[PhilipTheArab]

I am trying to understand the basics of milling while trying to put my DIY milling machine into use.


trying to mill 20 mm circle cut (2d tool path) in 8 mm steel plate

I used the following
feed rate : 90 mm/minutes
tool : 4mm end cut/ 4 flutes/carbide
stepdown : 0.1 mm

things going very well with no vibration please see the short video


My question : I have the metal shavings welded to the edge of the cut . Is it because I am not using cooling water? and running at high 5000 rpm. I do not see any indication of excessive temperature. I can touch the plate near the working area not hot at all. For sure the tool maybe very hot.

Second question : how do I remove the chips every few minutes? if I press the pause button on the axis interface screen and raise the tool up along z axis and clean the chips, and then hit resume button on the axis interface screen is this the proper way to do it?

Many thanks

Note :

1-this is not the spindle I intend to use. just for experimenting. Also I will place order for cooling mist nozzle.* I am only investigating the potential of the DIY machine to be or not to be.
2- The other holes in the plate you see are made by laser machine.



Philip

https://www.youtube.com/watch?v=OFd4Y3d77OM

[joeavaerage]

Hi,
as a broad rule for coated carbide tools in steel the surface speed should be 100m/min.

In your case:
diameter=4mm =0.004m
circumference= 0.004 x Pi = 0.01256m
surface speed@5000rpm= 0.01256 x 5000=63.83 m/min.

You should be good with those rpms and an uncoated tool. As a rule if you exceed the target surface speed you generate too much heat and destroy the tool.

Now look at the chipload:
Time per one rotation = 1/ 5000 min=0.00002 min or 0.012 seconds per rev.
Feed Rate= 90mm/min =1.5mm/second
Chip size= 0.012 x 1.5 =0.018 mm/tooth = 18 um/tooth
Chipload= 0.018 x 4 = 0.072mm = 72um

So your chipload is about right. If you increase the chipload excessively, that is increase the feed rate too much, you risk over torquing the tool and breaking it. If you decrease the chipload too much
you risk 'giving the workpiece a good rub' and generate heat but no chips. The idea is that you are trying to create chips that carry away as much heat as possible AWAY from the workpiece.

I believe your cutting parameters are about right, I would suggest therefore that you are re-cutting chips, and that is a sure receipe for welding chips. Try flood cooling, its more about removing
chips from the cutzone than it is cooling, removing chips is vital.

Craig

[PhilipTheArab]

Very helpfull

I will use this method for calculation.

Good since you are using metric units

what is the limit surface speed for steel and carbide tool in metric?
And the chipload per tooth limit?

Thank you Craig

[PhilipTheArab]

I could not edit my last post

I found the limits


I do not see the depth of cut per pass (stepdown) figure used in the chip load calculation

[Halfnutz]

Try just blowing out the swarf with an air compressor. They go everywhere, but it will get them out of the way.