A Practical Operating Guide for Fluid Power Machining

Flexible ball hones—also known as Flex-Hones, ball hones, or cylinder hones—are versatile tools for deburring, surface finishing, and plateau honing in hydraulic and pneumatic components. However, achieving consistent results requires correct operating parameters. Using the wrong RPM, feed speed, or lubricant can damage the tool, scratch precision bores, or produce an inferior surface finish.

This guide provides recommended operating parameters for flexible ball hones on hydraulic and pneumatic components, including cylinder tubes, valve bodies, pump housings, and manifolds.

1. RPM Selection

The flexible ball hone is a low RPM tool. RPM varies with tool diameter—smaller diameters require higher spindle speeds, while larger diameters run at slower speeds.

General rule: Start with a spindle speed between 500 and 800 RPM. Never exceed 1,200 RPM. Reduce speed on entry and exit to avoid oscillation that could compromise the shank.

For hydraulic cylinder honing with a portable drill: 400–600 RPM is a typical starting point.

2. Feed Speed (Stroke Rate)

Stroke rate determines the cross-hatch angle. For a 45° cross-hatch angle—the industry standard for oil retention and seal performance—use the following guidelines:

Feed rate note: Some manufacturers specify a general feed rate of 150 – 250 IPM for standard applications.

Important: Smaller-diameter tools require faster stroke rates to achieve the same cross-hatch angle as larger-diameter tools.

3. Honing Time and Stroke Count

Critical: Do not over-hone. Too much honing can result in removal of material and alter bore geometry.

4. Coolant and Lubrication

The #1 Rule: Never Hone Dry

Flex-Hone® tools always require the use of a lubricant. Operating the tool dry will:

• Load the tool with abrasive material and metal debris

• Cause debris to become embedded in the workpiece

• Generate excessive heat and shorten tool life

Recommended Lubricants

Lubricants to Avoid

Lubrication Best Practices

5. Dry vs. Wet Honing

Wet honing is required. Dry honing is not recommended as it significantly reduces tool lifespan. The lubricant serves three critical functions:

1. Heat management – Keeps heat to a minimum

2. Tool loading prevention – Prevents the tool from loading with abrasive material and cast-off metal

3. Debris suspension – Suspends the material being removed

6. Quick Reference Summary

7. Critical Operating Rules

1. Always lubricate – The tool requires lubricant at all times

2. Rotate before entry – Start the tool spinning before entering the bore

3. Enter and exit while spinning – Remove the tool while it's still rotating

4. Do not change direction inside the bore – Avoid reversing rotation while inside the workpiece

5. Reduce speed on entry and exit – Prevents oscillation that could compromise the shank

6. Never exceed 1,200 RPM – The flex hone is a low RPM tool

7. Do not use air tools or high-speed motors – Not suitable for flex hone operation

8. Clean thoroughly after honing – Use warm water and detergent, then oil to prevent corrosion

8. Preventing Scratches on Precision Bores

To avoid scratching precision hydraulic and pneumatic bores:

• Always use lubricant – Dry operation embeds debris in the workpiece

• Use the correct RPM – Excessive speed generates heat and can cause smearing

• Maintain consistent stroke rate – Prevents irregular cross-hatch patterns

• Clean the tool before use – Remove any debris from previous operations

• Never use solvents – They degrade the tool and can leave residue

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