Sumitomo Demag Alarm 220: Clamp Force Not Reached - Diagnostics & Troubleshooting
Published: 2026-05-27
Sumitomo Demag Alarm 220 triggers when the NC5 (or NC5 plus) controller detects that the actual clamping force measured at the tie-bar strain sensors fails to reach the programmed set-point within the allowed time window. On Sumitomo Demag Systec...
Sumitomo Demag Alarm 220 triggers when the NC5 (or NC5 plus) controller detects that the actual clamping force measured at the tie-bar strain sensors fails to reach the programmed set-point within the allowed time window. On Sumitomo Demag Systec and El-Exis SP series machines, clamping force is measured directly via strain gauges on each of the four tie-bars—this direct measurement approach provides more accurate force feedback than hydraulic pressure-based systems, but also means any mechanical issue affecting tie-bar loading will trigger this alarm.
Common root causes: (1) Hydraulic pump not delivering design pressure—check pump output pressure with a calibrated gauge at the clamp manifold. On Systec machines with variable-displacement pumps, the swash plate angle may be stuck at partial stroke. (2) Internal leakage in the clamp cylinder—worn piston seals allow hydraulic fluid to bypass without building full pressure. Monitor clamp cylinder drift with the mold closed under pressure. (3) Air trapped in the clamp cylinder after hydraulic oil change or maintenance—bleed the clamp circuit using the air-bleed valves (consult machine-specific hydraulic schematic for bleed point locations). (4) Tie-bar nut loosening—if one tie-bar has backed off its adjustment nut, the clamping force distribution becomes uneven and the total measured force drops. Check tie-bar elongation values with an ultrasonic bolt meter.
Alarm Details
| Alarm Code | 220 |
|---|---|
| Brand / Machine | Sumitomo Demag |
| Severity | High (Cycle Interruption) |
| Component | Clamping Unit / Hydraulic System |
| Affected Systems | Clamp Cylinder / NC5 Controller |
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 |
|---|---|
| Netstal Alarm 301 | |
| Engel Clamp Force Alarm |
Frequently Asked Questions
How do Sumitomo Demag tie-bar strain sensors differ from hydraulic pressure-based clamp force measurement?
Sumitomo Demag NC5 controllers measure clamping force directly via strain gauges bonded to each of the four tie-bars. This provides true clamp force measurement independent of friction losses in the clamp mechanism or hydraulic pressure fluctuations. Hydraulic pressure-based systems (common on older machines) measure pressure in the clamp cylinder and calculate force as Pressure × Piston Area—but this ignores seal friction (~5-10% loss) and assumes the hydraulic pressure transducer is perfectly calibrated. The direct strain-gauge method is more accurate (±1% vs ±5% for hydraulic), but the strain gauges are sensitive to tie-bar bending from uneven mold mounting—always verify tie-bar elongation symmetry after mold changes.
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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