Timing belts play a critical role in the operation of precision machinery, ensuring the seamless coordination of various components within a drive system. However, despite their seemingly simple design, timing belts are susceptible to a range of issues that can lead to failure, causing disruptions and potentially costly damages. When timing belts are used within the limits of their specifications, they will provide long and efficient service life. However, there are external forces and issues that will cause belt failure. The vast majority of these failures are fixable, or even avoidable. Consulting with a timing belt expert with ensure that failure is not a option.
Below, we will explore the most common types of timing belt failures, exploring the root causes, potential consequences, and most importantly, the corrective actions to keep your machinery ticking with precision. From the subtleties of temperature-related issues to the complexities of misalignment and tension irregularities, our guide aims to demystify the common problems associated with timing belts.
Timing Belt Tooth Shear
Issue: Timing belt teeth are coming away from the belt base
Problem
Solution
Misaligned drive
check pulleys for proper alignment
Mismatched timing belt and pulley
Be sure you are using a pulley of the same pitch as your timing belt
Timing belt pretention may be too low
Determine the proper pretension for your belt pitch and width and adjust accordingly.
Pulley diameter is too small
Switch to a pulley with more teeth. Be sure your pulleys are properly sized for your drive.
Excessive load
Adjust your drive with a stronger, larger timing belt and components that can handle the load.
Back bending idler is slipping
Change to an inside idler.
Tensile Failure
Issue: The timing belt has snapped
Problem
Solution
Excessive load
Adjust load or change drive to accomodate load
Extreme belt overtensining
This would be avoidable with proper pretension. Replace belt
Misalignment
Adjust pulleys for proper alignment and change belt
Debris in drive
Keep drive free of particulate.
Excessive load
Adjust your drive with a stronger, larger timing belt and components that can handle the load.
Back bending idler is slipping
Change to an inside idler.
Timing Belt Running Hot
Issue: Timing belt is getting hot even though they are in an ambient environment
Problem
Solution
Misaligned drive
Check parallel and angular alignment of timing belt pulleys
Improper Pretension
Utilize the SM5 Tension meter and phone app to calculate and set proper pretension
Timing belt tooth profile and pulley are not a perfect match
Verify the pitch of both the timing belt and pulley. Using BRECOflex components together guarantees perfect meshing
Timing Issues in a High Precision Drive
Issue: Backlash is causing in error in precision
Problem
Solution
Settling time isn’t fast enough
Switch to a stiffer timing belt such as move-series
Timing belt has too much play in the pulley
Switch to a zero backlash pulley
Belt Edges are Wearing
Issue: The belt edges are wearing causing damage to the belt or exposing tension members
Problem
Solution
Improper Tracking
Check the alignment of the pulleys
Timing belt is hitting an obstruction or blemish on the pulley flange
Repair the flange or replace with a new flange
Timing belt is too wide for the pulley
Replace with properly fitting components.
Improper pretension
Adjust to proper pretension using the SM5 tension meter.
Timing belt is scraping along the drive guard
Consider replacing belt with a self-tracking version.
Timing Belt is not Tracking Properly
Issue: The timing belt is not tracking straight.
Problem
Solution
Belt edge wear
Check pulley alignment. See section on edge wear
Weak support structure
Reinforce with a slider bed
Pulley has not flange
Switch to pulleys with flanges or a self-tracking timing belt.
minimize the polygonal effect with continuous tooth engagement. Reduce the belt width or used a lower tooth. Use a coated belt such as move-series
Air Displacement by the teeth on the pulley
Use multiple smaller belts. Cut air grooves in the pulley
Friction between the belt and the pulley
Try PAZ to minimize friction on the tooth side. Try a dry lube or silicone grease. Check pulley and belt sizing for meshing issues. Switch to a BAT/BATK belt which reduces friction and vents air toward the belt edges, reducing noise
Resonance frequencies
change driving RPM. Use a belt like ARC Power to reduce polygonal effect.
Cracks in the Belt
Issue: cracks are forming in the polyurethane timing belt or belt backing
