Hi, I'm very new to machine work but have bought a small mill. I just got some end mills 4mm-20mm, and in using the 16mm one the first time burnt out the cutting tips on the face which I'll get sharpened, but I realized I have no idea of the rpm's I should be running it at.
I will be primarily be using the smaller ones ,<16mm on mild steel at this stage. Can some tell me how I determine the correct spindle speed to run these cutters( they have 4 flutes).
Thanks for the help

try this cutter speed guide

http://img.photobucket.com/albums/v6...ograph0001.jpg

The imperial formula is:

RPM = (4*C.S.)/D

Where:
4 = Constant
C.S. = Cutting Speed (From chart for material type and tool material type)
D = Diameter of work(lathe) or cutter(mill)


Feedrate = Chip load per tooth * # of teeth

tbonesmith,

There are too many unknown variables for us to give you a definitive answer. For example, are you using HSS or carbide bits. Are you roughing, finishing, slotting or facing. What is the HP of your machine? How rigid is your machine. All of these and more contribute to a proper answer.

Here is a link that will give you some background.

http://en.wikipedia.org/wiki/Speeds_and_feeds

I have provided numbers from the "Machinist Toolbox" application. I would consider these the maximum speeds and feeds for roughing and finishing with HSS and carbide.

To get you started, I would cut these numbers in half and use coolant. If you are going to be serious about what you are doing, I would also recommend getting a copy of the "Machinery's Handbook and read up on speeds and feeds.

Also, listen to your machine. If it sounds good, it probably is good. If it doesn't, it probably isn't. Adjust accordingly within the limits of your machine.

Good luck,

Drew

OPERATION TYPE= Roughing
MATERIAL= Carbon Steel 1018 - Plain (100-125 HB)
SURFACE SPEED= 78 FPM
ENDMILL MATERIAL= HSS
ENDMILL DIAMETER= 0.62992 inches 16 mm
LOAD PER FLUTE= 0.00275 inches
NUMBER OF FLUTES= 4
SPINDLE SPEED= 472 RPM
FEEDRATE= 5.192 IPM 131.8768 mmPM
MAX Radial Depth of Cut= 0.25197 inches
MAX Axial Depth of Cut= 0.53543 inches
MATERIAL REMOVAL RATE= 0.70046 in³/min
MATERIAL POWER CONSTANT= 0.6
REQUIRED HORSEPOWER= 0.49444

OPERATION TYPE= Finishing
MATERIAL= Carbon Steel 1018 - Plain (100-125 HB)
SURFACE SPEED= 78 FPM
ENDMILL MATERIAL= HSS
ENDMILL DIAMETER= 0.62992 inches 16 mm
LOAD PER FLUTE= 0.001375 inches
NUMBER OF FLUTES= 4
SPINDLE SPEED= 472 RPM
FEEDRATE= 2.596 IPM 65.9384 mmPM
MAX Radial Depth of Cut= 0.0126 inches
MAX Axial Depth of Cut= 1.25984 inches
MATERIAL REMOVAL RATE= 0.04121 in³/min
MATERIAL POWER CONSTANT= 0.6
REQUIRED HORSEPOWER= 0.02909

OPERATION TYPE= Roughing
MATERIAL= Carbon Steel 1018 - Plain (100-125 HB)
SURFACE SPEED= 600 FPM
ENDMILL MATERIAL= CARBIDE
ENDMILL DIAMETER= 0.62992 inches 16 mm
LOAD PER FLUTE= 0.00275 inches
NUMBER OF FLUTES= 4
SPINDLE SPEED= 3638 RPM
FEEDRATE= 40.018 IPM 1016.4572 mmPM
MAX Radial Depth of Cut= 0.25197 inches
MAX Axial Depth of Cut= 0.53543 inches
MATERIAL REMOVAL RATE= 5.39892 in³/min
MATERIAL POWER CONSTANT= 0.6
REQUIRED HORSEPOWER= 3.811

OPERATION TYPE= Finishing
MATERIAL= Carbon Steel 1018 - Plain (100-125 HB)
SURFACE SPEED= 600 FPM
ENDMILL MATERIAL= CARBIDE
ENDMILL DIAMETER= 0.62992 inches 16 mm
LOAD PER FLUTE= 0.001375 inches
NUMBER OF FLUTES= 4
SPINDLE SPEED= 3638 RPM
FEEDRATE= 20.009 IPM 508.2286 mmPM
MAX Radial Depth of Cut= 0.0126 inches
MAX Axial Depth of Cut= 1.25984 inches
MATERIAL REMOVAL RATE= 0.31762 in³/min
MATERIAL POWER CONSTANT= 0.6
REQUIRED HORSEPOWER= 0.2242

Try this site: http://torchmate.com/reference_tables/index.htm

lots of neat tables to print out .
but all in US feet per inch -- you do the math
FBBob