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Pneumatic cylinders are fluid power devices
that use a compressed gas such as air to move a piston in a reciprocating,
up-and-down or back-and-forth linear motion. In double-acting cylinders (DAC),
pressure causes the piston to extend and then retract. In single-acting
cylinders (SAC), the compressed gas forces the piston in only one direction,
typically outward, and a spring provides the return motion.
Other air cylinder designs are available,
too, but all fluid power systems require proper maintenance for smooth
operation. In a Machinery Lubrication article called Why Air
Cylinders Fail, a pneumatics expert explains how "catastrophic failure can occur
when cylinder seals have insufficient lubrication." Although some industrial
buyers are now choosing so-called "non-lube" cylinders, seal failure remains a
concern.
If the walls of a pneumatic cylinder are too
smooth, there's higher adhesion friction between the O-rings and bore surfaces.
In addition, the absence of oil-retaining grooves can affect
lubrication. If the walls of a pneumatic cylinder are too rough, burrs and
other surface irregularities can shear softer seal materials such as rubber. If
seal failure occurs, pressure may be lost and air cylinder performance can
suffer.
Deburring
and Cylinder Surface Finishing
To protect the integrity of pneumatic systems,
manufacturers and maintenance personnel alike need to ensure that bores have a
proper surface finish. The Flex-Hone tool from Brush
Research Manufacturing (BRM) removes burrs and improves surface condition at
the same time. Suitable for any type or size cylinder, these flexible honing
tools also impart a series of oil-retaining grooves for optimum lubrication.
As BRM's Gold Booklet explains,
the Flex-Hone produces a crosshatch pattern of evenly-spaced "valleys". Flexible
cylinder hones also remove torn, cut, folded, and jagged metal while reducing raised
areas or "peaks" to a uniform height. With their distinctive abrasive globules,
BRM ball hones use a soft, low-temperature, low-pressure cutting action for
superior surface finishing and burr removal.
Flexible hones also feature a double-wire
metal stem for easy mounting in handheld power tools or production machinery.
As this YouTube video about ball
honing a pneumatic cylinder shows, use the Flex-Hone® with a good-quality
cutting fluid or honing oil. Because BRM ball honing tools are self-centering,
self-aligning to the bore, and self-compensating for wear, no special training
is required.
Rotate the
Tool or Rotate the Part
The Flex-Hone
Resource Guide provides information about tool selection as well as guidelines
for use. Although general speed ranges are given,
machine trials are required to verify parameters. In general, however, users
need to remember that flexible cylinder hones are low RPM tools, and that
revolutions per minute (RPM) is dependent upon tool diameter.
BRM cylinder hones should be
rotated prior to entering the cylinder, and should continue rotating until
fully removed from the part. Typically, users secure the Flex-Hone in a collet,
chuck, or similar holding device and then rotate the tool along with the
spindle. As this short YouTube video shows,
however, it's also possible to rotate the part instead.
By using flexible
honing tools, pneumatic cylinder manufacturers and plant maintenance personnel
can remove burrs, improve surface finish, and
promote optimum lubrication. Flex-Hone tools are proudly Made in the USA, and come
in a wide variety of abrasive types, grit sizes, and tool diameters for fluid
power and other commercial and industrial applications. For more information, visit the BRM website.
Author's Note: This CR4 blog entry originally appeared in the BRM
Flex-Hone Blog.
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