[AArdvark_76]

Hi, i am new to CNC machining and so far i have been learning by trial and error working mainly with MDF. however i need to machine some thin 1mm aluminum i want to cut some shapes out of it . my ultimate goal is to find out what speeds and feed rate to use but also at the same time some help to understand the tool's datasheet so i can calculate this for the future.

the machine is an Itech 6090 generic Chinese made but a bit studier than the cheap ones on ebay. the tool i need to use id a Dormer 3mm end mill 4 flutes here is its datasheet https://docs.rs-online.com/9913/0900766b80d1c5d1.pdf

when ever i read about how to calculate RPM and feed rate it says look up the datasheet for chip load and SFM neither of which i can see in this datasheet.

can anyone help me work out what i should be using for RPM and feed rates?

[joeavaerage]

Hi,
the first thing is to set the surface speed. This is in effect a thermal barrier. For instance, aluminum with uncoated carbide has a recommend surface speed of 250m/min up to 500m/min.
If you go faster, you risk heat buildup in the tool or workpiece or both resulting in poor finish and poor tool life. If you go slower the no trouble, you'll get great tool life but take longer to
do the job.

Lets say you choose some intermediate speed, say 300m/min.

6mm tool : RPM= 300 / (0.006 x PI)
=15915rpm

8mm tool: RPM=300 /(0.008 x PI)
=11936rpm

10mm tool: RPM=300 / (0.01 x PI)
=9549rpm

etc...

That gives you a reasonable rotational speed....but what about feed rate?

I use some very small tools and they are tender and break if you push them too hard. For such tools I recommend 1% diameter of the tool per flute per revolution.

Lets say you have a four flute1.5mm tool, and you spin it as fast as you can, say 24000rpm.
Feed Rate= (1% of 1.5mm) x 4 x 24000
=1440mm/min

If you have a four flute 6mm tool at 15915rpm, it will be stronger, and you can probably cut 1.5% of diameter per flute per revolution.
Feed Rate= (1.5% of 6mm) x 4 x 15915
=5729mm/min

These are guidelines....you might try slower speeds and work your way up. It will depend on other factors like flood cooling or air blast cooling, the power of your spindle and rigidity of the machine.

The essence is that the rotational speed is set by the thermal properties between the tool and the material, while the feed rate is determined by the strength of the tool, the ability to flush chips away
from the cutzone and spindle power.

Craig.