Lubricating the drive

e4Engineering.com ^ | 8/25/04

[sionnsar]

"sterically hindered polyester" That's gotta hurt...

There was a lot of 70s polyester that deserved to be hindered -- by whatever means available...

[Conspiracy Guy]

Yep

[Conspiracy Guy]

Thanks Cliff

[Robert A Cook PE]

"Yodeling in the gully.

Salivating tulips...

[Calvin Locke]

30,000 rpm is the limit.

Myth Busters mounted a CD on a shaper, and I think they had to boost the speed to get it to shatter. Around 30K RPM, iirc.

Routers, and plain old CD drives just wouldn't do it.

[null and void]

That's gotta hurt.

[Bloody Sam Roberts]

Salivating tulips...

Jackin' the Beanstalk

[Robert A Cook PE]

But a CD is a simple plastic disk, only modestly balanced.

A hard is machined aluminimm, much srtonger, thicker, and balanced. Surface is smoother too -> less vibration.

[PoorMuttly]

Muttly hopes it will stand up better than whatever they currently use to his monthly "dip the computer and t.v. in Bleach" policy.

You never can be too sure these days.

Next time, however, Muttly intends to un-plug the t.v. first. Well...the new t.v. It did seem to fix the problem though...

[DouglasKC]

I personally think that we're about to see the end of mechanical storage entirely. It's my guess that with the introduction of the S-ATA standards that we'll be seeing solid-state memory. Another option is massively multi-layer 3D read holographic storage (similar in concept to multi-layer DVDs but much higher capacity and faster access).

Agreed. Dress it up all you want, but really a hard drive nothing more than an elaborate tape recorder.

[Calvin Locke]

But a CD is a simple plastic disk,

A bit more, but yes, I doubt it was designed for the desired speeds (xfer rates) nowadays.

BTW, last time I disassembled a hard drive, probably a 3.2GB, the disks were less than half the thickness of a CD, iirc.

[Flying Circus]

Just to nitpick, tiny arm that reaches over the disk is not the slider, but the Head Gimbel Assembly (HGA). The Slider is the part at the end of the HGA that contains the read and write heads and acts to control the distance of the heads from the disk.

Stiction is an interaction of surface energies driven by the micro-roughness of the disk much more than the lubricant. When you shut your drive down, the head automatically goes to either a rough area at the center ring of the disk or a ramp off of the disk because if the head were on the disk when it stopped the stiction would either seize the drive or rip the heads off.

Finally, 10k RPM is not becoming common but is still a fairly high end drive mostly reserved for servers. Most desktops are doing just fine with 7200RPM. Most mobile drives turn at 5200 RPM but newer high end drives are getting to 7200RPM. The fastest drives are up to 15k RPM but are a very small market.

[Flying Circus]

That is an interesting link, but it is a bit outdated. The newest generations of drives have the heads flying one tenth the distance quoted. The current generation flies around 10 nanometers from the disk or 0.4 millionths of an inch. To put that number in perspective, a nanometer is the equivalent of 10 atomic radii, so the current generation heads are flying around only about 50 atoms above the disk.

[Flying Circus]

HDD disks are either Aluminum or Glass substrate. I think the glass works better in high RPMs applications because it distorts less from the centripetal forces.

You are right about the need for balence. Especially in the high speed drives that get stacked in big arrays in servers. Put 20 drives side by side and run them at full speed and you get a lot of vibration.

[Straight Vermonter]

Even worse, I've noticed recently on programs like "Engineering the Impossible" that terrorism has become a major obstacle to people investing in daring new technologies. There is no way a Europe-Africa bridge or a space elevator is going to be built if some yahoo can blow them up whenever they like.