Re: [CAD_CAM_EDM_DRO] feeds and speeds.

Hello friends,
in relation to the speed and feed recommendations for mill and turning
inserts you must keep several aspects in mind:
These numbers are made for stiff production machines.
At least on turning inserts they are calculated for maximum metal removal
rate during 20 minutes!!!!!
Afterwards they have to be changed.
So first if your machine is not as stiff as a high volume production machine
go drastically down with speed and feed.
Second If you not want to break a lot of tools then go even more down with
speed and feed. Because only in proved batch programs and rigid set ups you are able to use them.
Third tool life is directly depending on the cutting speed. The curve is like a hyperbola. As slower you go as longer it will last.
But you must select your
carbide grades according to the material you want to work.

My lathe is very rigid and stable but still as a rule of thumb I start for batch
production with 75% of the recommended cutting speed and for roughing with
a feed of half nose radius. 75% of the cutting speed gives you normally 1 hour 20 minutes of tool life. And half nose radius feed
for roughing is a safe approach from where I start playing. for best performance.

So for what you should force your tools and machines if you want to make
a nice hobby job?
Better tinkle a lot with your machine, try out for what it is good and where are
its limits and then make your own rule of thumb for to apply the tooling manufacturers recommended values.

Lets give you an example. The didactic ENCO lathes I know are small and weak
I would start with a positive insert with not more than 0,4 mm nose radius at 40 percent of the recommended speed (4140 =
bonificated chrome molly steel 140m/sec*0,4=56m/sec (which is still above the critical build up speed of 40m/sec)), make narrow cuts
not deeper than 2 mm diameter and start with only a forth of the nose radius 0,1 mm/rev.

The tread started with the the question for speeds and feeds in aluminium.
Aluminium is normally very nasty to work with. It gums up and makes frequently a great mess. For production and everything else I
always use 6061-T6511 or 6064-T6511 aluminium. because even with the H34 grades I had big troubles.

I hope this gives a notion.

Good Luck.
Sven Peter


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