Hello Joe;
I'm glad to help! I'm a veteran mechanical engineer, machinist, and
fabricator, as well as a woodworker, so I'm quite familiar with the
types of machines that you offer.
One of the bigger manufacturers of MDF is Sierra Pine
(
www.sierrapine.com). Check out their website for technical info on the
various grades of MDF.
In my shop, I mostly use MDF for templates, fixtures and light duty
tooling. Sierra Pine's "standard" MDF, which weighs 48 lbs/cu.ft., is
my favorite. It drills and machines beautifully. The various Lite
grades, at around 30-35 lbs/cu.ft. are much more difficult to work
with. The low-emission Lite grade is the worst for drilling. There
seems to be so little resin holding the core together, that as soon as
you pierce the skin, it's like drilling a stack of newspaper. But the
low-emission lite grades are popular with furniture factories because
of the lighter product weight and reduced employee health hazards. So,
that's probably what many of your customers are using.
I would guess that the solution to production drilling it is mostly in
the fixturing. The key would be to tightly clamp the MDF between two
flat-faced drill guide bushings, to prevent the surface skins on either
side from flaring, which then allows the inner layers to rip. A brad
point or even a reverse-ground drill bit would probably be the best,
with a fast spiral and very sharp outer flutes. If the MDF is properly
clamped and supported, you can probably run a very fast feed profile.
The trick will be in clearing the swarf out of the drill bit and the
bushings.
Bruce Johnson
Johnson's Extremely Strange Musical Instrument Co.
Burbank, CA