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Drilling 6063: sudden problems, Speedio

gustafson

Diamond
Joined
Sep 4, 2002
Location
People's Republic
So as part of my work, for a very long time, I drill a lot of holes in 6063 extrusion. Drill tap #6
Suddenly after drilling, literally, millions of holes, I am dealing with drill breakage problems. Started with a new batch of a slightly heavier extrusion I run, but I moved onto a different job with a lighter extrusion that ran fine, ~5k holes no real issues.

Ran a job that I have run for, oh, 20 years, using the same extrusion from the same supplier the last 20 years. Same drill I have been using for 20 years[Guhring parabolic stub]. In the middle of a package of drills that I bought a year ago. Same coolant I have been using for 19 years[Blaser 2000CF]. Same program I have run in the same machine I have run them for the last year.

Machine: Brother Speedio S700 27K, 13 months old
Sk toolholder, no significant runout
Coolant 13 percent a bit rich but that ought to help
Feedrates 100 percent
Program is stored in machine, unchanged, feedrates consistent with every other program doing the same thing

Ran ~20-30 parts, broke a drill. OK, it happens, change drill
Breaks after 4 holes
OK
look at coolant, add some, its full, but clean screens and pressure seems better. Mentally compose post to 'check your Speedio coolant screens'
10 holes break drill
Swap in carbide drill I had been playing with on previous job[so maybe 50-100 holes]
12 holes, break drill
Swap back to previous. Change to brand new ER holder
2 holes break drill
Lower feed 40 percent, peck drill
5 holes break drill.

These are 9 dollar drills that usually last months, many thousands of holes.

Finally I go look up an old program and dial the spindle down from 20k to 5 and the feed down to what I ran on the old machine.

Run 100 parts

Now on these parts it is only costing me a couple seconds a part to slow down the spindle, but I run parts that have a lot more holes and it will add up.


Ideas?
 
Work holding? Or check material composition.
I run tons of Acetal rod and once in a while my optimum feed rates are not so optimum.
 
soft material

if you have some old stock that worked fine, mill couple clean 90 degree edges on both material samples and tap them against each other, compare dent depth, crude, but might be enough to test the theory
 
The first thing I would do is eyeball inspect each drill with a loupe. that would take perhaps 5 seconds per drill.
look to see the approximate clearance angle / drill point on center / that the clearance comes full up to the cutting edge.

Even a top drill manufacturer can make a poor batch of drills.
 
Check the R Plane in your program. I have seen instances where the X and Y would start to move before the tool was completely out of the hole. Especially on high response machines like a brother.
 
Check the R Plane in your program. I have seen instances where the X and Y would start to move before the tool was completely out of the hole. Especially on high response machines like a brother.
Again, same exact program stored in the machine since I ran them last
I run .1 above the surface
Tool breaks buried in the part
 
The first thing I would do is eyeball inspect each drill with a loupe. that would take perhaps 5 seconds per drill.
look to see the approximate clearance angle / drill point on center / that the clearance comes full up to the cutting edge.

Even a top drill manufacturer can make a poor batch of drills.
Middle of a package of drills
Changed to a totally different drill
Same thing
 
Could it be the specific batch of aluminum? All working great and all of a sudden it doesn't work has been my experience with 6063. I have ran enough of it in extruded box that I never minded it, but have a slight mishap and boom, spinwelding.
I guess I am trying to think of anything that isn't the material, because there is no fixing that. Dropped feed significantly same result. Generally one would think this would be in the details. I generally get many thousand holes out of a drill.
The saw didn't mind the extrusion and the blade is not as sharp as it could be
 
You likely just got a batch of extra gummy 6063 which is already softer than 6061 to begin with. I'd lower rpm and feed accordingly to avoid melting it to the drill which is likely what is happening. TSC would be optimal here but with the 27k I know that's not an option.
 
have you tried the same feed and speed in something more common like 6061 and to see if its the material? wondering if it didnt get hardened and its still in the as extruded state and got shipped out the door without it being T6
 
we have had more issues with material quality in the last 2 years than in the previous 20. Just an anecdote for your mental calculus
 
The number of busted tools and scrapped parts would probably pay for a simple metallurgical report on hardness (even a microhardness trace across a section) and composition, to rule material problems in or out.
 
My experience with 6063 is it ran fine as long as you got the coolant to the cut well. As soon as the coolant wasn't quite right, spinweld! With this in mind, I would say try to improve coolant delivery instead of slowing it down.

Any chance you can use 6061? As in getting a special run if it isn't available. That is what I did to solve my 6063 issues, which were mainly end use. The extrusion was 1"x3" 1/8" wall. Called our supplier up and they were fine running some 6061 through their dies, we just had to commit to the minimum run, which ended up saving money on the material.
 








 
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