Machining Fundamentals 166
teeth too fi ne will clog (load) and jam, causing the
teeth to shear off. A blade that is too coarse (less than
three teeth cutting) will cause the same problem.
Make sure the blade is properly mounted and cut-
ting on the power stroke.
11.5 Metal-Cutting Circular Saws
Metal-cutting circular saws are found in many
areas of metalworking. Primarily production machines,
these saws are divided into the following three
classifi cations:
• Abrasive cutoff saw.
• Cold circular saw.
• Friction saw.
An
abrasive cutoff
saw, Figure 11-17, cuts mate-
rial using a rapidly revolving, thin abrasive wheel.
Most materials—glass, ceramics, and metals—can be
cut to close tolerances. Hardened steel does not require
annealing to be cut. Special heat-resistant abrasive
wheels are available for high-speed cutoff of hot stock.
Abrasive cutting falls into two classifi cations,
dry and wet. Wet abrasive cutting, while not quite as
rapid as dry cutting in some applications, produces
a fi ner surface fi nish and permits cutting to close tol-
erances. The cuts are burn-free and have few or no
burrs. Dry abrasive cutting does not use a coolant
and is used for rapid, less-critical cutting.
A
cold circular
saw, Figure 11-18, makes use of
a circular, toothed blade capable of producing very
accurate cuts. Large cold circular saws can sever
round metal stock up to 27″ (675 mm) in diameter.
A
friction saw
operates at very high speeds
(20,000 surface feet per minute or 6000 meters per
minute) and actually melts its way through the metal.
The friction saw blade may or may not have teeth.
Photo courtesy of Weiler Corporation
Figure 11-17. An industrial abrasive cutoff saw.
A
B
W.J. Savage Co.
Figure 11-18. Cold circular saws. A—This automated cold
circular saw can accept a piece up to 2500 pounds. A laser
guide light marks the position of the cut. B—This machine
can be fitted with carbide-tipped blades or abrasive disks.