Exploding panoramic sunroof

Glennmac · « **on:** May 11, 2015, 22:53:27 »

Last Thursday whilst doing 70 mph on the m25 there was Noise like a shot gun going of in the car and most of the front section of my panoramic sun roof shattered on me. The Santa Fe is 6 months old. Nothing hit it and I now read this been on the news in the USA and if type it into google it's endless the amount of times this has happened. It's leased for another 18 months but going legal and finishing my lease.....thank god the kids weren't in the car.

Glenn

dartman · « **Reply #1 on:** May 12, 2015, 08:39:32 »

It's not confined to Hyundai, glass is a liquid and the toughened variety has an outer skin under tension, glass is made from sand which contains impurities such as metals and harder rock particles. When in the glass making process some of these impurities are suspended in the glass, these impurities gradually move and can reach the outer skin. When everything is lined up wrong the glass flexes (it's always flexing otherwise it would break) and the impurity touches the skin and releases the tension leading to the roof shattering, the same thing can happen to toughened windows in doors, keeping the glass at an even temperature and reducing the flexing helps. Seeing as a car is outside and subject to the weather and cars are made lighter so will flex more, then expect more shattering, though there have been reports that Far East made glass is more susceptible due to lower QC in the glass making

Disco J Supernova · « **Reply #2 on:** May 12, 2015, 13:26:41 »

People say that, but it's not a liquid unless you melt it. - It's an amorphous crystalline solid (usually of silica).

I'd agree that the QC of glass varies from place to place and with composition, but Japan is probably the leader at the moment. - NSG is the parent company of Pilkington's and make some pretty clever polychromic glass sunroofs.

Ruperts Trooper · « **Reply #3 on:** May 12, 2015, 13:43:17 »

Glass used in cars has a major disadvantage - it's heavy - so car makers specify the thinnest glass the think they can get away with and since the roof is a stress-bearing panel in most cars it's not difficult to go too far.

dartman · « **Reply #4 on:** May 12, 2015, 16:54:26 »

RT you can bend toughened glass to a remarkable degree, I remember we used to press out a mini screen by sitting in between the front seats and pushing them out with our feet, the centre bent out a good 6" before the side seals let go.

Disco J Supernova · « **Reply #5 on:** May 12, 2015, 18:51:41 »

The windscreen is laminated; a sunroof isn't. - That's why the windscreen will flex and a sunroof shatters.

dartman · « **Reply #6 on:** May 12, 2015, 20:17:45 »

Quote from: PobodY

The windscreen is laminated; a sunroof isn't. - That's why the windscreen will flex and a sunroof shatters.

No these were toughened screens, I'm not talking about the BMW excuse for a mini. You can't flex laminated screens they crack, but not explode

Paul · « **Reply #7 on:** May 23, 2015, 09:44:05 »

I looked in to toughened glass after a 5 foot glass table exploded on me.

It turns out to make a toughened glass you heat the glass to just about melting point, the spray a special liquid on it to cool the surface only.

The center then cools more slowly; this creates stress in the surface of the glass making it hard and under tension.

If the is a small chip or imperfection in the surface of the glass at sometime this will give and the glass will shatter.

The table was standing on edge on my safety shoe and not on the floor at the time!

Disco J Supernova · « **Reply #8 on:** May 23, 2015, 10:12:11 »

It's pretty complex stuff and not all "toughened glass" is the same. - Pilks can make a usable hammer out of theirs... but they're probably not supplying Hyundai.

I know they make the glass for Mercedes sunroofs because they also made it photochromic. - I was discussing it with them a month or so ago.

SNAKEBITE · « **Reply #9 on:** June 22, 2015, 16:52:22 »

Quote from: PobodY

The windscreen is laminated; a sunroof isn't. - That's why the windscreen will flex and a sunroof shatters.

So am I missing the point if I wonder why they don't laminate the sunroof?

Ruperts Trooper · « **Reply #10 on:** June 22, 2015, 18:19:43 »

Quote from: SNAKEBITE

Quote from: PobodY
The windscreen is laminated; a sunroof isn't. - That's why the windscreen will flex and a sunroof shatters.

So am I missing the point if I wonder why they don't laminate the sunroof?

Weight and cost.

dartman · « **Reply #11 on:** June 22, 2015, 20:03:33 »

Quote from: Ruperts Trooper

Quote from: SNAKEBITE
Quote from: PobodY
The windscreen is laminated; a sunroof isn't. - That's why the windscreen will flex and a sunroof shatters.

So am I missing the point if I wonder why they don't laminate the sunroof?

Weight and cost.

Cost maybe, but weight could be reduced with laminated and stronger.

SNAKEBITE · « **Reply #12 on:** June 23, 2015, 13:05:42 »

What about it being safer?

dartman · « **Reply #13 on:** June 23, 2015, 16:17:15 »

Quote from: SNAKEBITE

What about it being safer?

Depends how big your are, they are not easy to fall out of, always wear a seat belt

Geoffrey Gellyneck · « **Reply #14 on:** June 23, 2015, 16:52:12 »

A couple of months back our SF rear screen "exploded" over my head!
Opened the tailgate to get some stuff out the back, couple of bags removed and bang! A hole about the diameter of a football in it. Looked around, nothing on ground or in car.
Guy fitting replacement said it's not that uncommon on all marques.