Milacron Alarm M-450: Injection Unit Overload — Root Cause & Repair Guide
Published: 2026-05-28
Milacron M-450 is an injection unit overload alarm indicating the injection motor (electric machines) or hydraulic pump (hydraulic machines) has exceeded its rated load for a sustained period exceeding the drive's thermal protection...
Milacron M-450 is an injection unit overload alarm indicating the injection motor (electric machines) or hydraulic pump (hydraulic machines) has exceeded its rated load for a sustained period exceeding the drive's thermal protection curve.
Systematic Root Cause Analysis
1. Check melt temperature: Cold material is the #1 cause of injection overload. Increase barrel temperature in 5°C increments and allow 15 minutes for stabilization between changes. 2. Inspect check ring: A worn check ring allows material to flow backward during injection, causing the controller to increase injection pressure/speed to compensate — overloading the drive. Replace if wear gap exceeds 0.15mm. 3. Verify injection speed profile: Excessive fill speed creates high dynamic pressure. Reduce injection velocity by 10% and observe. 4. Check nozzle orifice: A partially blocked nozzle or undersized orifice for the material grade causes excessive back-pressure. Clean or replace. 5. Inspect screw and barrel for wear: Excessive clearance between screw flights and barrel wall reduces pumping efficiency, forcing the drive to work harder. Measure screw diameter at multiple axial positions; replace if wear exceeds 2% of original diameter.
Alarm Details
| Alarm Code | M-450 |
|---|---|
| Brand / Machine | Milacron |
| Severity | High (Cycle Interrupt — Injection Unit Stop) |
| Component | Injection Motor / Hydraulic Pump Overload |
| Affected Systems | Injection Axis — Power Transmission |
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 |
|---|---|
| fanuc-roboshot-servo-alarm-sv0440 | |
| netstal-alarm-301 |
Related Diagnostics & Materials
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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