4192

Common Causes

• Mechanical overload from machining: too-heavy cut, dull tool, crash damage or excessive feed
• Mechanical binding on the axis (ballscrew, guideway, bearing) raising motor load
• Motor internal fault (winding, bearing) causing high current draw
• Incorrect or corrupted servo data file setting the wrong protection curve

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code YYYY = Gamma of the protection curve that detected the overload; code ZZZZ = Internally calculated overload data value
2. 2Note the object (axis name, or none = spindle) and record the YYYYZZZZ code: YYYY is the protection curve gamma used, ZZZZ is the calculated overload data — give both to service if needed.
3. 3Check the cutting conditions at the time of the alarm: reduce depth of cut/feed, replace a worn or dull tool, and retry at lighter load.
4. 4With power locked out, move the axis by hand (or rotate the spindle) to feel for binding; inspect ballscrew, guideway lubrication and bearings for damage or chip contamination.
5. 5Check the motor for abnormal heating, noise or smell; measure winding insulation/resistance if a motor fault is suspected (lockout and discharge first).
6. 6If mechanical and cutting causes are eliminated, have the servo data file verified against the correct file for this machine, as a wrong file can set an inappropriate overload curve.
7. 7If the alarm returns after these checks, record the alarm number, code and object and contact Okuma service.