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Posted by pmaston on April 23, 2008, 11:07 pm
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If you know a site, or if you have a list of the speed requirement for
turning metals on a lathe, I would appreciate it. On my quick change gearbox
on my lathe it shows the speeds, but I like to know how fast I should have
the spindle turn if I'm turning let's say aluminum and soft steel
maybe...The same maybe, if I could impose for a milling machine as well....I
used to have all this stuff, but whenever my grandson visits me, and he
needs small things, he borrows it, and then forgets to give it back to me.
Then if I need it, I can't put my hands on it....Peter
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Posted by Mechanical Magic on April 23, 2008, 11:43 pm
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Peter,
I don't know of a site with that info, must be somewhere.
But it's rather easy;
Metals have an optimum surface speed, based on tool wear, and
productivity.
Surface speed is how fast the tool travels over the work, in feet per
minute.
FPM for common metals using High Speed Steel tools:
Hard Steel/Stainless 50
Soft Steel/Iron 100
Brass 200
Aluminum 500
(Many other speeds are quoted, this is generic, and nudged for memory
sake.)
So, if you have a 6" diameter steel blank in the lathe. The
circumference is 6" x 3 (Pi) = 18 divided by 12 to get feet = 1.5'
circfunference.
Since steel is 100 fpm, 100 / 1.5 = 66 RPM for the best
productivity.
All these numbers are approximate, too slow increases tool life, fine
for a home shop, that likes to watch the machine. Coolants and lubes
will make a big difference.
Faster wears the tool tip quicker.
Dave
> If you know a site, or if you have a list of the speed requirement for
> turning metals on a lathe, I would appreciate it. On my quick change gearbox
> on my lathe it shows the speeds, but I like to know how fast I should have
> the spindle turn if I'm turning let's say aluminum and soft steel
> maybe...The same maybe, if I could impose for a milling machine as well....I
> used to have all this stuff, but whenever my grandson visits me, and he
> needs small things, he borrows it, and then forgets to give it back to me.
> Then if I need it, I can't put my hands on it....Peter
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Posted by Michael Koblic on April 24, 2008, 2:43 am
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> All these numbers are approximate, too slow increases tool life, fine
> for a home shop, that likes to watch the machine. Coolants and lubes
> will make a big difference.
> Faster wears the tool tip quicker.
Is there not some negative impact on the cutting tool if it is running too
slowly? I have recently gone through the same deliberations and have to say
that good tables were hard to find on the net.
I read a book which included correct speeds in a chapter. Their caveat was
not to let the tool "rub" - whatever that means. My take on it was that this
happens at slower speeds than recommended but could not understand it
completely.
They also suggested that the speeds you quoted should be adjusted according
to the operation: For instance for countersinking they suggested using
speeds 1/3rd of those normally recommended.
There were also notes about the feed speeds and the material of the cutting
tool affecting the correct cutting speeds, so in the end I was rather
confused. Nowadays I rather tend to err on the slow side...
--
Michael Koblic,
Campbell River, BC
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Posted by Karl Townsend on April 24, 2008, 5:40 am
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> There were also notes about the feed speeds and the material of the
> cutting
> tool affecting the correct cutting speeds, so in the end I was rather
> confused. Nowadays I rather tend to err on the slow side...
Sounds like me and the kid working in the shop a few years ago. I was the
tortoise, he the hare. He went fast and broke shit, I finished first by
going slow and easy. But now, he's been a pro for six years. he just plain
works circles around me. He still asks me to do the manual lathe work. The
old guy has a better touch for that.
There are great tables for carbide inserts. Every manufacturer has a web
site for this, giving optimum speed and feed by material for each insert.
Karl
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Posted by Bruce in Bangkok on April 24, 2008, 8:40 am
Please log in for more thread options On Thu, 24 Apr 2008 04:40:19 -0500, "Karl Townsend"
>
>> There were also notes about the feed speeds and the material of the
>> cutting
>> tool affecting the correct cutting speeds, so in the end I was rather
>> confused. Nowadays I rather tend to err on the slow side...
>
>Sounds like me and the kid working in the shop a few years ago. I was the
>tortoise, he the hare. He went fast and broke shit, I finished first by
>going slow and easy. But now, he's been a pro for six years. he just plain
>works circles around me. He still asks me to do the manual lathe work. The
>old guy has a better touch for that.
>
>There are great tables for carbide inserts. Every manufacturer has a web
>site for this, giving optimum speed and feed by material for each insert.
>
>Karl
>
As a sort of rule of thumb erring on the side of slower cutting speeds
with higher feed rates will generally remove more material in a day
then high cutting speeds with lower feed rates.
The lower cutting speeds usually let you get more cuts between
sharpening too :-))
Bruce-in-Bangkok
(correct email address for reply)
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> turning metals on a lathe, I would appreciate it. On my quick change gearbox
> on my lathe it shows the speeds, but I like to know how fast I should have
> the spindle turn if I'm turning let's say aluminum and soft steel
> maybe...The same maybe, if I could impose for a milling machine as well....I
> used to have all this stuff, but whenever my grandson visits me, and he
> needs small things, he borrows it, and then forgets to give it back to me.
> Then if I need it, I can't put my hands on it....Peter