PVC tubing bonding
PVC tubing bonding
(OP)
We have experienced some cracks in the PVC tubing asembly. After investigation, we have the hypothesis that this craks in the joints could come from a non correct extrusión process temperatures, since the tubing appears to have very high shrinkage rates (9-10%). Have anybody experienced the same issues? Thanks for your help.





RE: PVC tubing bonding
Rick Fischer
Principal Engineer
Argonne National Laboratory
RE: PVC tubing bonding
José Luis Zafrilla
Plant Technical Manager in Grifols
RE: PVC tubing bonding
Rick Fischer
Principal Engineer
Argonne National Laboratory
RE: PVC tubing bonding
Thanks Rick
RE: PVC tubing bonding
So you are saying its a new screw in an existing machine? Was this done to replace a worn screw, i.e. new screw has same specs as old screw, or is the new screw of a different design?
Is this rigid PVC or plasticized? My limited experience is with rigid. If this is rigid PVC, you could check your material properties by running a tensile test and comparing elongation to values from the resin supplier. If you have a piece of tube from the previous screw, run tensile on that and compare to the new stuff. If your testing produces a stable neck and draws out, your material is not too bad. If you cant get a good tensile specimen, run an Izod impact test. If you suspect process temperature issues, you should be looking to see if your material has undergone complete gelation. There are many papers dealing with this, one is below.
https://www.perkinelmer.com/lab-solutions/resource...
Rick Fischer
Principal Engineer
Argonne National Laboratory