CW wrote:
If that were the case, machine tools would be made primarily from steel.
They aren't. As for the hardness of cast iron, true it is softer than steel
but it's high carbon (graphite) content tends to make it somewhat self
lubricating were steel will gall much easier. This is, of course, metal to
metal contact so really wouldn't apply here. Should have said that in the
first place. As far as stability. No steel will outdo cast iron if properly
stress relieved.

"alexy" wrote in message
...
Steel generally wears better than iron.
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If _what_ were true?

Large beds for metalworking machines are typically made
from cast iron for a number of reasons. The primary reason
is that it is possible to cast the large parts from cast iron.
While there are cast steels, they don't cast as well as iron.
For an appreciable number of units, casting is almost always
the cheapest way to make them

Secondly, cast iron machines easier that steels due in part
to the lubricity provided by the graphite inclusions mentioned
above, and partly because it is softer than steel.

Cast Iron is just as stiff as steel but has better dampening,
again due to the graphite inclusions.

It's good stuff.

But it is not harder or more stable than annealed steel.

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GG