C1048 standard for the glass industry, the minimum surface compression of tempered glass is 69 MPa (10,000 psi) per square inch, and the minimum edge compression is 67 MPa (9,700 psi). In general, the tempered glass breaks at a surface compression pressure of approximately 24,000 psi.

 Joseph Weeks (Engineer) at http://www.madsci.org/ uses physical stereoscopic engineering examples to explain how much force is required to break glass for different objects. 

For example, if a screwdriver with a tip size of 0.25″ x 0.01 is applied to glass, the force required to exceed 24,000 psi of glass strength is 60 pounds of force (24,000 psi * 0.00 25 sq. in.); if the glass is applied by hand (roughly 25 sq. in.), it needs at least 600,000 pounds of force (24,000 psi * 25 sq. in.) to break the glass.

The sharper the object used to break the glass, the smaller its impact on the glass area, the more focused the force, and the easier it is to break the glass. The larger the area of the object in touch with the glass, the more force will be dispersed in a larger area of the glass, it takes more force than a sharp metal object to break the glass.

Source:

https://www.wikihow.com/Temper-Glass

https://www.youtube.com/channel/UC94o0Ukng8XjKEWFIJEOg2g/videos

http://www.madsci.org/posts/archives/2006-11/1163779223.Ph.r.html