KraussMaffei MC120: Back Pressure Control Deviation
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-06-02
KraussMaffei MC120: actual back pressure deviates >15% from setpoint. Critical for melt homogeneity. Causes: proportional valve sticking, transducer drift, air in hydraulic system.
KraussMaffei MC120: actual back pressure deviates >15% from setpoint. Critical for melt homogeneity. Causes: proportional valve sticking, transducer drift, air in hydraulic system.
Alarm Details
| Alarm Code | MC120 |
|---|---|
| Brand / Machine | KraussMaffei |
| Severity | Medium (Cycle Alarm) |
| Component | Back Pressure Valve / Transducer |
| Affected Systems | Plasticating Back Pressure Control |
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 |
|---|---|---|
| KraussMaffei OEM Heating Band | KM-HB-{zone} | $500-950 |
| KraussMaffei Thermocouple | KM-TC-{zone} | $140-300 |
| KraussMaffei MC6 Temperature Board | KM-MC6-TC | $1,800-3,500 |
| KraussMaffei Relay Card | KM-MC6-RELAY | $450-900 |
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 405 |
Frequently Asked Questions
Recommended back pressure for engineering resins?
Unfilled (PC, PMMA, PSU): 5-10 bar. Glass-filled (PA66 GF30): 3-5 bar to minimize fiber breakage. POM: 2-5 bar max (excess back pressure degrades POM).
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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