Stahlin Non-Metallic Enclosures
500 Maple Street
Belding, Michigan 48809
Phone: 616-794-0700
Fax: 616-794-3378
Email: [email protected]
Methods For Making Holes And Cutouts In
Non-Metallic Enclosures By Jeff Seagle Stahlin
Non-Metallic Enclosures
01/29/2009
Methods For Making Holes And Cutouts In Non-Metallic Enclosures By Jeff
Seagle Stahlin Non-Metallic Enclosures
Drilling of composite fiberglass material has been difficult and, for some, a
mystery. The ability to accurately drill holes in composite fiberglass material
has been the subject matter of numerous articles and how to demonstrations.
Composites offer the benefits of part integration and minimization along with
substantial savings in weight. Along with this is a reduction in the
requirements for machining operations that need to be performed to complete
an assembly. However all drilling and cutting operations can not be avoided
completely in most cases. There are several types of machining operations
that can be performed on composites such as turning, drilling, routing,
trimming, sanding, and milling. Most of these operations are similar to metal
removal techniques but there are some differences that need to be
addressed in order to make clean, high quality holes and cutouts in
composites.
Delaminating of the outer surface and glass fibers directly below the surface
are the main failure modes noticed when holes or cutouts are drilled or cutout
improperly. Most times excessive edge chipping around the perimeter of the
cutout or hole is due to improper tools used and methods applied. Other times
excessive fiber pulls or attached fibers not sheared off during the cutting or
turning process can also cause delamination failure from the tearing action
during material removal. Improper tools used and/or methods are also a
culprit of this failure mode. All these can lead to downstream assembly
problems, functionality problems, and become aesthetically unappealing if
taken to the extreme. The most common source of failure mode when making
holes in an enclosure is a dull cutting tool. Dull tools tend to rip or tear the
material rather than cutting or shearing the material and glass fibers. The
main culprit for tools becoming dull is glass fibers embedded in the material.
These glass fibers are very abrasive and can cause a tool to become dull
very quickly. A little planning and understanding of the proper methods to
machining composites up front can make all the difference in the final
outcome of the operation. Figure A shows delamination of the surface of the
part at the drill entrance. Figure B shows similar delamination just prior to drill
exit. 1.Hole Saw. The easiest and least complex method to provide an
opening in a composite enclosure is to use a fine-toothed hole saw. You must
first layout the size and location of the cutout, pre-drill a small hole in the
center within the cutout area for the hole saw to start, and then carefully cut
out the area to be removed. This is more time consuming and the least
accurate method but can be accomplished in almost any environment.
Keeping the saw perpendicular to the cutting surface, maintaining a
consistent sawing acting, and using a diamond impregnated hole saw or fine
toothed saw will provide the highest quality cutout with minimal edge chipping.
2.Drilling, Boring. Putting round holes in enclosure walls or thru the enclosure
door is the most common type of cutout used to provide entry into an
enclosure and access to the components housed within. The most common
tool used is the standard twist drill. A recommended tool would be a carbide
tipped or PCD diamond tipped tool that will maintain a sharp cutting edge.
HSS tools will also work but they will become dull very quickly resulting in
excessive edge chipping and a poor looking hole. We also recommend using
high RPM’s and low feed rates when using drills. This reduces the chipping
around the cutout. The single most important factor though is keeping a very
sharp tool.
Stahlin Non-Metallic Enclosures
500 Maple Street, Belding, Michigan 48809
Phone: 616-794-0700, Fax: 616-794-3378, Email: [email protected]
Stahlin Non-Metallic Enclosures
500 Maple Street
Belding, Michigan 48809
Phone: 616-794-0700
Fax: 616-794-3378
Email: [email protected]
Drill geometry and feed rates are the largest contributing factors when drilling
composites. Using a drill with a positive rake angle and thin points or split
points can help reduce cutting pressure and thus delamination at both
entrance and exit. Feed rates must also be constant and may even be
reduced upon exiting from a hole to reduce flexing of the part when the drill
exits. Using a solid back surface to support the part when drilling can also aid
in reducing delamination and chipping. 3.Routing. A third method is to use a
carbide router bit and router. This method produces very clean holes and
cutouts but also requires the holes and cutouts to be manually laid out
beforehand and a steady hand to stay within the layout lines. The use of a jig
or fixture to help guide the router is helpful to keep straight edges and clean
cutouts. The use of diamond impregnated router bits is preferred for longevity
but carbide bits will work just as well.
Jigsaws can also be used and are similar to routing of holes. Again, diamond
impregnated cutters are preferred but fine toothed cutters can also be used.
4.Punching. A fourth method is to use a standard hole punch similar to what
you would use with metal boxes. This produces a good clean hole but can
leave chipped edges if the punch is dull. Again maintaining sharp tools is
essential to producing clean cutouts. A pilot hole is required before using a
standard hole punch. Manual or hydraulic punch actuators can both be used
with composite materials. Punch press type manufacturing equipment can be
utilized if production volumes warrant. Proper support and sharp tools are
necessary to produce chip free, clean holes.
5.Alternative methods. Some additional methods that are sometimes used to
machine composites are water jet cutting and laser cutting. Both of these
methods will produce very accurate, clean holes or cutouts but also require a
high capital investment in both equipment and employee training. In water jet
cutting a high velocity stream of water and abrasive material is forced through
a small diameter (.010”) jet. The stream of water quickly erodes the material
with water pressure up to 60,000 psi and 2600 ft/s. Laser cutting uses a
concentrated raw light beam focused onto the part being cut. The cutting
operation takes place by local melting as in thermoplastics, vaporization, and
chemical degradation as in composites and thermosets.
For more information about Stahlin Non-Metallic Enclosures contact: Stahlin
Enclosures, 500 Maple Street, Belding, MI 48809 Phone:616-794-0700, Fax:
616-794-3378 Web: www.stahlin.com.
References: Sanjay K. Mazumdar, PhD Composites Manufacturing, CRC
Press, 2002
Stahlin Non-Metallic Enclosures
500 Maple Street, Belding, Michigan 48809
Phone: 616-794-0700, Fax: 616-794-3378, Email: [email protected]
Stahlin Non-Metallic Enclosures
500 Maple Street
Belding, Michigan 48809
Phone: 616-794-0700
Fax: 616-794-3378
Email: [email protected]
Drilling Holes in Stahlin's Composite Enclosures
Easy
(click or copy image for hi-resolution version)
Receive up-to-date information
by enrolling in our News
Program:
Have Questions? Request
information online.
Join Our RSS News Feed for
up-to-date information
When you subscribe to a
feed, it is added to the
Common Feed List. Updated
information from the feed is
automatically downloaded to
your computer and can be
viewed in Internet Explorer
and other programs.
Visit Yahoo to learn more
about RSS news feeds.
Click Here To: Subscribe to
OUR News feed
Stahlin Non-Metallic Enclosures
500 Maple Street, Belding, Michigan 48809
Phone: 616-794-0700, Fax: 616-794-3378, Email: [email protected]