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Mobiles get the crash test

Phones are always being dropped, squashed and prodded. So how on earth do they survive? Simon Usborne visits the lab where they're put through their paces

Tied down with metal clamps on steel benches, ranks of mobile phones are being technologically tortured. If they could cry out, they would – but nobody would hear, because the noise of a hundred steel pistons pummelling their fascias is so loud that people rarely visit this windowless room for more than a few minutes at a time. And, anyway, the walls are soundproofed. "This is what I do," Kevin Smith shouts over the din. "I break mobile phones."

He might sound like a neo-Luddite hell-bent on destroying weapons of mass communication, but Smith works for the world's biggest mobile-phone manufacturer. As head of "reliability" at Nokia, which employs more than 120,000 people worldwide and made 468 million phones last year (more than a third of the world's mobiles), Smith and his team are part of a global league of engineers and white-coated technicians who make sure they scratch, scuff, crack and snap their phones so we don't have to.

The pneumatic pistons are being used at the laboratories near Farnborough in Surrey to test the buttons, rockers, sliders and D-pads (directional pads) on Nokia's new phones. One handset lies face down while a pneumatic arm opens and closes its "camera reveal" – the slidy bit that covers the lens – over and over again. "Tut-pshhh, tut-pshhh, tut-pshhh", the little piston fires several times a second.

This is just a small part of the testing Nokia's devices undergo. There's a good reason why Smith goes to such lengths to make sure his handsets are robust; mobile phones are probably the most abused gadgets we have. "Modern mobile phones have removable memory, a hard disk, a display, a keyboard, a microprocessor – they're the same as laptops," Smith says. "But would you drop a laptop? Would you chuck it on to your desk, or shove it into your jeans and sit on it or throw it into your handbag? Drop a laptop and you expect it to break. But there's a perception that you can drop your phone and expect it to work."

The 15-stone man

We've all done it; you put your phone in your back pocket – and then sit on it. That's why Smith subjects all the phones to the "three-point bend". It's pretty simple – the phone is clamped at each end while a metal bar is brought down on its middle. "It applies the same force as if it were a 15-stone man sitting on a hard chair," Smith says. As the pressure builds, the phone creaks and bends, but it springs back as soon as the bar is lifted.

If the reliability team spot any problems after the bend test – or any test – they talk to the phone's designers. "It's a very important relationship," Smith says. And the process starts long before the soldering irons are even warmed up; the designers will send computer-generated plans, which Smith and his team pore over in search of potential glitches.

The button presser

To make sure Nokia's buttons withstand years of pushing, Smith and his crew subject handsets to weeks of punishment. A metal arm positioned above the keypad of an N79 phone is firing five rubber-tipped rods at the controller. Together, they resemble a crazed team of pigeons trying to peck at imaginary worms inside the phones. The assault will go on, non-stop, for two weeks, and each button will be pressed a million times. Touch screens get the same treatment. "We divide the screen into segments and press each one a million times," Smith says. "And we do it just as hard as we would if they were buttons."

Smith's job is to predict every which way the "end user" will treat a phone, but sometimes they miss something. "We had feedback from Japan that a particular phone had a loud click when you pressed the buttons," Smith says. "It was seen as very disrespectful when people were texting on public transport so, for that market, we reduced button noise."

The weather test

This month's "snow event" might have tested our transport infrastructure, but for our phones it was nothing more than a cold snap. Nokia's climate room is home to ovens and freezers that subject handsets to temperatures ranging from a toe-blackening minus 40C all the way to a furnace-like 80C (an improbable 176F). "If someone's stuck in Siberia and calls 999, we need to make sure their phone starts," Smith says. "We look at the plastics and make sure there's no warpage or movement."

There's also a drip test designed by one of Smith's crew. Water is pumped into a small tray above the phone. A grid of needles allows water to drip on to the phone and into the paint tray, where a pump sends it back round again. Even if you leave your phone outside in the rain, it should live to text another day.

The drop box

For this test, the phone is placed on suction pads fixed to an arm that slides up and down a 6ft tower. Rashly, I decide to test my own phone, a six-year-old Nokia 1100. Smith looks on nervously as the phone zips up to ear height before crashing down on to a slab of concrete. Bits fly everywhere. But the injuries aren't as bad as they look; when I put the battery back in, bash the rubber keypad back into place and stick the cover back on, the screen flashes into life. Even the built-in torch (very handy, you know) still lights up.

When they do this test for real, they film it with a high-speed camera that can shoot at 100,000 frames per second. Smith plays a video of an N79 hitting the concrete – in slow motion you can see it bend and buckle as a ripple passes across the keypad. The sliding cover seems to come away from the handset but then it returns to its original shape and works fine.

The scuffer

You could pay a man to stand in a room for two weeks pulling a phone out of his pocket and stuffing it back in again, or you build a machine to do it. For Smith's "jeans test", a leg cut from a pair of child's jeans ("So we don't have to pay VAT," Smith says) is suspended between two clamps. The clamps are attached to a rocker that turns the trouser leg into a kind of denim see-saw. The phone is put inside, and slides up and down the leg 500,000 times. Smith then checks it for scuff marks. "If there's a problem we'll send it back to the designers, who can change the thicknesses, coatings or materials."

But there are worse places to be if you're a handset. "A woman's handbag," Smith says, "is one of the most damaging environments for a phone." To simulate the effect of being buffeted by make-up, purses and other bag-dwellers, Nokia phones are put in the "deburring machine" – a vibrating trough full of hard plastic chips. "The last thing you want is for the '0' button to fade," Smith says. Or, heaven forbid, the Nokia logo.

The microscopes

Once the phones have been dropped, cooked, frozen, rained on, and squished, they're taken downstairs, where the technical stuff happens. Turning a phone on after a test shows that it works, but by delving inside the technicians can check every component.

First, they set a phone in a mould and pump it full of clear plastic, which sets hard. They can then saw it in half to see a cross-section of the phone. By sticking it under a microscope or inside an X-ray machine, they can spot tiny failures. "Even a small mark on a chip could be something that gets worse," Smith says.

To look even closer they have an electron microscope, which can magnify up to 100,000 times. A screen above the controls shows stripes a few inches thick. "Those are the layers of paint – the primer, base coat and top coat – on the battery cover," Smith says.

The human

These labs are abuzz with cutting-edge technology, but robots, pneumatics and microscopes don't always have the answer. A man called Stan used to do "insertion testing" – he would plug charger cables in and out, or slide Sim cards into their slots. When Stan retired, he was replaced with a robot named in his honour. But after a few weeks, Robostan was decommissioned. "It would put memory cards in at exactly the same angle every time," Smith says, "but that's not how humans behave."

Nokia now does insertion testing by hand; Robostan sits inside a glass case like a museum piece. "We keep him here to remind us that technology can't do everything," Smith says.