Posts: 2
From:West Yorkshire United Kingdom
Registered: Jan 2006

posted January 20, 2006 04:25 PM               

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we have a Covema 150 single screw PPC extruder. We normally run at 215 degrees C, 1500Revs and 3000PSi pressur using standard PPC granulat and sometime black colourbatch at 1% (PP based)
since yesterday suddenly the extruder does not want to accept the normal quantity fed in via the maquire 2 component blender and the motor struggles to turn the screw at max 50 revs pulling then 600AMps at which it cuts out. we have cleared the screens, the die, the bloc, but not yet pulled the screw as this is a majot job.
Anybody around who has experience with this and what to do???? We purged the barrel and even increased the temps to 230 degrees Celsius to clear it. this took more than 6 hours.. When we feed the PPC in very slow and very gradual the extruder runs again at max revs and only 300AMps. We are desperate !!!!!!!

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Posts: 680
From:Brodheadsville, PA USA
Registered: Jun 2001

posted January 20, 2006 09:34 PM               

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Possibilities;

A broken screw peice which has wedged itself in the screw.

A bad single heater in a bank of heaters in a zone.

A hole in the barrel or throat which is acting as a feeding groove.

Good luck,

Tom C

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Posts: 2
From:West Yorkshire United Kingdom
Registered: Jan 2006

posted January 25, 2006 02:50 AM               

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we have resolved the problem. The 350HP DC motor that drives the gearbox of the extruder had a fault with the DC injector which resulted in the rapid increase of the AMPS pulled and the reduced screw performance.

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