[schiada96]

I am new to machining.
I need to know how long it will take to drill a .272 dia hole 3.3 in deep in 1018.
Also .272 dia 1.9 in deep in 4140.
We will be using a HAAS VMC.
Is their a formula to determine these caculations?
Thanks
Jeff

[dave3431]

Yes, there is a formula, it can be found in Machinery's Handbook
These values are for optimum conditions and as a general rule, you should reduce by 50% for a start point and work up from there.

[BMackinnon]

For the 1018 try 1200RPM and 7IPM - .450 for first peck and .235 for following pecks with full retract.

For the 4140 try 750RPM and 3.5IPM - use a chip break cycle with .020 for chip clearance and .1875 for pecks.
With the 4140 you just want to avoid heat so you dont workharden the part, slow keep a slower RPM to avoid the drill from rubbing and maintain a good chipload.

Just what I would use for starting numbers.
HTH

[schiada96]

thanks for the info
Jeff