May 31, 2019
Most of the resin used in injection molding are hygroscopic (water attracting).
After drying the plastic resin, a defined residual moisture content shall be ensured within the material.
This needs to be checked according to the specifications of the material supplier.
If the residual moisture is too high, there is an increased risk of air traps, void and other defects.
In addition to that, the mechanical properties of the part will be reduced, too.
Considering this, it is vital to measure the residual moisture content of plastic material before drying and before using it in injection molding.
Quality: Portable residual moisture meter.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Sep 10, 2020
Many injection molded parts are produced in a short time, therefore it is usually not possible to examine all parts precisely.
For this reason, only a certain number of parts are taken out of production and used for the exact evaluation.
These parts form the so-called sampling size.
There is no general rule how large a sampling size should be.
However, the more parts are inspected, the more likely the results will apply to the remaining and not tested parts.
It is therefore necessary to weigh up the time, financial and human resources against the frequency of a defect in order to determine the appropriate sampling size.
Quality Assurance: Selection of the
sampling size from a certain quantity of
parts
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Target Weight
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Sep 17, 2024
This term refers to an index named after Albert Ferdinand Shore, which is a measure of the elasticity and hardness of materials such as rubber and plastics.
It is measured using a durometer, which presses a spring-loaded pin into the surface of the material. The Shore hardness is specified in different scales, with Shore A being used for softer materials and Shore D for harder materials.
The measured value ranges from 0 (very soft) to 100 (very hard). The higher the value, the harder the material. The Shore hardness is important for the selection of materials in applications where certain elasticity and hardness properties are required.
Further information can be found in the following standards: DIN ISO 7619-1, DIN EN ISO 868, DIN 53505 and ASTM D 2240.
Quality: Differences between the Shore A and Shore D measurement methods
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
May 10, 2019
Due to the predominate laminar flow regime in injection molding processes, primarily static mixers have the task to homogenize the melt temperature and equalizing the flow profile.
The mixing is done solely by the melt flow through flow regulating elements inside the mixer, which is placed in front of the machine nozzle.
With an optimal mixture, color inhomogeneities are eliminated leading to less needed color.
Static mixers are adapted to the injection volume of the machine. Therefore, a lowest possible pressure loss and energy input can be realized. All this can be realized with an excellent melt homogeneity independent from the through put. The product quality can be highly improved by the usage of a static mixer.
The flow regulating elements in the
static mixer lead to a homogeneous melt
temperature.
Static Mixer
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DiagBes
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Dec 2, 2021
In addition to dimensions, technical drawings often contain symbols (symbols) with values.
By this, the tolerance of important geometric properties or relationships is represented. This is used to describe permissible deviations.
The straightness tolerance specifies a maximum deviation of the contour at a certain point of a molded part.
Tolerated elements can be straight lines or axes.
The measured deviation at any point of the real component must not exceed the Tolearnz value displayed together with the symbol.
For a measuring point on a surface toleranced with straightness, it applies that this point must lie within a distance of two straight lines.
The distance between the two straight lines is determined by the specified tolerance value.
In this case, surfaces can be straight in the X-axis even though they are curved along their Y-axis.
The axis of a cylinder may deviate from its position by a specified tolerance value.
This deviation may only be cylindrical and is called ‘straightness tolerance of an axis’.
This drawing entry is regulated in the ISO 1101 standard or, for North America, in the Geometric Product Specification standard ASME Y 14.5.
Quality assurance: Example of the
tolerance specification on a cylinder axis (incl. meaning)
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
