Posts: 2
From:
Registered: Dec 2004

posted December 29, 2004 08:29 AM               

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Hi all.
We have a problem with one of our extrusion lines. We are a polystrene foam plate producer. Our SACM645 alloy steel,nitro carburated,polished and chrome plated 150mm barrier cooling screw bored to feed section depth has been stuck inside the line when worked for about 2 horus. we wer able to remove it with a hydraluic pump and noticed that some of the parts of the beginning of the screw has been peeled off.
We do not now what to do and our production has stopped. i would love to send the pictures but do not know how to do that
thanks in advance

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Posts: 337
From:New Zealand
Registered: Jun 2001

posted December 29, 2004 01:52 PM               

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Is the screw new? what happened with melt and barrel temps over the two hour run period before binding occured.

Steve

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Posts: 422
From:Brodheadsville, PA USA
Registered: Jun 2001

posted December 29, 2004 04:59 PM               

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Were you operating with screw cooling?

Tom C

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Posts: 2
From:
Registered: Dec 2004

posted December 30, 2004 01:38 AM               

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thanks for the replies.
we cleaned the machine and emptied all the product in the line before operating for 2 hours. We think this should be the reason of our problem. When the screw operated without any raw material the problem occured. anyway thats what we think. You proffesionals can lead us to other opinions.
What we want to learn is what can be done about this problem the other parts of the screw is looking fine but we are not sure to load it back to the machine. Would that be any problem if we load it or would it be working fine without those peeled off lines.

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Posts: 422
From:Brodheadsville, PA USA
Registered: Jun 2001

posted December 30, 2004 09:57 AM               

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Why would your company run a screw dry for 2 hours? No lubrication at all? What would one expect when rubbing metal parts together without lubrication for hours?

Tom C

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Posts: 337
From:New Zealand
Registered: Jun 2001

posted December 30, 2004 01:37 PM               

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quote:

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When the screw operated without any raw material the problem occured. anyway thats what we think.

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And you're quite right, the inflow of material feeding a plasticating extruder serves two useful functions, cooling the screw and lubricating it.
The bigger the screw (both Dia and lenght) the greater the tendency to deflect (sag), with no melt film between the top of each flight and the bottom of the barrel, galling will take place.

Steve

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