I have often come to this sight for info. But there did not seem to be a lot here or on the web about drilling small holes, and small holes in aluminum in particular, when searching for information to help with a job we had.
So the job was drilling (3) 3/8 6061 aluminum plates to be used for a vacuum tool on a can depalletizer. Each plate was about 48" square and had around 2800 holes. The holes were drilled 9/32 (.281) .300 deep then drilled 1/32 the rest of the way through. The machine we were using was a Laguna CNC router. For tooling we used a 9/32 stub length carbide drill and a 1/32 HSS drill with bright finish and a fast spiral. From what I could gather the HSS with bright finish was better than coated.
To start with we used a standard spray mist coolant mixed strong. On the carbide drill, we ran about 10k rpm with a feed of .002 per tooth. There was not enough power and we stalled the drill in the fourth hole. But since there was lots of room cutting speed wise, we increased out rpm to 13k but kept the inches per min the same. This seemed to work fine. On the 1/32 drill we ran 20k rpm with a feed of .0005 per tooth. We cut about 100 holes before the first drill broke. The second drill only lasted about 30 holes. After pondering the problem we decided to switch from mist coolant to WD40. Seemed to solve the problem as we drilled the rest of the holes with the third drill. We the put that third drill and a drill we had used to drill 20 test holes under a microscope. That picture is included. It is not the clearest picture (we need to 3D print a camera to microscope adapter) but you can see a bit of dulling on the left hand drill (the one that drilled 2600 holes) but the flutes are clean and there is no build up. The one on the right has build up on the cutting edge and around the outside plus a chip stuck in the flute.
As a side note with the breaking the drills we ended up with around 10 holes that were not drilled (We did not drill them with the CNC as there was still broken drills stuck in 2 holes and the Laguna cnc control does not let you start in the middle of the program. Yes we could have written a small program to dill those few holes but it did not seem worth the effort). So we mounted a 1/32 drill in a right angle die grinder and drilled them with that. Seemed to work fine.
So the job was drilling (3) 3/8 6061 aluminum plates to be used for a vacuum tool on a can depalletizer. Each plate was about 48" square and had around 2800 holes. The holes were drilled 9/32 (.281) .300 deep then drilled 1/32 the rest of the way through. The machine we were using was a Laguna CNC router. For tooling we used a 9/32 stub length carbide drill and a 1/32 HSS drill with bright finish and a fast spiral. From what I could gather the HSS with bright finish was better than coated.
To start with we used a standard spray mist coolant mixed strong. On the carbide drill, we ran about 10k rpm with a feed of .002 per tooth. There was not enough power and we stalled the drill in the fourth hole. But since there was lots of room cutting speed wise, we increased out rpm to 13k but kept the inches per min the same. This seemed to work fine. On the 1/32 drill we ran 20k rpm with a feed of .0005 per tooth. We cut about 100 holes before the first drill broke. The second drill only lasted about 30 holes. After pondering the problem we decided to switch from mist coolant to WD40. Seemed to solve the problem as we drilled the rest of the holes with the third drill. We the put that third drill and a drill we had used to drill 20 test holes under a microscope. That picture is included. It is not the clearest picture (we need to 3D print a camera to microscope adapter) but you can see a bit of dulling on the left hand drill (the one that drilled 2600 holes) but the flutes are clean and there is no build up. The one on the right has build up on the cutting edge and around the outside plus a chip stuck in the flute.
As a side note with the breaking the drills we ended up with around 10 holes that were not drilled (We did not drill them with the CNC as there was still broken drills stuck in 2 holes and the Laguna cnc control does not let you start in the middle of the program. Yes we could have written a small program to dill those few holes but it did not seem worth the effort). So we mounted a 1/32 drill in a right angle die grinder and drilled them with that. Seemed to work fine.
