VFA are periodic surface artifacts commonly associated with stepper behavior, belts, pulleys and specific speed ranges. They differ from ringing, which appears as decaying waves after a sharp feature.
How do you recognize it?
- Regular vertical bands
- Pattern changes with speed
- Most visible on smooth walls
Common causes
- Unfavorable speed range
- Motor/belt excitation
- Pulley or belt geometry
- Mechanical resonance
What should you check first?
- Run a controlled VFA speed test.
- Compare speed ranges instead of only slowing everything down.
- Inspect belts and pulleys for mechanical issues.