RE: [CAD_CAM_EDM_DRO] The cutting edge?

I am by no means an authority on this subject, so if you get contradictory
answers they are probably correct.

RPM is a function of cutter diameter. Cutter speed is actually calculated in
surface feet per minute and then you need to divide that by your cutter
circumference to get the RPM. Looking in my Armchair Machinist program it
gives the SFM for aluminum as 550 SFM for high speed steel and 1100 SFM for
carbide with an 1/8" bit that works out to about 16,000 and 32,000 RPM

Feed rate is based upon the chip load you want per cutter tooth, so it is a
function of number of flutes, RPM, and desired chip load. At 10,000 rpm with
a single flute cutter and a .005" desired chip load you need 50 IPM of
travel.

For the styrene your biggest concern will probably be not melting it. If
your RPM is high and your feed rate is low you will probably get melted
spots and then have problems with the soft plastic sticking to the bit. You
will probably need to play with fast feeds and slower RPM and find what your
machine is happy with.

Regarding the bit, single flute will give you more chip clearance and more
flutes will give you a better finish at the same RPM. I have been told that
single flute works better for very soft materials.


Tim
[Denver, CO]

> -----Original Message-----
> From: rhj-rbj@... [mailto:rhj-rbj@...]
> Sent: Friday, July 09, 1999 1:19 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: [CAD_CAM_EDM_DRO] The cutting edge?
>
>
> From: rhj-rbj@...
>
> Hi all, Thought I might try to open another thread, that of
> cutting and cutting speeds for various materials. My first
> interest is for routing through styrene sheet in the 0.7mm to 2mm
> thickness range, doing outline cutout operations. Can people
> advise the best type of tool for that. (i.e. HSS or carbide or?
> single point, twin flute etc.) What r.p.ms and what gantry travel
> speed. Similarly what about for Aluminium soft sheet in the same
> sort of thicknesses. thanks Raynor J
>
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