Brush
Research Manufacturing (BRM) supplies flexible cylinder honing tools
for bores with diameters as small as 4mm and as large as 36”. A flexible,
resilient honing tool, the Flex-Hone® is
self-centering, self-aligning to the bore, and self-compensating for wear. Flexible
hones improve surface finish and remove burrs at the same time, and can be used
in either handheld power tools or machine centers. Known also as ball hones, these brushing
tools feature abrasive globules permanently laminated to flexible nylon
filaments.
To
produce a soft cutting action, Flex-Hone® tools are always used in an oversized
condition. This means that a deburring tool for a 3” bore, although listed as a
3” tool, has a tool diameter that’s slightly larger than 3”. On the BRM website,
cylinder hones are categorized as standard small-diameter (4mm to 3”), standard
and heavy-duty (3” to 18”), and super heavy-duty large-diameter (19” to 36”). Diamond Flex-Hone® tools
are available in 4mm to 1-1/2” diameters and Flex-Hone® for chamfer blending tools
come in 4mm to 7/8” diameters.
Rotational Speed
Diameter
is an important specification to consider not just during brush tool selection,
but also during Flex-Hone® use. Ball hone size helps determine the recommended
operating speed in revolutions per minute (RPM). The Flex-Hone®
Resource Guide provides some general ranges for rotational speeds, but
users should perform machine trials to test their own equipment against these
guidelines. In general, however, larger tools run at slower speeds and smaller
tools run at faster speeds.
Stroke Rate
Tool diameter also drives another important
operating parameter: stroke rate. This is the number of inches per minute (IPM)
that are fed or stroked during flexible honing operations. Depending on how the Flex-Hone® tool is
configured, stroke rate is controlled either by machine parameters or by a
human operator. Stroke rate is also related to the angle of the cross-hatching
on cylinder walls, the tiny oil-retaining grooves that help optimize lubrication.
Cross-Hatch
Angle
Flex-Hone® tools improve cylinder wall surface
quality by imparting a cross-hatch pattern and producing a plateau finish. The angle at which these cross-hatched
lines intersect can vary, and is a function of both stroke rate and rotational
speed. As the Flex-Hone® Resource Guide advises, use a slower stroke rate to achieve
a smaller cross-hatch angle (e.g, 20° to 23°). Use a faster stroke
rate to achieve a larger cross-hatch angle (e.g., 45°).
Putting It All Together
Tool diameter helps determine the recommended speed,
and is related both to stroke rate and cross-hatch angle. Remember, however,
that smaller-diameter Flex-Hone® tools
require faster stroke rates to achieve the same cross-hatch angle as
larger-diameter tools.
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