Fanuc Roboshot Alarm SV0440: Servo Heatsink Overheating — Troubleshooting Guide
Published: 2026-06-04
Fanuc Roboshot Alarm SV0440 triggers when the servo drive unit's heatsink temperature sensor detects a condition exceeding the safe operating threshold (typically 80°C). The alarm is a protective shutdown designed to prevent permanent damage to...
Fanuc Roboshot Alarm SV0440 triggers when the servo drive unit's heatsink temperature sensor detects a condition exceeding the safe operating threshold (typically 80°C). The alarm is a protective shutdown designed to prevent permanent damage to the servo drive's IGBT power transistors, which degrade rapidly above their rated junction temperature. This alarm is especially common on Roboshot S-2000i series machines running high-speed thin-wall molding cycles with short cooling times.
Root cause: (1) Heatsink fan failure — the most common cause. Fan bearings wear out from continuous operation in the molding environment (dust, plastic fines, oil mist). (2) Cabinet ventilation blockage — air intake filters clogged with plastic fines, reducing airflow across the heatsink. (3) High ambient temperature in the molding cell — above 35°C ambient, the heatsink's passive cooling capacity is exceeded. (4) Servo drive running at peak current for extended periods — typically from excessive injection pressure or back pressure settings.
Alarm Details
| Alarm Code | SV0440 |
|---|---|
| Brand / Machine | Fanuc Roboshot |
| Severity | High (Machine Stop) |
| Component | Servo Drive / Heatsink Fan |
| Affected Systems | Injection Unit Servo Motor |
Troubleshooting Protocol
Identify which zone/component triggered the alarm. Record the error code, timestamp, and any measured deviation values shown on the diagnostic screen.
Power down the machine and follow Lock-Out Tag-Out procedures. Visually inspect the affected component for physical damage, loose connections, polymer leakage, or carbonized material.
Using a multimeter, check resistance/continuity on the affected circuit. Verify SSR functionality and fuse integrity. Compare readings to OEM specifications.
Replace the failed component with an OEM-approved part. Do not substitute with generic equivalents unless validated for the specific machine model and operating conditions.
Restart the machine, verify the alarm is cleared, run a test cycle, and document the root cause, repair performed, and parts replaced in the machine maintenance log.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Sumitomo Demag Servo Alarm | |
| Arburg Servo Drive Overheat |
Frequently Asked Questions
How can I monitor servo drive temperature trend to predict fan failure?
On Fanuc Roboshot controllers, navigate to Maintenance > Servo Monitor > Drive Temperature. Record the baseline temperature at the start of each shift. An upward trend of 5°C+ over baseline at the same cycle conditions indicates the heatsink fan is losing efficiency — replace it before SV0440 triggers. Fan replacement takes 15 minutes and costs ~$80; a failed servo drive replacement costs $3,000+ and requires a service call.
Related Diagnostics & Materials
Netstal Alarm 102: Heating Zone Temperature Out of Range...
Netstal Alarm 102 occurs when the actual temperature of a specific heating band in the injection barrel deviates...
Arburg Error 320: Barrel Heating Control Failure -...
Arburg Error 320 is a critical interlock alarm triggered when the Selogica controller detects no current flow to one...
Engel Alarm 405: Screw Recovery Time Exceeded - Diagnostics & Fix
Engel Alarm 405 is generated by the CC300 controller when the screw recovery (plastication) time exceeds the maximum...
Netstal Alarm 301: Mold Protection Force Exceeded -...
Netstal Alarm 301 is one of the most critical safety alarms in injection molding—it triggers when the clamping unit...
Sumitomo Demag Alarm 220: Clamp Force Not Reached -...
Sumitomo Demag Alarm 220 triggers when the NC5 (or NC5 plus) controller detects that the actual clamping force...
KraussMaffei Alarm MC45: Injection Pressure Limit...
KraussMaffei Alarm MC45 is generated by the MC6 controller (KM's latest-generation control platform) when the...
Wittmann Battenfeld Alarm B6: Ejector Position Fault -...
Wittmann Battenfeld Alarm B6 triggers on the Unilog B8 (or B6/B6P) controller when the ejector system fails to reach...
Arburg Error 290: Screw Rotation Speed Deviation -...
Arburg Error 290 is triggered by the Selogica controller when the actual screw rotation speed (measured by the screw...
References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org