CUTTING
COLD SAWING TURNED
INSIDE OUT A new way to look at cutting By Rich Marando
COLD sawing has been among the most
widely used methods for cutting tubes,
pipes, bars, and profiles for as long as
anyone can remember. The technology
has been anything but static. It has
evolved steadily over time through
advances in materials, coolants, coatings,
tooth forms, and cemented carbides.
At the same time, the materials used
for tubes, pipes, bars, and profiles have
been getting harder to cut. Any fabricator who has worked for years with
OCTG and precision mechanical pipe,
profile, and bar can attest to this.
Advances in metallurgical science and
process methods have allowed steel mills
to improve mechanical performance
characteristics dramatically and, in turn,
allow designers to reduce weight, size,
and cost of their end products.
In the world of circular sawing, it has
been a zero-sum gain: advances in cutting technology have been offset to a
large degree by the increasing demands
of cutting higher-grade materials.
However, a recent rethinking of machine
and blade design has updated this
technology, enabling it to take on these
new, hard-to-cut materials.
A circular saw blade that surrounds the tube and uses an oscillating motion eliminates the external burr and produces a negligible
internal burr.
A NEW PERSPECTIVE
ON CUTTING
A conventional cold saw blade is a circle
with the cutting teeth on the OD. It has a
hole at the center by which the blade is
affixed to the saw’s spindle.
A new blade design reverses that
arrangement. Called an ID ring saw, the
machine uses a circular blade that has
cutting surfaces on its ID. The main
spindle that rotates the blade engages
the blade at its OD. The machine feeds
the workpiece along the X axis through
the central void of the blade; the blade,
main bearing, and related drive system
are mounted on a Y-Z slide table that
oscillates the blade around the workpiece to make the cut.
This unconventional approach to saw
and blade design changed the way the
blade and workpiece interact, leading to
differences in most of the cutting characteristics—the allowable chip load, chip
size, chip shape, burrs, and noise.
Blade. Unlike a traditional circular
saw blade, the carbide elements are not
soldered to the blade; they are mounted
via machined seats and screws. The ring
saw uses off-the-shelf, milling-type
carbide inserts with four indexable
cutting edges. When one edge gets dull,
the saw operator rotates the insert to a
fresh edge. When all four cutting edges
have been used, the operator discards it
and installs a new one. This eliminates
the need to send the blade out for recon-
ditioning.
