ROUTING: Router Bits for the Sign Industry
Signs and the information they convey have become
an integral part of daily life. Companies of various
sizes serve this vast market but they all have common
problems when it comes to routing the materials common
to the industry. Wood, aluminum, foam and plastic all
have different cutting characteristics and no individual tool
can solve all routing problems. This is particularly evident in
the routing of plastics in the sign industry.
As a starting point, plastics can be
placed into two general categories:
flexible and rigid. The tools of choice
for flexible plastic usually involve the
use of single or double edge “O” flute
tools, which are available in straight
or spiral flute configurations. In terms
of rigid plastics, double edge straight
“V” flute tools, spiral “O” flutes with
hard plastic geometry, and two and
three flute finishers are recommended.
The tool materials for most of
these router bits are readily available
in high-speed steel for hand operations
and solid carbide for CNC routing.
Solid carbide is a very durable
material when utilized in a controlled
environment of CNC, but not reliable
in hand routing, which tends to be
less rigid with more opportunity for
These recommendations are general
in nature and are just a beginning
for tool selection. In order to target
an application, the sign maker has a
new resource on the Internet at
www.plasticrouting.com. This site
provides a specific tool recommendation
for a variety of plastic materials.
The major emphasis of this website is
to recommend router tools that provide
the best finish at a productive feed rate. Sign makers,
who historically use smaller diameter tools to achieve the
necessary radii associated with lettering, will be pleasantly
surprised. The tool diameter is the controlling factor in
feed rate, but larger diameters were not necessarily superior
in terms of finish. The use of micro grain carbide with
the necessary geometry to achieve chip evacuation has
made smaller diameter tools more effective for the industry. The site can also be accessed via a link on IAPD’s
web site at www.iapd.org.
Recently, there have been several new
styles of specialty tools developed to
improve finishes with faster cycle times without
tool changes and/or
advanced programming techniques.
Both should prove to be
advantageous to the sign industry.
The first was developed to
provide a smooth bottom surface
in lettering or pocketing
applications. Most router tools
are designed to plunge and rout
with the emphasis on the side
geometry rather than the point.
Consequently, the point end
would always leave swirl marks,
which required a secondary
operation to remove the swirls.
The new tool (Figure 1) utilizes a
near flat point with radiused
corners to create a smooth bottom
The second innovation (Figure 2) is the development of
a rout and chamfer bit designed for plastic sheets. By
combining both a straight flute optimized for cutting plastics
with a cutting edge sized for specific sheet sizes and a
45 degree chamfer edge, these tools can rout out plastic
parts and apply a variable depth edge chamfer in a single
pass. By combining these features into a single tool, tool
changes within the machining cycle are eliminated and
CNC routers without tool changing spindles have new
capabilities for parts production.
The advances in router tooling have generally followed
the rapid growth and usage of CNC routers or router
tables as they are commonly called in the sign industry.
These machines have revolutionized the speed and accuracy
of sign making and the ability to produce intricate
shapes and designs with specialized software. Router tooling
has enhanced the CNC user by providing stronger
tools with improved cutting geometry specific to the material
being machined. However, merely choosing the correct
tool without effective machining practices is an exercise in
futility. Consequently, a review of proper machining practices
would be in order:
The right tool for the job and sound
CNC machining practices will improve
throughput, product quality
and profitability in the sign industry.
- Maintain CNC machines per manufacturer’s recommendation
with proper lubrication of machine slides and
- Check for play in the table or spindle mounting systems.
Establish a collet, collet nut and tool holder maintenance
program and replace collets
after 600-700 hours of usage.
- Insure part rigidity by following
proper spoilboard technique.
- Establish colleting procedures to
maximize tool rigidity.
- Maximize chipload to minimize
- Select tools with the shortest possible
cutting edge length to achieve
depth of cut.
- Use straight through tools where
the cutting edge length and shank
are the same size to reduce breakage.
- Maximize dust collection to completely
evacuate gummy chips produced
by some plastics.
For more information, click on the author biography at the top of this page.