Feed Rate Calculation based on Tool Length

[nckiddo]

Hi Everybody:

I wonder if there is any set of formule that could be used to adjust the the feed rate when cutting with long tools.

Something like if a .500" dia tool that sticks 11" from the spindle face cutting aluminum at 6000 rpm ... or is 6000 rpm too high ....

How does the tool length relates to the cutting parameters of a tool such as rpm , feed , Axial and Radial Depth of cut...

It will be really great if some of you could explain the relationship

Thank you all

NcKiddo.

 

[Compositepro]

I can't answer your question directly, but just yesterday I read a highly relevant article in the Sept. American Machinist about the advantages of using plunge milling for deep cuts that require long tools.

http://www.americanmachinist.com

 

[saberblue]

This gets to be a question of machine rigidity and how "stiff" the tool shank and the machine are. Typically the longer the tool "over hang" the more vibration is generated by the load - unload of the tool - you will also find that there are critical lengths where just a little longer or shorter may change the vibration patterns significantly --

good luck and happy experimenting


A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

 

[dicer]

In the machinist world there are formula's. And there is experience.
With all the variables the formula's are just a starting point. Like someone mentioned it all depends on such things as rigidity, etc.
Okay you said 11" from the spindle face, how long is the tool holder? How long is the flute length?
If the tool is long 6k rpm is probably way too fast. Sometimes to satisfy the setup and other conditions you end up running it like its the hardest material there is even if its aluminum.
You may have to run 100 rpms and feed real slow to keep the chatter out. Its not a calculate deal it a try it and see type of deal.

 

[Redlineal]

The answers already posted are quite correct in what they say.
The parameters you have quoted are achievable but are dependent on many more parameters such as:-
• Does it have to be ½” all the way down?
• Shank material of cutting tool
• concentricity of tool within the toolholder (not just at the cutting point)
• The type of toolholder BT40 or 50.
• The cutting geometry of the tool itself
• Stability of the component
• Component material

To name a few

6000 does seem a little excessive but is by no means unachievable using the right equipment and shallow depths of cut.

These people specialise in this sort of stuff

http://www.walter-tools.com/sandvik...c0c12574bf002a4fc9/$FILE/Mould_Die_en_NEW.pdf

Hope this helps and I aint too late, but I just signed up

 

[ykaero]

Main issue in long tools is tool vibration. Some parameters like feedrate, RPM, depth of cut etc. must be adjusted perfectly to prevent vibration. But it is really hard work, you have to use some spacial methods for determine what they should be.
I heard that there is a test named hammer test to determine your spindle speed due to your spindle, holder, tool length, tool type etc. in this method, you clamp your tool to the spindle and then you hit your tool tip by a special hammer that connected to computer. And computer say you optimum spindle speed and feedrate.

http://www.mmsonline.com/articles/minimizing-vibration-tendencies-in-machining.aspx