Netstal Alarm 301: Injection Pressure Exceeded — Troubleshooting Guide
Published: 2026-05-27
Alarm 301 on Netstal injection molding machines indicates that the actual injection pressure has exceeded the set maximum pressure limit during the injection phase. This is a cycle-interrupt alarm — the machine stops the current shot to prevent...
Alarm 301 on Netstal injection molding machines indicates that the actual injection pressure has exceeded the set maximum pressure limit during the injection phase. This is a cycle-interrupt alarm — the machine stops the current shot to prevent mold or machine damage.
Root Cause Diagnosis
1. Blocked Nozzle Tip (60% of cases): Degraded polymer, unmelted granules, or contamination blocking the nozzle orifice creates back-pressure that triggers the alarm. Purge the barrel and inspect the nozzle tip for carbonized material. 2. Frozen Gate (20%): In cold-runner molds, a gate that has frozen prematurely requires excessive injection pressure to push through. Verify mold temperature, reduce cooling time, or increase gate size. 3. Melt Temperature Too Low (10%): Cold melt has higher viscosity. Increase barrel temperature in 5-10°C increments. 4. Faulty Pressure Transducer (5%): A failing transducer provides false-high readings. Test with a calibrated external gauge.
Immediate Actions
1. Check actual vs setpoint on the diagnostic screen. 2. Purge barrel at maximum temperature for the material. 3. Inspect nozzle and check ring for wear. 4. Verify transducer zero calibration. 5. Reduce injection speed by 10-15% as a temporary measure while diagnosing root cause.
Alarm Details
| Alarm Code | 301 |
|---|---|
| Brand / Machine | Netstal |
| Severity | High (Cycle Interrupt) |
| Component | Injection Unit / Pressure Transducer |
| Affected Systems | Injection Axis — Hydraulic Pressure Control |
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 |
|---|---|
| engel-alarm-405 | |
| arburg-error-320 |
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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