Dec 19, 2018
The inherent cause for the shrinkage, in injection molded parts, is the thermodynamic behavior of the material.
This behavior is shown in the pvT-diagram, in which the specific volume (v) is presented as a function of pressure (p) and temperature (T).
It characterizes the compressibility and thermal expansion of polymers.
There is an essential different pvT behavior between amorphous and semi-crystalline materials.
In the picture there are three different pressure curve shown p0, p1, p2 for each material type.
As a melt, both show a linear dependency of the specific volume on the temperature.
For the solid phase, amorphous materials (green) also have a linear dependency.
While semi-crystalline materials (red), on the other side, show an exponential decrease of the specific volume at decreasing temperatures.
These different behaviors, in the pvT-Diagram, explain the reason for the higher shrinkage of semi-crystalline thermoplastics compared to amorphes materials.
Feb 26, 2026
A structured transfer of simulation-relevant data throughout the entire injection molding process chain is enabled by a specially developed file format with the extension .pxs. This format functions as a dynamic data container that consolidates results from rheological calculations, structural analyses, and material and machine data. Thanks to its flexible structure, it can be loaded by various software tools and machines, each extracting only the information required for the respective process step. As a result, the format ensures consistent and automated data flow from part and mold design to production and quality assurance. At the same time, it provides a foundation for increasingly autonomous manufacturing workflows in injection molding.
Illustration
Related topics:
Digital process chain
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jan 17, 2019
The definition of quality according to DIN 55 350/T11 is “the nature of a unit as its suitability to meet specified and required needs”.
Different factors are used to evaluate the quality of plastic parts.
The easiest is the optical evaluation.
Visible surfaces should not contain streaks, burn marks, sink marks and/ or air traps.
The dimensional examination is used to control the functionality of the part.
Shrinkage and Warpage are main quality criteria.
The technical drawing shows the necessary tolerances of the part for an acceptable quality.
Mechanical testings are necessary to check the different applied forces on the part dependent on its usage.
Fiber orientation, weld lines, voids and wall thickness may lead to this quality failure.
The choice of the material and the processing, both influence the mentioned quality factors decisively.
Injection molding simulation and additional structure analysis help to check the quality of a part in advance.
Oct 25, 2019
One measuring device for round outside diameters of for example shafts, bolts or pipes is called outside micrometer or quick micrometer.
The micrometer and the bracket form a fixed unit. The measuring ranges in trade and industry are mostly between 0 and 500 mm.
There are micrometers that have plates with a larger diameter than the screw shaft to measure gear
toothing. These are called plate or flank micrometers.
Radial grooves are measured with outside micrometers with flat and leveled measuring surfaces. Furthermore there are inserts with tapered measuring surfaces.
External threads of screws, threaded bolts, etc. are measured with outer micrometers, which have changing inserts to adapt to the pitch and type of thread.
Measuring Technology: Outside
micrometer for the measurement of outer diameters between 25 and 50 mm.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Oct 25, 2019
X-Rays can penetrate matter. It is weakened differently depending on the type of material. The attenuation of X-rays is the most important factor in radiographic imaging.
The radiation intensity of the X-ray beam decreases exponentially with I = I_0e^-µx of the path length x traveled in the specific material.
Measuring technology: Dependent on thickness and material properties the
radiation intensity of the X-rays changes.
Related topics:
X-Rays
Detector
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
