May 6, 2021
For the production of injection molded parts a mold is necessary to be placed on the injection molding machine.
It is commonly build out of steel or aluminum and is designed as a permanent form.
Depending on the plastic material used millions of parts can be created with one mold.
The complexity of a mold range from a simple two-plate molds up to a complex stack mold with sliders, etc.
To avoid additional costs it is important to think about the mold concept early in the concept phase of part design.
Injection mold: 15 year old and more than 750000
parts produced.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Feb 15, 2019
In injection molding, during filling and packing phase the two mold halves are hold closed with the clamping force against the pressure of the melt. If the driving force of the cavity pressure is higher than the clamping force, the mold is pushed open by a few thousandths to hundreds of millimeters. This is known as the so-called mold breathing. Too large mold breathing can lead to flash formation, while too low mold breathing results to air compression with burn marks.
In order to optimize the required clamping force, dial gauges can be attached to the mold to determine the mold breathing. Permissible respiration depends on the quality requirements of the injection molded part, the material and the size of the machine.
May 29, 2019
The sequential process during the injection of the melt into the cavity until the part is cooled down, is called mold filling phase.
After the volumetric filling of the cavity (95% to 98% of the cavities volume), (A) there is a switch-over from injection to packing.
During this phase the material is packed and pressed to the mold wall (B).
After the switch over point the complete filling (100%) of the cavity takes place.
During the packing phase (C) the material will be compressed is in good contact with the mold wall.
The plastic shrinks while it is cooling down (approximately 0,2 – 2,0 %).
Shrinkage is compensated in the packing phase due to a material delivery through the melting core. This is important to ensure the dimensions of the part itself.
After the packing phase, cooling phase will start (D). Here the part will be cooled down to a point, where the dimensional stability can be ensured (to ejection temperature) and ejection can be done without deformations on the part.
Apr 6, 2021
Plates, which contain the part-cavity in the injection mold are called mold plates.
Usually there is one mold plate for the injection side and one for the ejection side.
Dependent on the complexity of the part, the cavity is carved directly into the mold plate or embeded with inserts into the mold plate.
The primary cooling system of the cavity is located in the mold plates as well.
May 25, 2021
In injection molding, the process of finding the best possible setting on the injection molding machine is called mold sampling.
The aim is to find the parameters that ensure the best possible quality for the molded part and compliance with given dimensions and tolerances
It is important that the setting of the parameters is always reproducible, i.e. controllable. In this context, the documentation of the parameters found therefore has top priority.
Systematic tool sampling ensures an economical process, high-quality parts and a trouble-free series process.
Quality assurance: Documentation of the process parameters via the IMG programme
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
