[MACHINEFREAK]

Hello all,
I am drilling polycarbonate using a .027 dia. carbide drill in a Hydraulic holder, .530 Deep.
I am wanting the holes to have no internal burning.
I have used coolant , and moved to
Chilled air.
Any help on this would be GREAT!

[joeavaerage]

Hi,
polycarbonate is a s***t to machine, its so heat sensitive it gums up tools in no time.

You will have to peck drill, I would suggest 0.050 per peck or less with a full retract. Whether you use coolant or air, it has to dislodge the chips from the flutes of the drill
otherwise those chips will go back down into the hole and wreck things.

Craig

[ToolHIT]

Wow, .027" Diameter at .530" in Polycarbonate with no internal burning is not easy! Would you be using a Solid Carbide or Cobalt Drill right now? Carbide would be the way to go to reduce the heat if you can. I know there are options for coolant thru the shank to the tool, that would help reduce the heat generated and keep the internal burning from happening (if you would like info on this let me know).

Usually with Micro Drills we peck at 25%-50% of the tool diameter so I would try a peck of .007"-.014" and Craig is correct, you need a full retract or one within 0.5XD (.014") to make sure chips get out. If you are using carbide then RPM would be around 10,000 with a .0004"-.0008" IPR Freed Rate.

The chilled air makes a lot of sense and is really smarty, I just wonder if it would have the pressure to keep the part cool at .027" Diameter x .530" Depth. If not then the coolant thru the shank tool could be a good option.

Hopefully this helps!

Mike