Inside the Fold: Why the Hinge Is the Hardest Problem in Mobile Engineering

When Samsung handed out review units of the original Galaxy Fold in April 2019, it took journalists at The Verge, Bloomberg, and CNBC only about two days to break them. Screens bulged at the crease, flickered, lost pixels near the hinge, or died completely. Samsung delayed the launch by months, later tracing the failures to debris getting past the hinge and to a protective polymer layer that reviewers mistook for a removable screen protector and peeled off. It was an expensive, public lesson in just how hard it is to make a phone that folds.

Seven years and several device generations later, foldables have gone from a cautionary tale to a real product category — and in markets like the UAE, a genuinely popular one. But the core engineering problem Samsung ran into in 2019 was never fully solved. It was managed.

The Problem Nobody Talks About: It's Not the Screen

Most coverage of foldable durability focuses on the display, but the harder problem sits underneath it: a mechanical hinge that has to let a rigid-feeling slab of electronics bend thousands of times a day without crushing the delicate OLED panel folded over it, without letting dust and sand in, and without developing a visible crease that ruins the illusion of a normal screen.

That's three competing goals pulling in different directions. A hinge loose enough to fold smoothly tends to let debris in. A hinge sealed tightly enough to keep debris out tends to add friction that stresses the display at the fold point. And a hinge designed to minimize the crease — usually by using a tighter folding radius — puts more mechanical strain on the panel than a looser, more gradual fold would.

Samsung's answer, refined across five generations of the Galaxy Z Fold, is a multi-bar hinge: instead of a single pivot, several small interlocking plates move in sequence, letting the display rest on a shallow U-shape rather than folding sharply in half. Competing approaches, like Huawei's and Honor's water-drop hinges, chase the same goal with a different geometry, aiming for an even gentler curve so the display barely bends at all at its tightest point.

Glass That Isn't Really Glass

The other half of the story is the cover layer sitting on top of the display. The original Galaxy Fold shipped with a polyimide (a flexible plastic) cover because true foldable glass wasn't ready for mass production — the plastic scratched easily and was the layer reviewers damaged by peeling it off.

By the 2020 Galaxy Z Fold2, Samsung Display had moved to what it calls Ultra Thin Glass (UTG): actual glass, but thinned down to roughly 30 microns — about a third the thickness of a human hair — and laminated with a polymer coating so it can flex without shattering. It's a genuine materials-science achievement, but it comes with a trade-off: independent hardness testing after the Fold2's launch found the UTG panel scored only around a 2 on the Mohs scale, no harder than the plastic it replaced, because the ultra-thin glass still needs a soft, scratch-prone protective coating on top to keep it flexible.

Manufacturers now publish fold-cycle ratings as their main durability pitch: Samsung rates recent Galaxy Z Fold hinges for around 200,000 open-close cycles, which it estimates covers roughly five years of typical use. Motorola and Honor have claimed higher figures — 400,000 and 500,000 cycles respectively — for their Razr and Magic V lines, though those numbers come from manufacturer lab testing under controlled conditions rather than independent verification. Third-party stress tests have found wide variation between models, which is a reminder that a lab rating describes a best case, not a guarantee.

Why the UAE Keeps Buying In

Nowhere has embraced foldables faster than the Gulf. When Samsung launched the Galaxy Z Fold3 in 2021, Samsung Gulf Electronics reported UAE pre-orders running roughly eight times higher than the previous generation — and in December 2025, Samsung's limited-edition Galaxy Z TriFold, priced at Dh11,999, reportedly sold out in the UAE within minutes of going on sale, according to regional tech coverage. Khaleej Times also reported that the Galaxy Z Fold8 helped Samsung set an all-time global sales record this year, though the outlet noted Samsung hasn't broken out UAE-specific figures for that launch.

The pattern fits a broader trend Gulf News has tracked for years: the UAE tends to be a first-stop market for premium, high-price-point devices, with early adopters willing to pay a premium for something genuinely new rather than wait for the technology to mature elsewhere.

The Fold Is Still a Compromise

None of this means the engineering problem is solved — it means manufacturers have gotten better at hiding the compromises. Every foldable on the market today is still a negotiation between crease visibility, dust resistance, display hardness, and hinge longevity, and improving one almost always costs something on another axis. The crease is less visible than it was in 2019, hinges last longer, and glass has mostly replaced plastic — but scratch resistance is still worse than a normal phone screen, and real-world longevity still depends heavily on how carefully an owner treats the fold line.

For now, that's the deal foldable buyers are making, whether in Seoul, London, or Dubai: a phone that can become a tablet, in exchange for a screen that will always be a little more fragile than the one it replaced.