Deep drilling aluminum


I was making something on the CNC mill last night. It is a little
block that I would clamp to the quill of the mill, so that I would
attach the Loc-Line coolant line to the quill. That way the coolant
would follow the cutting tool as the quill is raised or lowered.
Anyway, as part of that, I had to drill a deep hole (comparatively). I
used a peck drilling cycle and it worked, but took way too long, with
withdrawal of the tool and lowering it down, etc.
So I wanted to double check what is the recommended procedure for deep
drilling aluminum.
My feeling is that at the given RPM of 2400, I should have used a much
more aggressive feed rate than I used.
i
Reply to
Ignoramus4117
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From the OmniTurn users guide...
G83 Zn Kn Fn Rn Ln Cn
In G90, absolute mode: Z specifies the end of the point of the hole from the part Zero. In G91, incremental mode: Z specifies the distance the tool will travel from the starting point . Start location: Position the drill where you want the first drill peck to start. After the first peck the drill will rapid out to the R location, and then back to where it started less the C value. K specifies the depth of cut per peck. F is the drilling feedrate in inches per rev or minute depending on whether you are in G94 or G95. R is the retraction plane, the tool will rapid back to this location at the end of each peck. Default is the starting point of the cycle L is the rapid travel feed rate for the retraction move, noted in IPM. Default is 200ipm C is the clearance distance left when the drill returns to the cut. Default is .02?
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
Reply to
Gunner Asch
I have stuck and snapped a couple drill bits peck drilling aluminum with what I thought was very conservative feed and step depths.
Reply to
Bob La Londe
G83 is what I used too,
Yeah, I used this, it just took seemingly forever.
I will try to practice on a piece of junk tonight, with higher feedrates.
i
Reply to
Ignoramus4117
Did you use coolant?
The nice thing about peck drilling with coolant, is that the hole is completely filled with coolant.
i
Reply to
Ignoramus4117
Indeed. Probably the best for deep drilling aluminim. The long, wide flutes really get rid of the aluminum, particuarly with a good lubricating coolant.
Gunner
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
Reply to
Gunner Asch
nobody giving you numbers. I'd go 8 IPM and peck of .125 (1/2 D) if its a 1/4" drill. But I got dials to quickly change feed and speed, no doubt an adjust would be in order on part one. Don't consider me the definitive expert on speeds and feeds - I do it all by feel.
karl
Reply to
Karl Townsend
Karl, I mostly do it by feel too. I will get a piece of junk tonight and will practice somewhat if I have time. Thanks for the suggestion.
i
Reply to
Ignoramus4117
Too conservative can cause problems as well with not evacuating chips fast enough and resulting binding.
Reply to
Pete C.
Whats your max feed rate for retract? And what do you use for drilling feedrate? You can be fairly aggressive on aluminum.
And you can go fairly deep with each peck, particulary if you are using a nice sharp parabolic and coolant.
Gunner
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
Reply to
Gunner Asch
As a side note: If an exact precisely round hole is not absolutely required I've found that often it seems to work faster to use a slightly smaller end mill and make a round pocket rather than to "drill" a hole.
Reply to
Bob La Londe
If that is happening, you are not feeding fast enough. If you get aggressive, the chips will be a flying, not stringy.
Reply to
Cross-Slide
I do not have any cnc machines. But drilling aluminum on a regular drill press, I feed pretty hard and get a stringy chip coming out. When it get as long as I care to have it, I just hesitate on the feed for an instant. This causes the chip to break, and then I feed hard again so the new chip pushes the old chip out of the hole.
So you might try not actually pulling the bit out of the hole. Just stop feeding for about one revolution and then start feeding again.
On steel that does not make stringy chips, I peck and pull the bit out of the work so the chips get out of the hole.
Dan
Reply to
dcaster
Karl, what about this routine (with copious coolant): drill a small increment, then dwell the drill for a small fraction of a second to break chips, then continue. That would break chips, right? I could literally stop the Z axis movement to dwell for several times per second. Would that be enough? Withdrawing to SafeZ every time is very time consuming.
i
Reply to
Ignoramus4117
You want speed, right?
Gunner
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
Reply to
Gunner Asch

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