Technical Support

PROCESSING GUILINE

1. START UP
-  Clean screw and barrel before starting.  
-  In case to clean without taking off screw it is recommended to purge by LDPE (at temperature 120-160 deg C) with barrel head open. Run LDPE until no more old material remains in extruder. If we are not ready to start up we can keep LDPE in extruder and shutdown the machine and heat up again when we are ready.  
-  Set temperature profile as temperature guideline (LDPE is still in extruder).
-  Set up die head, insert conductor and center conductor wire.
-  Well mix Material A with Material B and feed to extruder. Then start to run cable.
2. RUNNING
-  For short time stop such as for die changing, some pre-crosslink may occur causes rough surface or scorched material. In this case the problem will finish after old material is purged out by new material. After new material comes out, continue the process.
-  For long time stop, it is recommended to purge extruder with LDPE to finish all
remained XLPE before runing the extruder.
3. SHUTDOWN
-  Use LDPE to purge extruder until finish all remained XLPE. Then shutdown, the machine LDPE can be kept in extruder without any problem.
-  In other case to clean with taking off screw. It recommends cleaning cylinder by using PVC then taking off screw and removing all remaining PVC.
4. EQUIPMENT
-  Inside the machine from extruder, screw, barrel to die head should be streamline to avoid any dead spot or places where material can stick on.  When XLPE stick in extruder or die head without moving it can begin to cure and cause scorched material come out on the cable.
-  Apply gas flame at die tip can improve surface finish.

 

SIOPLAS SYSTEM PROCESSING TROUBLESHOOTING FOR WIRE AND CABLE


       The following trouble shooting tips are provide to the processor in the even that a problem
        should occur during extrusion of wire coating using silane crosslinkable polyethylene. 

 

Problem Possible cause Suggested remedy

 

Poor surface finish

Moisture in catalyst/color masterbatch .  Dry masterbatch per recommendations
Drooling Place flame at die tip
Temperator too low Raise temperature profile
Poor die design Increase die land /increase drawdown

 

Gel information

Moisture in catalyst masterbatch Dry catalyst per recommendations 
High melt temperature Verify / reduce temperature profile
Old product Verify production date have product check if more than 12 months old discard any remixed compound
Exessive residence time Increase screw  RPM/ check for brigding in feed section

 

Low output

 Scorch material    Inspect and clean tooling and extruder
 Bridging  Decrease temperature in feed section
 Low melt temperature  Increase temperator profile
 High back pressure  Change screen and adjust gum space

 

High melt temerator

 Temperature profile too high  Reduce temperator profile
 Die design  Increase die land
 Screen logged  Change screens/ determine source of clogging
 Screen pack too fine  Use coarser screens
 Voids Too rapid cooling Use hot water in cooling trough as per recommendations 
 Poor Adhesion / Shrink back on conductor Conductor  too cold Prehead conductor
 Too rapid cooling  Use hot water in cooling trough as per recommendations