Any recommendations on bits and feeds/speeds to use for drilling holes (between 1/8" and 1/4" in diameter) in aluminum? My project involves drilling around 100 holes, so I’m looking for an efficient way to complete the task as well (so I’m preferring not to do it using inner contours). I’m using a VFD spindle.
Which specific alloy?
Does it work-harden?
There are two options here:
- a Drill toolpath (peck w/ full retract)
- use a tool at least slightly smaller than the hole and machine as a pocket
You may need coolant.
A single flute tool is probably a good idea, and a suitable coating should help.
There are specialty Drill-mills available, but note that a normal drill bit is not designed for usage at the speeds a spindle will spin at — do not use any tool at a speed faster than it can safely turn.
As Will says, it depends on the alloy, it will also depend on the depth you’re trying to drill.
I have a VFD spindle that I can run down to 2,500RPM if I need to with decent torque and have used 3mm and 4mm solid carbide drill bits with Isopropanol as lubricant for pre-drilling toolpaths which I then open up with a 1/8" end mill to get an accurate hole. With the pre-drill the boring toolpath can be much faster, but you do have to change tools.
If you’ve got an air spray or mist for coolant you may well do as well just running single flute coated end mills and boring the holes though.
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Also,
When running a boring toolpath on holes of this small a diameter, remember that the effective speed at the outside of the circle the machine is moving the cutter in is quite a bit faster than the CAM feedrate at the center of the cutter, it’s easy to end up killing the cutter with too high a feedrate.
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Thanks guys. I’m primarily working with C6063-t5 or C6063-t6 architectural aluminum or aluminum bronze 7387. I’m drilling through 1/8" square pipe.
I’ve got 274-Z 1/8" endmills, but I wasn’t sure if I would risk them using a drill toolpath.
If you’re drilling through both walls of the pipe at the same time then that will require good workholding and may be tricky.
On the toolpath, not sure if you’re using CC or something like Fusion but commonly a drill toolpath is a straight plunge of the cutter, which works for a drill but is not good for an end mill.
If you’re using end mills then you are far better off using an end mill that is smaller than the hole you require and running a boring toolpath which sweeps the cutter around the hole which both reduces the contact area and friction on the cutter and improves room for chip evacuation. I personally wouldn’t try to plunge a 1/8" cutter for a 1/8" hole.
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