Milling speed using a shell cutter

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Wrightontrack45

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I am using a Straight Shank Arbor 400R Face End Mill Cutter with 4Pcs APMT1604 Carbide Inserts
The shell diameter is 50mm can anyone give me the correct cutting and feed speeds for milling mild steel flat bar.
 
That's pretty much a wide open question . The speed is easily calculated as a starting point , and adjusted as needed for what inserts you're using. Feed is dependent on many things such as HP at the spindle , rigidity of the machine , set up , depth of cut , coolant etc .

Oh , and Welcome back to the site . :encourage:
 
Quick and dirty... 1/4" HSS in steel is 900 rpm. Circumference of 1/4 is .785. Circumference of 50 mm is about 6.28. Divide circ of 50 by circ of 1/4 is 8. 900 divided by 8 is 112.5. Carbide : HSS is close to 4:1, 112.5 X 4 =450 rpm.

Hope someone comes along and passes judgement on this. the source was developed by me in the third quarter of the last century.
 
You generally need slow feed rates if you care about the finish at all. Also these types of cutters can be tough on hobby level mills, will typically get vibrations at some point.
 
The package your inserts came in may have some hints. Most feeds and speeds are a starting point and you adjust based on 'feel', which can take some time to develop.

I tend to run inserts at about 400 sfpm in mild steel. That may be faster than others use.
RPM = SFPM * 12/(PI*dia)
I use SFPM * 4/diameter because I can do that without pencil, paper, or calculator. And these are ballpark anyway.
50mm roughly is 2". So 400 * 4 /2 = 800RPM. 800RPM is 3200 cutters (teeth) per minute. Typical inserts are somewhere around .001 - 003. Inches per cutter. Start at the lower end. So 3200 cutters/minute * .001 inches/cutter = 3.2 in/min.

Metric: SFPM=120 m/min, 800 RPM, .025 mm/cutter, feed = .081 m/min

At the machine I may adjust those from 50% - 200%. And as @mmcmdl said, depth of cut, HP, coolant, etc all play in. Chip color, sound and vibration, are some hints.
 
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Check out Tom's Techniques (https://tomstechniques.com/) for recommended feed speeds (and many other shop tips). The quick and dirty formula for plain-carbon steel is: RPM = 400 / (work or cutter diameter). That's with HSS cutters/drills; double the RPMs for carbide.

If turning a 1" CRS round on the lathe, math is 400 / 1" or 400 RPM. For the mill with a 1/2" cutter (or drill bit), math is 400 / 0.5" or 800 RPM.

Using Tom's recommendation, you'd be 400 / 2" (50 mm) or 200 RPM. You're using carbide so double it to 400 RPM. Depth of cut and width of cut will likely be more of an art than science and is highly dependent on the rigidity of your machine and clamping.

Bruce
 
The formula for calculating RPM for HSS is (Cutting Speed X 4)/diameter
Memorize it, you will need it daily.
This is for HSS, carbide can be run 2-10 times faster.
Cutting speed for mild steel is 80-100 SFPM
Since I pay for my own cutters and no one is paying for my time, I use the conservative numbers.
(80x4)/2=160 for HSS
Double that for carbide =320 rpm.
These are numbers to get you in the correct range, they are not hard and fast.

In my 20 years in the trade, I NEVER calculated chip load or feed rate, that is mostly for CNC.
With a few exceptions, the power feed on manual mills is not graduated in IPM.
Start the feed slow and increase as your eyes and ears dictate.

I have that same cutter on an R8 shank.
 
MrWhoopee said:
The formula for calculating RPM for HSS is (Cutting Speed X 4)/diameter
Memorize it, you will need it daily.
This is for HSS, carbide can be run 2-10 times faster.
Cutting speed for mild steel is 80-100 SFPM
Since I pay for my own cutters and no one is paying for my time, I use the conservative numbers.
(80x4)/2=160 for HSS
Double that for carbide =320 rpm.
These are numbers to get you in the correct range, they are not hard and fast.

In my 20 years in the trade, I NEVER calculated chip load or feed rate, that is mostly for CNC.
With a few exceptions, the power feed on manual mills is not graduated in IPM.
Start the feed slow and increase as your eyes and ears dictate.

I have that same cutter on an R8 shank.
Click to expand...
Are you using the Blue Nano inserts, that is what I am using on EN1A mild steel. My mill is a Warco Super Major Vario
 
Wrightontrack45 said:
Are you using the Blue Nano inserts, that is what I am using on EN1A mild steel. My mill is a Warco Super Major Vario
Click to expand...
I'm still using the no-name Chinese inserts that came with the cutter. Not overly impressed, but for the little I have used it they've been fine.
 
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