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examorph
27-01-2017, 08:07 PM
Hi guys, so after getting up and running I have got some cheap 2 flute carbide ball nose end mills (6mm roughing & 2mm finishing) for some 3D work. I am trying to figure out what to run them at, so turned to HSMAdvisor which outputted ~10k mm/min at 24k rpm in MDF!! (bit too scary for me :black_eyed:)

- So firstly, am I right in thinking that HSM outputs the extreme limits and as long as I adjust spindle speed and feed rate proportionally I will be OK no matter how high or low (as long as within machines limits)?

- If so, then do the following feeds/speeds look OK for doing some 3D work?
MDF:
20511 20512
Aluminium:
20509 20510
The feed seemed a little high on the 2mm in MDF but as spindle RPM was limited by machine, I wasnt too sure if I could reduce this? Also, should the plunge rate be lower for 3D relief work?

- Other than adjusting step-over to be much finer, is there any need to change other parameters (feeds/speeds) when doing detailed 3D work vs ordinary machining?
Thanks.

paulus.v
27-01-2017, 08:56 PM
In MDF you may want to lower the rpm (if you are restricted with the max speed) until the cut still looks good. You want to see shavings not dust coming out of the cut. This way you will greatly increase tool life.

examorph
28-01-2017, 10:44 AM
Thanks Paulus, I will try that.
Anyone got any advice on the aluminium parameters please? I understand that there are many variables that effect this but am just confirming figures roughly so that I dont snap the 2mm end mill within first 5 mins of cutting. Thanks.

Robin Hewitt
28-01-2017, 03:14 PM
MDF would usually be cut with a router bit because it is abrasive, aluminium alloy with a high helix milling cutter, pure aluminium is best cold formed because it really doesn't want to cut at all, horrible stuff. A stub cutter could go faster than a long series cutter so this is hard to guess. If you had it on the machining centre it is designed for then it would have a jet of coolant/lube on it keeping the cutter clear and cold. Without lube aluminium oxide will build up on the cutting edge which then ceases to be a cutting edge just before the tool breaks. I find surface finish is usually a bit naff from smaller cutters in aluminium but that could just be because I zoom in on the jolly old camera with small tooling. I need to guess a feed rate for a 2mm tool in aluminium alloy, I guess 1.5mm/s. :very_drunk:

JAZZCNC
29-01-2017, 10:20 AM
Thanks Paulus, I will try that.
Anyone got any advice on the aluminium parameters please? I understand that there are many variables that effect this but am just confirming figures roughly so that I dont snap the 2mm end mill within first 5 mins of cutting. Thanks.

Nobody can answer that question correctly because you don't give enough detail.
Even then with such small tools it can be lottery and you'll need to adjust on the fly while cutting. Coolant and good Chip clearing is MUST.

Honestly knowing you have only just got your machine working I think your being a little too ambitious trying to cut aluminium with small tool without any experience of machine or material.!! . . . Expect to break lots of tools.:hopelessness:

Tool length
Tool material
Tool Stickout
# of flutes
Material grade

examorph
29-01-2017, 12:54 PM
Nobody can answer that question correctly because you don't give enough detail.
Even then with such small tools it can be lottery and you'll need to adjust on the fly while cutting. Coolant and good Chip clearing is MUST.

Honestly knowing you have only just got your machine working I think your being a little too ambitious trying to cut aluminium with small tool without any experience of machine or material.!! . . . Expect to break lots of tools.:hopelessness:

Tool length
Tool material
Tool Stickout
# of flutes
Material grade

Cheers Dean, after doing the first cuts yesterday it did sort of click that I was trying to run before I could walk :confusion: For others, this is what 'cooked by end mill' MDF looks like :grey:
20521
It was just so tempting as I had the material and tools all at hand so thought why not :stupid:

The tools and details I am using are the following, all cheap eBay 2 flute cutters, aluminium grade either 5083 or 6082 as I could get either:
Cutting Pocket 1mm depth 40mm diameter - 6mm ball nose (50mm total length, Carbide tool, 20mm stick out)
Finishing 3D relief (1mm overall depth) after roughing with the 6mm ball nose - 2mm ball nose (50mm total length. Carbide tool, 14mm stick out)
VCarving text at depth of 0.35mm - 6mm 90 deg Spot Drill (67mm total length, HSS tool, 20mm stick out)
Profile part at 5mm depth - 8mm End Mill (61mm total length, HSS tool TiN Coated, 30mm stick out)

All tools got hot but the final profiling end mill was the one that got REALLY hot. Getting air connected will be easy enough as pipe, parts & 3 nozzles at spindle are setup but think I might have to start work on the mist setup sooner rather than later. Could I get away with air blast with manual spray of WD40 for now with smaller runs? Thanks.