BRM's Flexible Honing, Surface Finishing, and Deburring Blog Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog is the place for conversation and discussion about how to solve difficult finishing problems. For over 50 years, Brush Research Manufacturing (BRM) has helped customers use brushing technology to clean, rebuild, and resurface components ranging from engine cylinders to brake rotors to flywheels to firearms. BRM's Blog on CR4 provides real-world examples of how flex hones and wire brushes work. It also evaluates related technologies and invites questions from the community.

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Cylinder Honing: Tool Diameters and Operating Parameters

Posted April 22, 2014 4:19 PM by Brush Research

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.

Cylinder Hone Diameter

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 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.

Author's Note:

This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.


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