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Looking at a job to drill 2 or 3 hundred holes .250 dia. and .086 dia. in type 66 nylon with 40% carbon fill. The depth is less then .250. I know this stuff is very abrasive. I would like recommendations for drill type, composition, and manufacturer if possible. Also suggestions for speeds and feeds would be great.
Vern
I would think a powdered metal or solid carbide would do the job with no problem, as far as speed goes start with the recomeded for aluminum and then add %30 and go from there. An air blast would be nice with small pecks to clear the chips, they are going to wrap up like crazy.
Live free or die
I have cut alot of carbon and here is what i would do.
the main enemy is heat. if you use a carbide tool and you can keep it cool you won't have any problems. I've used a cold air gun with great results. They coast about $300.00 bucks but when you can't use coolent it will save your butt!
Are you permitted to use water based coolant? If so I think you will be better off than with air. The cold air guns are a good alternative but the big compressor needed to run them is the expensive part.
Because you are not going deep I suggest trying it in one shot, fairly fast feed at two or three times what you would use for aluminum, dwell at the bottom for a few revolutions and then out.
Yes the chips are going to curl on the drill, they are going to curl anyway even if you peck. Doing it in a fast single shot means the chip is thick and rigid and there is a good chance it will fly off cleanly at the start of the next hole. Alternatively you might be able to fixture a stiff brush somewhere and run the drill past that in reverse to 'unscrew' the chip.
An open mind is a virtue...so long as all the common sense has not leaked out.
JROM
I've been reluctant to use coolant due to contaminating the sump/pump/lines. What has your experience been with plastic curls in the coolant sump? Where does one find a cold air gun?
Vern
Plastic chips in the coolant? Good question and a point I overlooked. We have fitted large water filters in our coolant system; right after the pump. Just regular domestic water filters.Originally Posted by Vern Smith
Before we did this on one machine Delrin chips clogged the coolant lines through the head and we hade to strip everything down to get them out. We tired blowing the blockage out and the mass of tightly compacte chips would slide one way until there was a constriction and stop; blow the opposite direction and they slid the other way and stopped.
By the time that machine was all sorted out the filters had been installed on all the other machines and we have not had any problems since. Filters typically last 3 months.
Regarding the air gun I think if you Google Vortex Air Gun or Cold Air Gun you should find something.
An open mind is a virtue...so long as all the common sense has not leaked out.
The last CNC based shop I worked in we occasionally ran Glass filled nylon, which I assume is the same thing. We used the regular old air nozzle that we rigged up for blowing the chips off. But we were surfacing cutting so it was alittle different application.
On the TM that in the hop I'm working now, I tried running and acrylic job with coolant and it work really well, but at the time hadn't really thought much about getting chips in the sump. Well it turned out when I got the job done, I had a huge amount of chips that washed into the unit. The factory screen kept most of the chips from migrating elsewhere. But I didn't feel comfortable relying on just that. so being a bit thrifty, I bent up a screen holder and placed some very fine mesh stainless screen in the holder. It fits into the sump opening and collects the chips before ever getting into the main part of the resavoir.
The Vortex gun is a good option, I think they can be a bit loud, never used one. But I know companies like MSC have them in their catalog.
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