Mar 12, 2020
“Parts, which have been produced from melt by non-cutting molding (e.g. by pressing, compression molding or injection molding) in all side closed molds” are referred
to as molded parts according to DIN 7708, sheet 1 [freely translated].
Thus in injection molding, the end product, which is produced by filling the cavity with molten plastic, is called a molded part.
It should be noted that a possibly existing cold runner is not a component of the molded part.
Nov 21, 2018
An injection mold consists in general of two halves: injection side and ejection side.
The touching faces between these two halves are called parting line.
Through this, the air is transported from the cavity to the outside.
When the mold is opened, part and cold runner are separated from the mold at this line and ejected.
The parting line emerges in general as a surrounding seam on the part.
Mar 14, 2023
If a cold runner is used to gate directly on a part, there is only one way to separate runner and part automatically.
This is by using a pin gate.
The mold needs to have 3 plates in this case and will get more complex.
During design phase of a pin gate it needs to be kept in mind to have the gate height between 0,5mm to 1mm and the gate diameter in between 40%to 80% of the part wall thickness.
This is to make sure the automatic separation will work properly during mold open.
Injection
mold: Filling of a
cavity using a
pin gate
Related topics:
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jan 28, 2019
In injection molds with conventional cooling, the cooling system is manufactured with as little as possible drill holes.
A change in direction is realized by intersecting drill holes.
These auxiliary holes need to be closed by a plug to avoid the coolant flowing out of the mold.
Additionally plugs need to be inserted to define a clear direction of the coolant stream.
This way the coolant can flow through a drill hole in multiple areas.
The plugs prevent the coolant to flow into uncertain directions and support with the enforced flow direction a good cooling system of the mold.
Sep 3, 2020
The pressure at different positions inside the cavity/runner is called “Pressure Distribution”.
Ideally in injection molding process, the pressure distribution should be uniform throughout the cavity after the molten plastic completely fills the cavity. In this case the molded part shrinks uniformly.
In reality due to the different cooling behaviour of the part there is always a difference in pressure distribution.
Injection molding simulation is a great tool to predict the pressure inside the cavity, which can help to achieve uniform pressure distribution as good as possible.
