- Joined
- Dec 27, 2017
- Messages
- 340
So, I needed to machine out this piece of aluminum for part of the helicopter project. On hand I had an insert end mill that I got from eBay for the sole purpose of giving me some deep hole machining capability. The stick out needed to be 3" so the collet nut would not end up crashing into the top of the part.
Note: rpm was set to 3000 for both tests.
my first attempt was to use the entire depth of cut that the inserts could give me, which was about 0.350. Then I went down to a 0.100 width of cut and tried to run at 12 inches per minute. The results were not great and I was getting a lot of vibration. So I aborted the run and went back to the drawing board.
I knew the problem was that the mill was not liking that much sideload from a tool with that much stick out, so, the answer was to find a way to reduce the side load and increase the axial load (vertical load). I went from a 0.350 depth of cut, down to a 0.035 depth of cut. I increased the width of cut to 100% of tool width. I increased the feed rate to 60ipm.
metal removal with initial settings that gave me problems:
0.350 depth x 0.100 width x 12 feed = 0.42 ci/min
metal removal with modified settings:
0.035 depth x 0.875 width x 60 feed = 1.84 ci/min
The results were much better and although this is not really supposed to be the way to run an end mill, it's working well for my applications and that's all that matters. I had to push the mill to 60ipm to eliminate chatter. Once I did that, then it worked out ok. I used mist coolant and lots of it. The mix was Kool mist 77 with water. Spray mist had to be used because the inserts are not nearly as sharp as an end mill flute and chip weld would have been near-instant. I had my air gun handy and good thing too. It started to chatter when recutting chips, so I had to keep blowing the chips out of the hole every few seconds. Should have brought my snorkel gear along.
information on the end mill:
I got it from eBay from that Shars dealer located in Illinois:
I went with this end mill because it had a 3/4" shank, but the diameter of the actual cutter was 7/8". This would eliminate any chance of the tool rubbing on walls.
The only downside is that I found out I had to use their proprietary inserts which were not all bad because their prices were reasonable. I went with these inserts simply because that's what I could find on eBay, although I believe they have some that are actually intended for aluminum:
Note: rpm was set to 3000 for both tests.
my first attempt was to use the entire depth of cut that the inserts could give me, which was about 0.350. Then I went down to a 0.100 width of cut and tried to run at 12 inches per minute. The results were not great and I was getting a lot of vibration. So I aborted the run and went back to the drawing board.
I knew the problem was that the mill was not liking that much sideload from a tool with that much stick out, so, the answer was to find a way to reduce the side load and increase the axial load (vertical load). I went from a 0.350 depth of cut, down to a 0.035 depth of cut. I increased the width of cut to 100% of tool width. I increased the feed rate to 60ipm.
metal removal with initial settings that gave me problems:
0.350 depth x 0.100 width x 12 feed = 0.42 ci/min
metal removal with modified settings:
0.035 depth x 0.875 width x 60 feed = 1.84 ci/min
The results were much better and although this is not really supposed to be the way to run an end mill, it's working well for my applications and that's all that matters. I had to push the mill to 60ipm to eliminate chatter. Once I did that, then it worked out ok. I used mist coolant and lots of it. The mix was Kool mist 77 with water. Spray mist had to be used because the inserts are not nearly as sharp as an end mill flute and chip weld would have been near-instant. I had my air gun handy and good thing too. It started to chatter when recutting chips, so I had to keep blowing the chips out of the hole every few seconds. Should have brought my snorkel gear along.
information on the end mill:
I got it from eBay from that Shars dealer located in Illinois:
7/8x3/4x4.5" 90° Indexable End Mill APMT Insert 3FL W/Certificate P[ | eBay
Shim Screw M2.5 x 6.5 APMT 22 1003 PDER DM YBG202. RAMP MILLING, HELICAL INTERPOLATION MILLING. All types of square shoulder face milling, side milling and full slot milling (shaft end mill) of steels, alloyed steels, stainless and heat resistant steels, cast irons and aluminum alloys.
www.ebay.com
I went with this end mill because it had a 3/4" shank, but the diameter of the actual cutter was 7/8". This would eliminate any chance of the tool rubbing on walls.
The only downside is that I found out I had to use their proprietary inserts which were not all bad because their prices were reasonable. I went with these inserts simply because that's what I could find on eBay, although I believe they have some that are actually intended for aluminum:
ZCC 5PCS APMT 1003 22 PDER YBG202 CARBIDE INSERT FOR ALLOY STAINLESS STEEL !{ | eBay
SHARS APMT 22 PDER DM APMT 100308 PDER YBG202 FOR ALLOY STAINLESS STEEL. Insert Grade: YBG202. YBG202 Nano structure nc-TiAlN Coating Grade. Style: APMT. Nano structure nc-TiAln coating process ensures higher tenacity and hardness.
www.ebay.com
