Why are HDD platters harder than the floppy/ZIP discs?

wrote:

I noticed your one of those to stupid to use a spell checker.


Two grammar mistakes in a one-line spelling flame is pretty impressive.

I normally try to avoid these sorts of post, but this one was just /too/
tempting!

David Brown wrote
wrote:

I noticed your one of those to stupid to use a spell checker.

Two grammar mistakes in a one-line spelling flame is pretty impressive.

I normally try to avoid these sorts of post, but this one was just /too/ tempting!

Yeah, absolutely classic footshot |-)

lid wrote
Rod Speed wrote:
wrote

you turn off the HD the heads move very quickly to the inner sector,

Not anymore.

where they sit, as the heads need air to float or lift themselves up

The heads actually fly.

- can't remember the effect that causes this

I believe that its called laminar air flow

Fraid not.
http://en.wikipedia.org/wiki/Laminar_flow

Don't want to get caught in the flame wars but thought some might be
interested in the following:
Back in the days when the magnetic material was stuck on aluminum
platters and lubricant was used Seagate outsourced the coating of the
platters. When they had a disconnect between the number of platters
needed and the number being produced their incoming inspection
department rejected most of the incoming as being out of tolerance. The
platter manufacturer took the rejected platter back and shoved them on
the shelf.
When Seagate needed more platters than production was producing the
manufacturer pulled the previously rejected platters off the shelf and
they miraculously passed Seagates incoming inspection.
I had a kid working in quality assurance at the platter manufacturer.
She was amused at the game.

edfair wrote:

Don't want to get caught in the flame wars but
thought some might be interested in the following:

Back in the days when the magnetic material was stuck on aluminum platters

That was never the case. It was always vaccuum deposited onto the substrate.

and lubricant was used Seagate outsourced the coating of the platters.
When they had a disconnect between the number of platters
needed and the number being produced their incoming inspection
department rejected most of the incoming as being out of tolerance.
The platter manufacturer took the rejected platter back and shoved
them on the shelf.

When Seagate needed more platters than production was producing
the manufacturer pulled the previously rejected platters off the shelf
and they miraculously passed Seagates incoming inspection.

I had a kid working in quality assurance at the platter manufacturer.
She was amused at the game.

Webopedia quote:

Traditionally platters are made of a light aluminum alloy and coated
with a magnetizable material such as a ferrite compound that is applied
in liquid form and spun evenly across the platter or thin metal film
plating that is applied to the platter through electroplating, the same
way that chrome is produced.

edfair wrote

Webopedia quote:

Traditionally platters are made of a light aluminum alloy and coated
with a magnetizable material such as a ferrite compound that is
applied in liquid form and spun evenly across the platter or thin
metal film plating that is applied to the platter through
electroplating, the same way that chrome is produced.

Pity that ignores sputtering. Wikipedia does it much better.
http://en.wikipedia.org/wiki/Hard_disk_platter

As they did it. This is the way the company manufactured Seagate's
platters in the early days, ST225 timeframe.

'Apparatus for manufacturing rigid computer memory disc substrates -
Patent 4620359' (http://www.freepatentsonline.com/4620359.html)

edfair wrote:

As they did it.

As they did what ? Stupid not quoting any of the context.

This is the way the company manufactured Seagate's
platters in the early days, ST225 timeframe.

'Apparatus for manufacturing rigid computer memory disc substrates -
Patent 4620359' (http://www.freepatentsonline.com/4620359.html)

Doesnt even discuss how the magnetic material is applied to the substrate,
in fact it says very explicitly that that step isnt covered by the 'invention'

quote:

With the present machine, the disc exits the manufacturing process as a
finished disc substrate, ready to go into wet processing for the
depositing of a magnetic coating. Such wet processes are well known to
those skilled in the art and are not part of the present invention.
Substrates made by this invention could just as easily be coated by
conventional magnetic oxide or by plating or depositing processes or
could even be used in applications entirely different than magnetic
coating or memory use.

Your choice. You made the statement that vacuum deposition was the
only way. Seems that the patent holders know of several others and
specifically mention that the wet process is well known to practitioners
of the art.

Are you a practitioner?