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inner shielding protruding in insulation

6 years 1 month ago - 6 years 1 month ago #2684 by Mr raj sharma

We are facing a problem in CCV line of Inner shielding material is inserting in the insulation layer in running line. This problem is mainly coming in 11 kV cable core. Can any anyone suggest the reason behind this.

Any suggestion is welcomed.

Last edit: 6 years 1 month ago by Peter J Stewart-Hay.

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6 years 1 month ago - 6 years 1 month ago #2687 by Peter J Stewart-Hay
Hello Mr. Sharma;

Here are the things I would be looking at if it was my machine:

1 Confirm that you are using a proper triple crosshead and not an old fashioned 1+1+1 or a 1+2 crosshead configuration.
2 Confirm that your crosshead was manufactured by a reputable extrusion machinery manufacturer with a history of manufacturing excellent triple crossheads.
3 Confirm that your inner shield screw and barrel are in good shape and free of scratches, dents or any other mechanical damage.
4 Recall that the screen pack is to hold back pressure in the extruder and not a filter device.
5 Confirm that you are not finding pre-cured XLPE in your extruder after a run and that you are cleaning out the extruder, screw and crosshead on a regular basis.
6 As with the extruder, make sure the tooling is of correct design and that the surfaces touching the inner surface of the insulation and the outer surface of the inner shield are not damaged or scratched.
7 The transfer tube for the inner shield can have a long length to diameter ratio. This can result in premature cross linking by shear in the tube. Check it out!
8 Confirm that all control thermocouples are seated properly and are operating properly.
9 Confirm that the temperature controllers are operating correctly and calibrated recently.
10 Confirm that the screw cooling system is working correctly.
11 Confirm that the melt temperature of the inner shield material is correct.
12 Confirm that your inner shield material is good has been properly dried to a -40C Dew Point

Somewhere in there is your issue but we cannot do anything else from afar.

Peter J. Stewart-Hay Principal
Stewart-Hay Associates
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Last edit: 6 years 1 month ago by Peter J Stewart-Hay.

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