Drill bit question 1

[jvo1]

Just a simple question:

Whats the best drill bit for drilling 6061 T6 aluminum with the highest accuracy? (what kind, tip, etc)

I've designed a tooling fixture to do some operations in-house to save money and by having an accurate bit, will also save steps. Any suggestions are appreciated, thanks.

 

[jvo1]

Oh yes, and long life for the bit is also a must.

 

[BillPSU]

What kind of machine?
What kind of coolant?
What type of tooling? Drill jig or holding fixture?
What tolerance is hole?

 

[scottmaha]

Taking in to account that you have a rigid setup, coolant throught the spindle, and an accurate tool holder (ER collet or hydraulic chuck), then I would go with the "G" drill. This is a double margin straight flute drill that is designed for drilling and reaming in one pass. I would not look to hold a much better tolerance than +/-.0005" with this drill though. Because of the straight flute design, you really need coolant through the tool to help expedite the chips from the hole. We use the RT150GG from Guhring. They make the drill standard in 4, 7, and 10 x D. If you do not have coolant through the tool capability and you are drilling less than 5 x D, then I would go with the spral flute, three flute drill from Guhring. It is their series #5518 with GS200G point. The point is helical for accurate location and the flutes are polished for aluminum.

Hope this helps.

 

[jvo1]

Thank you!

 

[jvo1]

Let me be a bit more specific in case anyone can offer more advice...

This will be done on a mill, through a drill bushing, clamped down in a fixture, through .25" 6061 T6 Alum material, with a .375" drill +/- .001 at worst, manually added oil.

 

[BillPSU]

Combination drill reamer would be my choice. Bushing will guide on reamer O.D. I would set it up with mist coolant to avoid galling. Manually added oil may prove troublesome.