[donminion]

hi guys! new here so go easy on me.

im trying to cut some 2mm alu on my 6040.

ive tried a few things now, but keep getting burring & well im getting fustrated with it.

endmills ive tried are a 2 flute 3mm carbide & a 3mm 4 flute tialn. the carbide bit started smoking, so i stopped, i think its dull now.

DOC ive tried 0.5mm & 0.3mm.

tried max feed rate & tried all the way down to 20%, 100% is 1500mm

tried with max rpm 24000, 20,000 15000.

tried using spray lubricating oil.

ive just ordered a 2 flute tialn as they seem to hold the heat a lot better.

can anyone with this machine recommend a decent 3mm endmill & some guide on the settings?

[donminion]

well I think im sorted. don't know why im using tialn bits on alu after reading around, single or 2 flute carbide seem to be what I want.

are these going to work?

2 flute 45' degree high helix carbide?

just ordered some anyway. the place I order from recommended them?

ive been messing with some 2mm 2 flute carbides. got the burred edges to a minimum but its still there slightly.

any tips anyone?

[Palmhoej]

Hey donminion.

You need to calculate your speeds and feeds on the basis of your bit diameter and how many flute you have on it. Try to imagine that we are going into super slow motion and watch our cutter going into the material. You can almost intuitively imagine how the cutter cuts of a chip as we force it into our material. If we fix our speeds (RPM) and go fast into the material (high feeds) we will get thicker chips and vice verse i we move our bit slower into the material (slower feeds) we will get thinner chips. If we keep slowing down we reach a point were our flute does not cut on every revolution, but it will only scrape the material. This is basically your situation. This means that the flute will only produce a chip on say maybe every second revolution, resulting in dulling of your edge and heat building up. The heat is basically what burs the edge of the aluminum.

If we use a cuter with many flutes we will either have to slow down our speeds (RPM) or speeding up our feeds (mm/s). The problem here being that the 6040 machine is not very rigid, which limits the feeds if we do not want to lose steps and precision. Okay, so why don't we just reduce the speed? Well the torque on these machines are not the best at low speeds. They like to go fast. This means that our only viable option is us a single flute router bit, so we can have high speeds and relative low feeds.

So the message is that you basically have to calculate these parameters every time you change material, bit diameter, # of flutes, depth of engagement, feeds and speeds. Not saying i always go with the obtaining result, but it does give you a ballpark number. You can use this free calculator here: FSWizard - Free Advanced CNC Speed and Feed Calculator

As an example this is my favourite settings when doing aluminum:

Carbide single flute cutter (cheap ebay bit).
Diameter: 6mm
Feeds: 800 mm/s
DOC: 0.8mm (Depth of engagement)
Speed: 20k rev/min

https://www.youtube.com/watch?v=6W5K4rdEuN8

Hope this helps

[G59]

Uncoated carbide or at most TIN coated carbides should be OK. If using 1/4" end mills, then I would get HSS. Under 3/16", get carbide for the increased rigidity. The TIALN coatings are good for metal, but are too rough and aluminum likes to stick to it. Maximum of 2 flutes unless you can really push the cutter hard enough for 3 or 4 flutes to get decent chips.
Your problem is too much spindle speed for the feed rate you are using. Your basically rubbing the material off instead of cutting it. Also, coolant works well in aluminum.

[donminion]

hi guys. thx for the response. I kind of figured it all out anyway. but cheers though :cheers:
valuable information really.

im currently using 3mm solid carbide 2FL for pockets etc & using single flutes for profiles & cutouts.

I am kinda new to cnc's so im always learning. the TIALN bits I have work great on copper but as G59 said. alu just sticks to them.

do any of you know anything about thread tapping on this machine? I want m3 & m4 taps that's all.
how would I go about doing it? do I need an rs485 adapter thing & how do you set it up & program it?
don't know if its even possible?

[Palmhoej]

Rigid tapping is out of the question. One would need a spindle with speed feedback, but even if a 6040 had this option it would be way out of its torque range.

Thread milling might be an option, using something like this:
Millipro Miniature Thread Mill 0 5ISO M3 x 0 5 TiAlN | eBay

I dont know if it would be rigig enough, but i think its possible. Check this youtube link out:
CNC Machining - How to Thread Mill an AR-15 Buffer Tube - Tormach PCNC 1100 - YouTube

But how one would write it in a g-code, i would not know. I am using MasterCam, and i guess, that it would be an option, but i am not sure.

[donminion]

cheers dude. I was actually looking at this method as an option. I think I could do this actually by doing a bit of chamfering & then using a swirl profile cut at the right pitch.
I couldn't find the endmills anywhere so im chuffed. thanks a lot.

id imagine rigid tapping is out the limits of this machine tbh. maybe not for smaller m3 & M4 if I could get the spindle tuned & have a way to generate the code. but I guess that's a lot more work to sort out.

again thanks a lot :cheers: