Manufacturers, machinists, and mechanics use medium-diameter Flex-Hone® tools to surface finish cylinders with bore diameters between 3” and 18”. These flexible cylinder hones from Brush Research Manufacturing (BRM) are grouped into GB, GBD, and GBD Wood Core categories, and specified by tool diameter, abrasive type, and grit size.
Medium-diameter cylinder hones are also designated as "standard duty" or "heavy duty", depending on the length of the abrasive part. Let's take a look at all of these parameters so that you can select the right Flex-Hone® tool for your medium-diameter application.
Tool Diameters
To produce a soft cutting action, BRM's flexible cylinder hones are always used in an oversized condition. This means that a Flex-Hone® for a 3” bore has a tool diameter that’s slightly greater than 3”. Tool diameter, along with application requirements, also determines operating parameters. Because smaller hones are used at higher RPMs, a 3” ball hone is used at a faster speed than an 8” ball hone. The Flex-Hone® Resource Guide provides suggested speed ranges, but it's important to perform your own machine trials, too.
Abrasive Types and Grit Sizes
All medium-diameter Flex-Hone® tools are available in seven standard abrasive types.
- silicon carbide (SC)
- aluminum oxide (AO)
- 25% zirconia / 75% alumina (Z25)
- 40% zirconia / 60% alumina (Z49)
- boron carbide (BC)
- tungsten carbide (WC)
- levigated alumina (LA)
The cylinder's base material determines which abrasive type to select. Grit size is determined by the amount of surface improvement that’s required. As a rule, it's best to start with a coarser-grit tool and then use a finer-grit tool. Grit sizes for medium-diameter ball hones range from 20 (coarse) to 800 (fine). The Flex-Hone® Resource Guide provides more information.
GB Series Flex-Hone® Tools
GB Series Flex-Hone® tools are medium-diameter cylinder hones for bores from 3-1/4” (83mm) to 4-5/8” (118mm). These flexible honing tools are described as "standard-duty" because they have a shorter abrasive length than GBD Series Flex-Hone® tools, which provide more abrasive per hone and typically last longer.
BRM supplies GB Flex-Hone® tools for five bore sizes: 3-1/4" (83mm), 3-1/2" (89mm), 3-3/4" (95mm), 4-1/8" (105mm), and 4-5/8" (118mm). The overall length (OAL) for all of these tools is 13-1/2” (342.9mm). Smaller GBD Series tools have this same OAL, but GBD Flex-Hone® tools for bores between 5" and 8" have an OAL of 17-1/2".
Automotive applications for GB Series Flex-Hone® tools include deglazing and finishing engine cylinders and cylinder liners. Industrial applications include any cylinder that requires deburring or surface finishing within the appropriate size range. Examples include pneumatic and hydraulic cylinders.
GBD Series Flex-Hone® Tools
GBD Series Flex-Hone® tools are medium-diameter cylinder hones for bores with diameters from 3” to 8”. These flexible hones are described as "heavy-duty" because they have a longer abrasive length than GB Series Flex-Hone® tools. In other words, GBD tools provide more abrasive per hone and typically last longer.
BRM supplies GBD Flex-Hone® tools for 14 different bore sizes. Smaller GBD tools for bores between 3” and 4-1/2” have an OAL of 13-1/2". Larger GBD tools for bores between 5” and 8” have an OAL of 17-1/2”. Compare this longer OAL to that of GB Series hones (13-1/2"), and to GBD Wood Core tools (34").
GBD Wood Core Flex-Hone® Tools
GBD Wood Core Flex-Hone® tools are medium-diameter cylinder hones built with an aluminum sleeve over a lightweight wooden core. BRM supplies these flexible honing tools for bores between 8" (203mm) and 18" (457mm).
All GBD Wood Core Flex-Hone® tools feature a steel hex drive shaft and have an OAL of 34". They are described as "heavy duty" because of their longer abrasive length.
Ready to Learn More?
Which type of medium-diameter Flex-Hone® tool do you need for your application? To learn more about how BRM’s flexible cylinder hones solve deburring, deglazing, edge blending, and surface finishing challenges, download the Flex-Hone® Resource Guide.
