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Author Topic: This cut is as bad as it gets  (Read 3460 times)

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This cut is as bad as it gets
« on: May 19, 2015, 03:45:03 PM »
I could use some help sorting this out. Please don't ridicule me at the poor state of this test cut, I really want to get this right.

Details as follows.
6mm 3 flute cutter running at 2100rpm
Feed rate is 250mm per minute
Pass depth of cut 1/2mm
Coolant used is 'Parafin' misting.

So why all the burring ???

I ran a file across the top of the job for the second picture.

Any helpers

George

« Last Edit: May 19, 2015, 03:54:43 PM by Len-Tikular »
One step at a time!

Offline SSPW

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Re: This cut is as bad as it gets
« Reply #1 on: May 19, 2015, 04:05:28 PM »
Not being insulting, cause i have done if before, and the resulting mess kinda looked like that.

Is the spindle turning the correct direction?
Re: This cut is as bad as it gets
« Reply #2 on: May 19, 2015, 05:16:45 PM »
That's a jolly good question.
I never considered that. I'm assuming it's turned in the same direction as it always did. It's a 240Vac motor driven spindle.

George
One step at a time!
Re: This cut is as bad as it gets
« Reply #3 on: May 19, 2015, 05:43:08 PM »
Couple of quick points.
It looks to be a 3 Series Aluminum(very soft and Malleable), and this is quite common with that grade of Aluminum.
You need to Check your Speed and Feeds(look at chip tooth loading and depth of cuts),
however I think Climb Milling may get rid of the Chip extrusion, provided you clear the chip
 path by using a brush or Air between each Cut. If you can try hooking up a blast misting arrangement, it will clear the
chips and lubricate and cool at the same time.
Wes
Re: This cut is as bad as it gets
« Reply #4 on: May 19, 2015, 05:51:27 PM »
Just some quick Calcs
6mm 3 flute end mill in Aluminium. 0.5mm cut depth Conventional Milling
RPM = 7855
Feedrate = 298mm/min
Fine Finish
HSS Tool
Roughing
RPM =9240
Feedrate =1600mm/min
Re: This cut is as bad as it gets
« Reply #5 on: May 20, 2015, 03:49:33 AM »
Thanks Wes,

Maximum spindle speed is 2100rpm

I was climb milling this part and was Misting using a parafin mister. I was clearing the chips away with a brush,

I'll try 'Conventional milling' next. and double the feed to 20 inches per minute.

George
One step at a time!

Offline Hood

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Re: This cut is as bad as it gets
« Reply #6 on: May 20, 2015, 05:01:15 AM »
What grade Alu?
Was it a sharp cutter? Blunt cutters will throw up a burr.
0.5mm DOC is not very much. Personally I would be looking at 2mm as a minimum but maybe your machine is not rigid enough for more?

Hood
Re: This cut is as bad as it gets
« Reply #7 on: May 20, 2015, 05:19:57 AM »
What helix angle tool  are you using?
Re: This cut is as bad as it gets
« Reply #8 on: May 20, 2015, 06:37:02 AM »
I was a bit reluctant with any more than 0.5 depth of cut. I really would like to cut at 2mm per pass as otherwise it takes ages. But then again its not a race!
The mill is a bench mill but I thought it would be rigid enough for what I'm doing. ?
Perhaps my cutter wasn't the sharpest, I will give 2mm a test when I buy myself some new 2 flute hi helix cutters.
As for the material, I'm unsure. It came from the junk box.
Looks like I have a lot to learn!!

I appreciate all comments.

George
One step at a time!
Re: This cut is as bad as it gets
« Reply #9 on: May 20, 2015, 03:08:38 PM »
Just throwing this out there...

Your cut looks like the cut I was getting when my supplier mistakenly gave me 5052 alloy aluminum sheet rather than the 6061 T6 alloy I ordered. I was new to cutting aluminum, so for 2 days I was trying to figure out what I was doing wrong. I finally figured out it was the material, not my bit, speeds, & feeds.

Chris