RPM for mounted tools

Understanding the RPM for mounted tools and consumables is crucial when surface finishing. We are regularly asked what RPM our customers should be running their mounted tools and consumables at. Of course, the answer is very dependent on the surface finish you are trying to achieve, the equipment you are using and the consumable itself. However, we wanted to put together some basic guidelines to help you get started. These are simply guidelines, and for more expertise give us a call – we can understand your exact application and provide the formula to get you a consistent surface finish which achieves the RA value you are striving for.

In this blog we also detail why understanding surface speed is so critical, if you are using different sized diameter consumables on the same workpiece.

Why is RPM so important when surface finishing?

The RPM (Revolutions Per Minute) of your consumable is critically important in surface finishing for several key reasons:

Material Removal Rate: The RPM directly impacts the rate at which material is removed from the workpiece. Controlling the RPM allows you to adjust the aggressiveness of the finishing process. Higher RPMs generally result in faster material removal, while lower RPMs are more suitable for precision work with minimal material removal.

Surface Finish Quality: The RPM significantly influences the quality of the surface finish. Higher RPMs can create a smoother and finer finish by generating more consistent abrasion or polishing actions. Conversely, lower RPMs can help achieve a coarser finish or remove imperfections with greater control.

Heat Generation: The RPM affects the heat generated during surface finishing, especially in processes like grinding. Higher RPMs can generate more heat, which may lead to thermal damage or distortion of the workpiece. Lower RPMs can help manage and reduce heat generation.

Tool and Consumable Life: Running consumables at the correct RPM ensures that they wear evenly and last longer. Operating outside the recommended RPM range can lead to premature wear and reduce the effectiveness of the consumables.

Safety: Operating consumables at the appropriate RPM range is essential for safety. Excessive RPM can lead to equipment failure, accidents, or injury, while RPMs that are too low may result in inefficient operation.

Efficiency: Correct RPM settings make the finishing process more efficient. It ensures that the consumables are performing optimally, reducing the need for rework and saving time and resources.

Consistency: Maintaining a consistent RPM throughout the finishing process is crucial to achieve uniform and consistent results across the entire workpiece. Variations in RPM can lead to uneven finishes, streaks, or other defects.

Material Compatibility: Different materials have varying optimal RPM ranges for finishing. Operating within the recommended RPM range helps ensure compatibility and effectiveness for the specific material being processed.

Surface Integrity: Proper RPM selection can prevent material deformation, work hardening, or stress buildup during finishing, preserving the integrity of the workpiece’s surface.

Cost-Effectiveness: By running consumables at the correct RPM, you can optimize the process, reduce waste, and achieve the desired finish with minimal waste of materials, consumables, and energy.

General guidelines for RPM on Mounted tools and consumables

Note that these are very general guidelines and please refer to the manufacturers guidelines. Also, to note that RPM will depend on the desired finish and the material you are working with

RODA Range

• 30mm RODA Nywheels are typically run between 16,000 and 22,000 RPM – for other sizes give us a call.
• RODA Point at approx 10mm diameter these are typically run at between 20,000 and 22,000 RPM – for other sizes give us a call.
• RODA Felt – when working with a felt bob at around 10mm diameter the RPM should be approx 12,000 – 16,000 RPM – for other sizes give us a call.

Mounted Points:

• For precision grinding and small material removal tasks, mounted points are typically run at higher RPMs, often in the range of 20,000 to 40,000 RPM.
• Coarser grits and harder materials may allow for higher RPMs, while finer grits and softer materials may require lower RPMs.
• Follow the manufacturer’s recommendations and guidelines for the specific mounted points you are using.

Mounted Brushes:

• The recommended RPM for mounted brushes can vary depending on the type of brush (e.g., wire brush, abrasive brush) and the application.
• Wire brushes may run at higher RPMs for aggressive cleaning or deburring, while abrasive brushes may require lower RPMs for finer surface finishing.
• Refer to the manufacturer’s specifications for the specific type of mounted brush you are using.

Rubber and Polishing Points:

• Rubber and polishing points are often used for smoothing and polishing applications and typically run at lower RPMs.
• The recommended RPM range for these points is usually between 5,000 and 10,000 RPM.
• Always refer to the manufacturer’s recommendations for the specific rubber or polishing points you are using.

Flap Wheels:

• Flap wheels and discs may be used for material removal or finishing. The recommended RPM depends on the specific product and application.
• Typically, RPMs for flap wheels range from 2,000 to 5,000, but this can vary.
• Follow the manufacturer’s guidelines for the specific flap wheel or disc in use.

The importance of surface speed in finishing

If you are using different diameter consumables on one workpiece but, want to achieve a consistent finish throughout then surface speed is important. This is because it doesn’t matter whether you use e.g. a 30mm flap wheel or a 150mm flap wheel, as long as you have the same surface speed you will achieve a consistent finish. You just need to adjust the RPM to achieve this.

Surface speed is related to the linear velocity of a rotating object’s outer edge and is important for applications where the interaction between the object’s surface and a workpiece is critical.

Example of working out surface speed on Stainless steel using a flap wheel

This calculation is based on a 30mm diameter flap wheel (94.2mm)

• Work out the diameter x Pi (3.14) you’ll need this later.

SS (24) x 60 = 1440 (mtr/min)
1440 x 1000 = 1,440,000 (mm/min)
1,440,000 / 94.2 = 15,319 (15,000 rpm)

So now you know that to run a 30mm diameter wheel at 24 Mtr/sec surface speed you would need to be at 15,000rpm

For a 50mm wheel it’s the same calculation:

• Work out the diameter 50 x pi = 157mm

SS(24) x 60 = 1440 (mtr/min)
1440 x 1000 = 1,440,000 (mm/min)
1,440,000 / 157 = 9,171 (9,000 rpm)

More Information

For more information on surface finishing give us a call – we have experts here who have been polishing for years!

And take a look at our You Tube page for videos of us hard at work finishing!