Hi, i am trying to injection molding out a tube with thickness wall of 3mm, the total length is 110mm. The product has bad sink mark, bubbles and other visual defect. Is that any way of improving them.
Start with the basics: Check your venting, gate and runner diameter. Check that the nozzle dia of the machine is big enough. Check that your mold temperature is not too cold. Check you barrel zone temperatures are to the book.
Checking your gate diameter. If it is too small it will freeze off before you begin to pack the material. If it is too large you may get a sucking back effect and sink around the gate as you cannot freeze off while packing. Make sure your check ring is working correctly.
Is the barrel sized correctly for the volume. Is it a single cavity mold. How/where is it gated?
Have you followed the drying instructions. Bubbles are sometimes caused by bad gate location where you are filling a thin section prior to a thicker wall. Gate into the thickest section and allow the plastic to impinge on a wall opposite the gate at a distance equal to the wall section.
Consider a second gate carefully before opting for it. I have seen 96 cavity parison molds for the 2 litre coke bottles and they mold the completed neck of the bottle and what seemed like a very thick wall sectioned tube ~ 100mm long through a single gate at the bottom of the closed end of the tube.
In your case you may have to mold with a closed end and then second op it.
Thick PET Tubes
Re: Thick PET Tubes
