Flex Zone Guide
How to Select the Right Flex-Hone
Step 1: Measure Your Bore
Use a bore gauge or inside micrometer to accurately measure the cylinder bore diameter. Flex-Hone tools are sized to fit specific diameter ranges.
Always measure at multiple points to account for wear or taper in the bore.
Step 2: Choose Series
BC Series (4mm-3"): Standard duty for small applications such as brake cylinders, valve guides, boiler tubes
GB Series (3-1/4"-4-5/8"): Standard duty for most automotive cylinders, hydraulic cylinders, and general applications
GBD Series (3"-8"): Heavy duty for automotive and hydraulic cylinders and larger applications
GBD Series (8"-18"): Heavy duty with separate core and shaft, used for large cylinders
Step 3: Select Grit Size
Grit selection depends on your desired surface finish and the current condition of the bore.
Standard Flex-Hone Sizes & Grits
The standard Flex-Hone range is made from Silicon Carbide abrasive and comes in diameters ranging from very small 4mm to very large 475mm (18"). Aluminium Oxide abrasive is also generally available in Flex-Hones in a range of diameters to suit small tube up to 100mm for engine cylinders.
The main abrasive grit sizes are 180 grit (medium) and 240 grit (medium fine). Specified grit sizes in Flex-Hones are not at all similar to grit sizes in other grinding media such as grinding wheels or abrasive cloth or paper. For instance a surface finished with a 180 grit Flex-Hone would produce very much finer surface patterns than a 180 grit sheet of cloth abrasive. Flex-Hone finish can also be varied by using different weights of lubricant during honing. For instance grease smeared in a cylinder bore before Flex-Honing will produce a finer cut than oil. Other grit sizes generally available in Flex-Hones are 120 grit (coarse), 320 grit (fine) and 400 grit (extra fine).
Factory Special Flex-Hones
Flex-Hones can be made to order for special applications. Possibilities include grit sizes from 20 grit to 800 grit and very large diameters up to 900mm (36"). Factory specials are also available in non standard abrasives such as Boron Carbide, Tungsten Carbide, Alumina Zirconia, Levigated Alumina, Diamond and CBN.
Selecting Correct Grit Size for a Flex-Hone
The grit size required for a particular job will be determined by a number of factors. These factors include such things as the type of material being honed, the type of engine rings or hydraulic seals used and the grade of lubricant used in service in the engine or machine. As explained above choice of cutting lubricant used during the honing process also affects finish and grit selection. If finish is critical, the only conclusive way to establish the best grit size for an application is by conducting tests on the actual job. Probably 99% of general applications produce a very satisfactory finish using either 180 grit or 240 grit coupled with variations of cutting lubricant. Coarser and finer grits can increase the cost of the tool substantially so they are generally reserved for special and critical applications.
Operating Instructions
- • The Flex-Hone can be used in a variety of rotating spindles from CNC equipment to a portable hand drill. Do not use air tools or high speed drill motors.
- • Ensure the tool is securely held in a collet, chuck or similar holding device.
- • The tool should be well coated with lubricant. Use a 10-30 weight or Flex-Hone Oil, except when honing hydraulic brake cylinders. When honing hydraulic brake cylinders use the hydraulic brake fluid as a honing lubricant.
- • Run the Flex-Hone Tool rotating upon entry and removal from the cylinder.
- • Refer to table on RPM & Surface Finish page for recommended RPM range.
- • Use 60-120 strokes per minute depending on RPM.
- • Honing time should be approximately 20-45 seconds per cylinder.
- • DO NOT use solvents such as kerosene for honing or cleaning.
- • Clean cylinders after honing with warm or hot water and detergent using a brush, and then oil the cylinder.
Need Help Selecting?
Contact our team for assistance choosing the right Flex-Hone size and grit for your application.
Need Help Choosing the Right Flex-Hone?
Contact our technical team for expert advice on Flex-Hone sizing and grit selection for your specific application.