Dec 3, 2018
The temperature of the injection molding machine is controlled during the complete cycle.
As the cooling system is always active, the length of the cooling time is not clearly defined.
During the filling, the melt moists the cavity only partly.
This is the reason for the definition of the cooling time from the end of injection until ejection.
That means, the cooling time equals the packing time (green line) plus the residual cooling time (blue line in the time-pressure-diagram).
Jan 9, 2019
Even when the mold halves are exactly centered on top of each other, core shift might happen.
Especially long, thin cores are pushed away due to unbalanced filling.
The unbalanced injection of the melt leads to a one-sided pressure on the core.
The movement results in changing wall thickness in the part.
In the area of reduced wall thickness, the filling is more difficult than in the are with higher wall thickness.
Weaknesses, given by to the changed wall thickness, lead to problems during the usage of the part.
A balanced flow around the core and a hold on both sides of it helps to reduce the risk of core shift.
Dec 3, 2018
The injection molding process contains different stages:
After the injection time (1), the packing time (2) and residual cooling time (3) follow.
The cycle will be completed with the mold movement (open, eject and closing) (4).
When all stages passed one time it is called a cycle and the process starts again.
Mar 2, 2020
The maintenance of an injection mold is often determined by the number of shots. Where a shot represent one cycle in the injection molding process.
In order to determine the number of cycles a cycle counters can be mounted onto the mold.
A pin is usually pressed into the counter while the mold is closing. Thus the counter is moved one step further.
But it need to be kept in mind that this means the counter does not check whether parts are actually produced or nut, but show how often the mold was closed.
The cycle counter that can be set on the machine controller can be reset to zero any time. This, and the fact that the mold can be used for production on different machines, makes the cycle counter on the machine controller not usable to determine the total number of shots done.
Feb 20, 2024
When manufacturing silicone parts by injection molding, removing air from the mold before injecting the material is a crucial step to ensure optimal product quality.
This process, known as mold evacuation, is used to avoid air bubbles and inclusions in the final product,
which could otherwise negatively affect the mechanical properties and aesthetic appearance.
By removing air from the mold cavity, the viscous silicone material can be evenly distributed and fill all areas of the mold.
This leads to increased accuracy of the component geometry and improved surface quality.
The use of this process is particularly important in silicone processing, as it ensures product consistency and significantly reduces the likelihood of production errors.
You can also find out more about injection molding of liquid silicones here:
https://www.plexpert.ca/de/plexpert-elearning/10709_spritzgiessen-von-fluessigsilikon-lsr/
Injection Molding Process: A vacuum pump sucks air out of the tool
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
