1mm end mill depth of cut in aluminium.

[Nealieboyee]

Hello boys and girls,
Just want to get your thoughts on using a 1mm end mill in aluminium.

What kind of depth of cut should I be shooting for? The alu isn't the best of grades but I'm throwing plenty of coolant at it.
At the moment I'm doing fine machining 0.3mm pockets in two passes. 0.2mm first and then 0.1mm. I'd like to push that to one pass if I can.
1mm 2-flute.
4mm shank
3mm flute length.

Thanks
Neal

[JAZZCNC]

You said it all when mentioning the grade. Nobody can tell you what to use without knowing the grade and even then with small cutters, the machine stiffness becomes a large factor.

Unfortunately, it's going to be trial and error. If your machine is stiff enough and the spindle is ok on the runout plus spins fast enough then I can't see why 0.3mm shouldn't be possible with good cooling.

[Nealieboyee]

You said it all when mentioning the grade. Nobody can tell you what to use without knowing the grade and even then with small cutters, the machine stiffness becomes a large factor.

Unfortunately, it's going to be trial and error. If your machine is stiff enough and the spindle is ok on the runout plus spins fast enough then I can't see why 0.3mm shouldn't be possible with good cooling.

Thanks Jazz. Yeah was hoping someone would confirm what I thought. I'm running the spindle at 24000rpm with a more precise collet because of the smaller end mill. Flute length could be shorter but I'm working with what I have. Flooding it with paraffin ��

[JAZZCNC]

Thanks Jazz. Yeah was hoping someone would confirm what I thought. I'm running the spindle at 24000rpm with a more precise collet because of the smaller end mill. Flute length could be shorter but I'm working with what I have. Flooding it with paraffin ��

Ye, sometimes you just got to be patient and accept it's a slow job. Or you go for it and risk a cutter or two. Me personally if it's just a one-off job then I'd air on the side of caution so don't break cutter but if it's a job I'm going to do regularly then I'd sacrifice a few cutters to find the optimum cutting parameters. It's pays back long term.

[cropwell]

For Ali I use half the cutter diameter as the DOC, but I use Open Architecture cutters like these https://www.sorotec.de/shop/Cutting-Tools/sorotec-tools/1-8-tools/1-8--Shaft-Mill-Tools/2-Flute-ALU/ Spindle is 12000 rpm and feed is 5mm/sec. It seems slow, but maybe I am just cautious. Most of what I do is one off. Lots of air to clear chips, and my coolant is WD40 and this gives OK results on that soft sheet ali 1050 grade.

But it did take a few broken cutters to get there.:witless:

[JAZZCNC]

For Ali I use half the cutter diameter as the DOC, but I use Open Architecture cutters like these https://www.sorotec.de/shop/Cutting-Tools/sorotec-tools/1-8-tools/1-8--Shaft-Mill-Tools/2-Flute-ALU/ Spindle is 12000 rpm and feed is 5mm/sec. It seems slow, but maybe I am just cautious. Most of what I do is one off. Lots of air to clear chips, and my coolant is WD40 and this gives OK results on that soft sheet ali 1050 grade.

But it did take a few broken cutters to get there.:witless:

Your very brave man cutting 1050 with those settings as your doing a lot of rubbing rather than cutting.!
12K is far too slow for 1mm cutter, to be honest so is 24K, should be more like 40-50K. Also, the 50% Diameter rule doesn't often work out too well for sub 1mm cutters. For small cutters below 3mm, I wouldn't go much more than 30% and down to 10% for sub 1mm.

[cropwell]

Hi Jazz,

I used to cut at 24000 rpm, but got far too much clagging on the cutter. I think the OA cutters make a vast difference as those settings with a cheap chinese carbide end mill just meant el snappo.

Not had much luck with anything small - 0.2 mm cutters will break if you look at 'em funny. I lost too many just putting them in the collet.

Sub 1mm drilling is another matter, no sideways forces and for PCB isolation routing I use tapered engravers, they are cheaper and last longer. I haven't tried them on that soft as sheet ali, but I guess it would look a bit chewed.

Happy Sunday,

Rob

[JAZZCNC]

Hi Jazz,
I used to cut at 24000 rpm, but got far too much clagging on the cutter. I think the OA cutters make a vast difference as those settings with a cheap chinese carbide end mill just meant el snappo.

You do realize that OA is just bullshit for high helix. All cutters are open architecture.!!

The reason you clagged up was melting because was rubbing rather than cutting because the feed rate was too low. At the lower rpm your not rubbing as much but you still rubbing to some degree which is causing excess wear and a poor finish. It's a common mistake to think melting is because going too fast when it's actually the opposite.
Unfortunately with small tools it's a fine balance between too slow and too fast causing high tool pressure which is what snaps tools. Throw shity material into the mix with it's hard and soft spots plus a slightly wobbly machine and it soon becomes a cluster F'@'K..

Chatter is another problem where going faster can actually reduce chatter by increasing tool pressure which pushes the tool into material harder so reduces chatter. The trick is not overdoing it and lowering the RPM.

[cropwell]

You do realize that OA is just bullshit for high helix. All cutters are open architecture.!! .

No I didn't realise it was bullshit. I thought it was a combination of a fishtail end and a more open helix. I have found end mills with a flat end are much more prone to clagging.

BTW Sorotec recommend a spindle speed of 50K 7mm/sec feed and 1 or 2mm/sec Z feed for up to 1.2mm cutters. With those parameters I would expect to melt through the metal unless you clear the debris. Chip size must be fine dust.

For 2 and 3mm cutters I use single flute with more success.

[JAZZCNC]

No I didn't realise it was bullshit. I thought it was a combination of a fishtail end and a more open helix. I have found end mills with a flat end are much more prone to clagging.

It's mostly down to helix and if polished flutes or not. If you don't need flat bottom cutting then you are always better buying end mills like slot cutters which have more clearence.
For finish passes I actually prefer HSS as the slower feeds n speeds seem to give a better finish.


BTW Sorotec recommend a spindle speed of 50K 7mm/sec feed and 1 or 2mm/sec Z feed for up to 1.2mm cutters. With those parameters I would expect to melt through the metal unless you clear the debris. Chip size must be fine dust.

Yep it requires lots of chip clearing and it does come off like a fine slurry. I recently visited a place in Leeds who engrave and cut with tiny cutters using 100k+ HF spindles and what came off was like a fine grinding paste. Would you believe they hardly break cutters from actually cutting, they break them mostly when replacing or catching on stuff. However, they grind there own so it's no big deal to them.

[cropwell]

I recently visited a place in Leeds who engrave and cut with tiny cutters using 100k+ HF spindles and what came off was like a fine grinding paste. Would you believe they hardly break cutters from actually cutting, they break them mostly when replacing or catching on stuff. However, they grind there own so it's no big deal to them.

Amazing, I visited a place that drilled stainless steel filter discs for a certain phamaceutical company in Nottingham. Their finest holes were much smaller than a human hair and they were using carbide drills on a 1/8 shank. They wouldn't give me info on the feeds and speeds though.

[JAZZCNC]

Their finest holes were much smaller than a human hair and they were using carbide drills on a 1/8 shank.

Yes, these were ground into 4" long 1/8 shank carbide blanks and there most commonly used size was 0.1mm. I could have sat and watched the grinding machine all day it was amazing. Don't think I could have touched the endmills without breaking one so how the hell they get a machine to do it blows my mind.!