The Importance of Concentricity in Rotary Drums and Tires (Riding Rings)

This article was authored by:

Carrie Carlson
Technical Writer

Quality fabrication is one of the most influential factors in maximizing the life of a rotary drum, whether it is a rotary dryer, cooler, kiln, or granulator. One critical aspect of drum fabrication is the concentricity of the drum and its supporting tires (riding rings).

Rotary drums and riding rings must be able to withstand the strenuous static and dynamic loads placed on them throughout their service life and concentricity contributes significantly to their ability to do so.

Concentric Rotary Dryer

FEECO Rotary Dryer

About Rotary Drum Concentricity

In layman’s terms, concentricity refers to the symmetrical balance of a circle or cylinder. Rotary drums and tires should be manufactured as close to perfect concentricity as possible, as this will promote optimal performance and longevity.

Rotary drums and tires can fall out of concentricity over time, particularly if the proper materials of construction were not chosen, or the drum shell thickness is not heavy-duty enough for the application at hand.

Factors That Influence Concentricity:

  • Manufacturing techniques, most notably steel rolling
  • Materials of construction
  • Shell thickness
  • Operating conditions

When a drum shell is not concentric, it is considered to be experiencing ovality, or in other words, it has fallen out of round. Some ovality is expected due to the flexing of the drum during rotation, but should be kept to a minimum.

Signs that a drum is not concentric, or experiencing ovality:

  • Cracks in the drum shell
  • Cracks in the tire
  • Vibrational noise during operation
  • Wobbling of the drum or tire during rotation

All rotary drums in theory start out concentric, but the amount of deviation away from concentricity is based on the rotary drum manufacturer’s fabrication techniques and quality control practices, with some manufacturers allowing higher tolerances than others.

In selecting a rotary drum manufacturer, ensure the manufacturer follows strict quality standards and can design the unit to withstand its intended level of duty. Doing so will promote smooth rotation and a long drum life, while also reducing maintenance and operational noise.

Benefits of a Concentric Drum Shell & Tires

  • Longer Equipment Life
  • Smooth Rotation and Minimal Operational Noise
  • Longer Tire Life
  • Reduced Maintenance

Rotary Drum Concentricity Infographic

FEECO manufactures the world’s most reputable rotary drums. All FEECO drums are manufactured according to stringent quality control standards, concentricity included, for long-term reliability. For more information about our rotary drums, contact us today!

About the Author . . .

Carrie Carlson is a technical writer and visual designer.

More About Carrie