Fanuc Roboshot SV0600 Injection Unit Servo Overload — Causes & Solutions
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-06-08
Fanuc Roboshot SV0600 is a servo amplifier overload alarm for the injection axis. The Fanuc servo amplifier monitors the motor current and temperature, and if the load exceeds the rated continuous torque for a programmed duration, the amplifier...
Fanuc Roboshot SV0600 is a servo amplifier overload alarm for the injection axis. The Fanuc servo amplifier monitors the motor current and temperature, and if the load exceeds the rated continuous torque for a programmed duration, the amplifier trips to protect the motor windings from thermal damage. This is fundamentally different from an overpressure alarm — the issue is not the injection pressure itself, but the sustained mechanical load on the servo drive system. The root cause is usually mechanical binding or increased friction in the injection unit's linear motion system.
Diagnostic sequence for all-electric machines: (1) Check the injection unit's linear guide rails and ball screw for contamination, lack of lubrication, or mechanical damage. All-electric machines like the Roboshot have no hydraulic system to mask mechanical binding — the servo motor directly feels every Newton of resistance. (2) Check the ball screw nut preload — over time, ball screw preload can increase due to contamination or decrease due to wear. Either condition causes increased servo load. (3) Verify the barrel temperature profile — if the material is not fully molten, the screw requires more torque to inject. This is a material preparation issue, not a servo issue. (4) Check the amplifier cooling fan and heat sink — a servo amplifier derates its continuous current rating when operating above its rated ambient temperature. A failed cooling fan can cause SV0600 on a machine that has run the same process for years without issues.
Alarm Details
| Alarm Code | SV0600 |
|---|---|
| Brand / Machine | Fanuc Roboshot |
| Severity | High (Machine Stop) |
| Component | Injection Servo Motor / Amplifier / Ball Screw / Linear Guides |
| Affected Systems | Injection Unit — Servo Drive System |
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 |
|---|---|
| Sumitomo Demag E340 Servo Overload | |
| Engel E350 Servo Overload |
Frequently Asked Questions
SV0600 trips intermittently — sometimes during startup, sometimes mid-production. Why intermittent?
Intermittent servo overload on an all-electric machine almost always points to a thermal issue. During startup, the barrel and material are cold — higher viscosity = higher injection torque. If the process pushes the servo near its limit at operating temperature, the cold-start condition will exceed it. If the alarm occurs mid-production, suspect the amplifier cooling system — as the amplifier heats up over hours of operation, it derates its output capacity. Clean the amplifier heat sink and verify the cooling fan is operating.
Can I increase the overload threshold to stop SV0600?
Never. The overload threshold exists to protect the servo motor windings from thermal damage. Increasing it will prevent the alarm but may allow the motor to overheat — a servo motor replacement costs $5,000-15,000. The correct response is to diagnose why the servo load is higher than expected and fix the mechanical or process root cause.
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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