Reviewing the previous pressure profile, Gerritsma believed that there was a cold slug
present in the old general-purpose tip, which required higher pressure to clear from the nozzle.
It also offers options with which users can specify runners, sprues, and Cold slug
This process results in a lower cavity and gate area temperature, lower injection pressures at injection start and no pushing into the product a cold slug
as is normally the case with single heater hot runner systems.
This curve shows what a cold slug
in the nozzle looks like.
Or, in one example, "a PVC pipe was found to have a crack that was caused by a cold slug
from the molding process." Such cracks can ultimately lead to part failure, and potentially, litigation.
We all know it is a good idea to have a runner overflow well at every runner turn, to capture any potential cold slug
. The same logic applies to the end of the runner.
According to the company, the exact location of the tip in the cavity insert--reaching all the way to the part surface--ensures that there will be no cold slug
; instead, a clean gate break is produced.
Not molding a disk could suck out too much heat and can cause a cold slug
to form behind the gate.
A dimple can be used to aid flow at the gate because it permits a well for the frozen cold slug
to be blown into.
If it is fully solidified, it is called a cold slug
. Cold slugs
typically cause a spike in the initial injection pressure as the screw tries to push this solid mass out of the nozzle tip.
This causes excessive heat loss that will result in a cold slug
, drooling, or stringing, all of which cost molders thousands each day.
This cold slug
remains in the gate during the mold-open step, part ejection, and mold-close motion.