Re: Plastic Drilling Question - Small Hole Process....

On Tue, 19 Aug 2008 15:51:29 -0400, "Joe AutoDrill"
<bob@xxxxxxxxxxxxxx> wrote:

I'm posting this here in case we have a plastic expert incognito.

I have a customer who bought a machine back in '05. Since day #1, they have
been trilling this material they call "Torlon PEI" with a. 0.029" drill at
around 10,000 RPM

The material is 3/8" thick and they have no problems making the hole itself.
I thought they would have to peck drill it, but apparently not...

The drill rapids up to the surface, takes a controlled feed rate from 1/16"
prior to the end of stroke (clean through) and retracts at rapid speed.
Much like a CNC would but with a simple, but highly controllable hydraulic
feed control doing the dirty work.

Now that every penny counts more, they found that the process leaves a burr
on the product that they have been removing since day #1 by hand. They want
to try and drill without getting that burr..

Here's the kicker... The burr is at the entry side, not the break through
side...

My first thought was that they were controlling the feed rate too late and
that the drill was entering the material fast, then slowing down and
completing the stroke. They claim that is not the case and that the feed is
100% controlled from entry to breakthrough. They also claim that the burr
shows up when entry happens and not during the process.

Anyone have any tips, thoughts or misc. ramblings on what might be causing
the problem?

RPM or other suggestions, thoughts? Etc... Can't really go above around
11-12,000 RPM on this application due to machine limitations.

My next suggestion to them was to try and get a small countersink bit but
they are using a drill bushing to make sure accuracy is held very tight.
Can't use a drill bushing in that case...

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R


** Posted from http://www.teranews.com **
Greetings Joe,
Since a drill bushing is being used how about grinding the end of the
drill bushing so that there is virtually no edge break, maybe .002",
on the exit end of the bushing. Then have the bushing contact the work
during the drilling process, or at least during the beginning, which
is when they say the burr is being formed. It seems to me that since a
drill bushing is being used for accuracy it must already be so close
to the work that the chips are going through the bushing. If this is
the case then having the bushing contact the work during the complete
drilling process would be fine and would prevent a burr from forming
at any time. I of course don't know what the setup looks like but
maybe a spring loaded drill bushing mounted in a ground sleeve would
make it easy to insure the bushing always contacted the work. The fit
between the bushing and sleeve could be kept to no more than .0002" so
accuracy would not suffer considering the holes are in plastic. If
space is limited belleville springs could be used.
Cheers,
Eric
.

Relevant Pages

  • Re: Plastic Drilling Question - Small Hole Process....
    ... 0.029" drill at around 10,000 RPM ... The drill rapids up to the surface, takes a controlled feed rate ... but highly controllable hydraulic feed control doing the ... leaves a burr on the product that they have been removing since ...
    (rec.crafts.metalworking)
  • Working in Plastic and Small Holes...
    ... I thought they would have to peck drill it, ... The drill rapids up to the surface, takes a controlled feed rate from 1/16" ... feed control doing the dirty work. ... Now that every penny counts more, they found that the process leaves a burr ...
    (rec.woodworking)
  • Plastic Drilling Question - Small Hole Process....
    ... I thought they would have to peck drill it, ... The drill rapids up to the surface, takes a controlled feed rate from 1/16" ... feed control doing the dirty work. ... Now that every penny counts more, they found that the process leaves a burr ...
    (rec.crafts.metalworking)
  • Small Hole in Torlon Material Having Problems...
    ... I thought they would have to peck drill it, ... The drill rapids up to the surface, takes a controlled feed rate from 1/16" ... feed control doing the dirty work. ... Now that every penny counts more, they found that the process leaves a burr ...
    (alt.machines.cnc)
  • Re: Working in Plastic and Small Holes...
    ... I thought they would have to peck drill it, ... feed control doing the dirty work. ... Now that every penny counts more, they found that the process leaves a burr ... Can't use a drill bushing in that case... ...
    (rec.woodworking)