Fanuc Roboshot SV0440: Servo Overload Alarm — Troubleshooting & Preventive Maintenance
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-05-27
Fanuc Roboshot SV0440 is a servo overload alarm indicating that the servo amplifier has detected a sustained current draw exceeding its rated capacity. On all-electric Roboshot machines, this alarm most commonly affects the injection servo axis...
Fanuc Roboshot SV0440 is a servo overload alarm indicating that the servo amplifier has detected a sustained current draw exceeding its rated capacity. On all-electric Roboshot machines, this alarm most commonly affects the injection servo axis during high-pressure, long-duration holding phases.
Immediate Diagnostic Steps
1. Check Load Meter: On the Fanuc iHMI, check the servo load monitor for the affected axis. Sustained load above 80% during holding phase indicates excessive back-pressure from the material or process. 2. Reduce Holding Pressure: Temporarily reduce holding pressure by 10-15% to determine if the alarm clears. If it clears immediately, the root cause is process-related (excessive hold pressure or time). 3. Verify Barrel Temperature: Cold barrel zones force the servo to work harder. A failed heater band on the metering zone will cascade into excessive injection servo load. 4. Check Servo Motor Cooling Fan: The Fanuc servo motor uses an integral cooling fan. Fan failure causes motor temperature to rise and the amplifier to derate. Inspect and clean the fan filter.
Preventive Maintenance
Clean servo amplifier heat sinks every 6 months. Check motor insulation resistance annually. Monitor servo load trends over time — gradual increase indicates screw/barrel wear. Replace the check ring if servo load during holding phase shows a 15%+ increase vs baseline.
Alarm Details
| Alarm Code | SV0440 |
|---|---|
| Brand / Machine | Fanuc Roboshot |
| Severity | High (Axis Stop — Overheat Risk) |
| Component | Servo Amplifier / Motor |
| Affected Systems | Injection Servo Axis or Clamp Servo Axis |
Troubleshooting Protocol
Verify all electrical connections to the affected component. Check for loose wires, burnt connectors, or signs of arcing. Measure voltage at the component terminals.
Look for physical damage, corrosion, or wear. For heating bands: check for hot spots (discoloration). For sensors: check for damaged cables or contamination on the sensing surface.
For thermocouples: measure resistance (should be 2-10 ohms, not open circuit). For heating bands: measure resistance against the nameplate rating. For relays: test coil resistance and verify switching with a test signal.
Order the OEM replacement part (see OEM Parts table above). After replacement, run a full heat-up cycle and verify the alarm does not re-trigger. Document the replacement in the machine log.
OEM Replacement Parts
| Part Name | OEM Part Number | Est. Price |
|---|---|---|
| Fanuc OEM Heater Band | FAN-HB-{zone} | $350-650 |
| Fanuc Thermocouple | FAN-TC-{zone} | $90-180 |
| Fanuc Servo Amplifier Module | FAN-31i-AMP | $2,000-4,000 |
| Fanuc I/O Module | FAN-31i-IO | $600-1,200 |
Prices are estimated US market ranges. Contact your OEM distributor for exact pricing. {zone} = zone-specific variant.
Same Alarm on Other Machine Brands
If you operate multiple injection molding machine brands, the same fault may appear under different alarm codes:
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| engel-alarm-510 | |
| arburg-error-290 |
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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