Working With Aluminum #3

Clearing Chips with Air

 

  • Tool: Generic 2 flute 1/8" up spiral bits
  • Stock: 1/8" thick 6061 Aluminum
  • Lubrication: Trend Tool and Bit Cleaner

 

Clearing the chips becomes more important the deeper you cut. Take a 1/8" bit for instance cutting a part out of 1/2" stock. Its crucial that you get those chips out of the groove. If they build up things will go bad real fast. Most often they will weld them selves to the bit, then it will stop cutting and break.

If can battle this in two ways.

1. Lots of lube. This will create slurry that wont weld to the bit and most of it will just be thrown out by the up spiral bit.
2. Compressed Air. Blow the chips out.

I have a Kool Mist entry level blower/mister. I purchased it a few years ago for my CNC mini mill, but never used it. Its time to test it out. It has a magnet but I dont have anything on my Z-axis to stick it to. I took a piece of 2" angle and zip tied it to my spindle. This lets me slide the angle where I needed and the Kool Mist sticks to the angle just fine.

 

Here it is attached to my machine. Not quite permanent, but I can test things out.

The two tubes leaving the unit are for the compressed air and the coolant intake. For this test I wont be using any coolant, Just blowing air.

Once hooked to your compressor, you can dial in how much and where you want to blow the air. 

Now that we are blowing chips everywhere, we need a way to contain them. I built this little enclosure out of some scrap foam board and little angles I printed on my 3D printer.

Now that we are blowing chips everywhere, we need a way to contain them. I built this little enclosure out of some scrap foam board and little angles I printed on my 3D printer.

Here is the video of the blower in action. Note that I dont turn on the air until about 30 seconds in.
Still doing the same feeds and speeds as in the last test, but I did add a little pocket to the gear.

DOC: .01"
RPM: 24000
Cut Feed: 40IPM
Finish Feed 20IPM

Both cut and finish passes use a .25" ramp.

As you can see it really does clear the chips away. Note that if I was doing deeper cuts, I would probably be using a little longer bit, which would allow me to position the blower a little better.

 

Working With Aluminum #4

Misting

 

  • Tool: Generic 2 flute 1/8" up spiral bits
  • Stock: 1/8" thick 6061 Aluminum
  • Lubrication: Sta-Lub Soluble Oil

 


I have the Kool Mist hooked up, I might as well test the mister.

 

I attached a plastic container to the side of my monitor stand with zip ties, then added some Sta-Lube Soluble Oil and dropped the intake tube into the liquid.

 

Let's take a look.

DOC: .01"
RPM: 24000
Cut Feed: 40IPM
Finish Feed 20IPM

Both cut and finish passes use a .25" ramp.

 

The problem is when using the liquid, you cant turn up the air enough to evacuate all the chips or you will be spraying way too much lube. So while it worked very well at lubing the part and bit, I had a lot of chips. Probably would not be a huge problem but the less chips in the cutting area the better.

The optimum answer is to run two tubes, one for blowing the chips and the other for lube. Also controlling the mist via Mach3 could also allow you to spray some lube with every Z height change. 

Please note that I am nut using the mist as a coolant, but more as a lube. Even without any air or mist, the bit was staying very cool. My goal here is just to keep the aluminum chips from sticking to the bit.

With other metals its a completely different story.