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November 25, 2008

Nokia reliability labs – stress test

SOUTHWOOD, England – In the final part of our series on testing (though we still have analysis to do) we take a look at stress tests. I tend to keep my phone in my front left pocket. That way I always know where it is (alongside my keys) and if I don’t feel it there, I know it’s missing so I naturally look for it. Some people though, keep it in their back pockets. I’m not sure why. But Nokia has a test for it.

The three-point bend simulates a 15-stone man sitting on a hard chair, with his phone in his back pocket. It looks nothing like a 15-stone man sitting on a hard chair but the effects, we’re told, are the same. I feel the N79’s pain when the powerful metal press lowers down on the device, bridged across two holding stumps, pushing the middle downwards to form an unlikely U shape. The phone survives, only to be hit again. Relentlessness, is key in these tests, for the 15-stone man who keeps his phone in his back pocket tends to sit down quite regularly (I know I do!).

Since Ngage gaming was introduced earlier this year, a whole new range of abuse has been unleashed on Ngage-enabled devices. The twist test, erm, tests how well the devices stand up to crash bang gaming. When playing slightly more aggressive games, device owners tend to hold the device at both ends and they’re hands don’t always move in the same direction. In fact, sometimes they move in two different directions, thus causing the device to twist in the middle. Once again I feel the N79’s pain as the device is clamped into the machine top and bottom, before the top moves in the opposite direction to the bottom. The phone strains, but doesn’t break. I’m sure they can turn the twist dial up and make the phone break, but they don’t need to. I don’t think even Hulk Hogan could make the phone twist any more. It’s gotta hurt.

The final, and possibly the most sophisticated stress test, involves dropping the phone. Not just standing on the edge of the multi story car park and letting go (although they do that too) but using a special machine, designed and built solely to drop phones. Robert Johnson points out that many digital camera manufacturers don’t run drop simulations, but the camera is just one of the many things Nokia tests after the drop test. Their ambition is to make sure the pretty delicate camera still works after taking a hammering. No mean feat.

Using suction, the device is attached to specially mounted suckers on the drop machine. It can be positioned any way the testers like, to simulate any kind of drop. The key is the ability to make the same phone drop in the same position time after time. Consistency is the king to the relentless queen here.

At the bottom of the box sits a foot square concrete pad. The same pad used in all the Nokia drop test machines (which are all identical, too) in the 11 test centers around the world. It looks like a bit of pavement (or sidewalk, depending on which side of the Atlantic you’re on). The test itself is over in a flash. The suction holds the phone in place for the majority of the fall, until it lets go about 18 inches above the ground. This means it can manage the fall, but not falsely interfere with it. This needs to happen to ensure the same type of fall can be created time after time.

Capturing the fall itself is a £20,000 camera which shoots at 100,000 frames per second. You can see what happens at the end of the fall in the video below. It sure seems cruel, but it’s what needs to happen. In a lot of instances, the battery cover comes off and the battery pops out. Whilst this is a positive thing in that it helps displace the energy created in the impact, it actually happens because the battery cover is the weakest part of the device. Not because it’s not good at what it does, but that it needs to be easy to remove and put on. It’s a bit of a catch 22, really.

So there you have it, all the testing we got to see in the Nokia reliability labs. Our final piece will look at the analysis that goes on. Check back tomorrow for an update.