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.
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.
Related topics:
Quality
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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
Related topics:
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
Related topics:
Quality
DiagBes
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
