Differences in wall thickness cause changes in the speed of the melt front.
This can lead to air traps, weld lines, e.g..
To get a well balanced, homogenous flow behavior, increasing local wall thickness, called flow leaders, can speed up the flow front in a specific area.
The measure of a material’s resistance to the penetration of another (harder) body is called hardness.
In the plastics industry, hardness is used to evaluate the strength and resistance of a material. There are various measurement methods, including Shore hardness, Vickers hardness and Rockwell hardness, each of which measures different aspects of material properties. Hardness testing is important to determine the suitability of plastics for specific applications, particularly in areas where wear resistance and mechanical strength are critical.
Hardness values are often expressed in numbers, with higher values indicating harder materials.
The determination of hardness is a key aspect of material testing and development in the plastics industry.
One important characteristic to determine the quality for injection molding production is the pressure inside of the cavity.
The pressure can be detected using pressure sensors that measure either directly or indirectly.
An advantage of the indirect sensors is the positioning in the clamping plate of the mold (ejection side).
There is no need for maintanance or removing the sensors if the mold is disassembled for service.
Therefore, the risk of violating the wires of the sensor is more or less zero. Both Sensor and wires are protected by the pressure plate and a stainless steel cover.
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Plastics can absorb varying amounts of moisture during storage. Depending on the plastic used, the degree of moisture must be measured before production and reduced by drying if necessary.
If a sample is heated by means of infrared radiation when measuring residual moisture, this is referred to as infrared residual moisture measurement.
The measuring principle is as follows:
A sample is heated by infrared rays. This evaporates the moisture from the plastic. By checking the weight with a precision scale built into the measuring device, the difference in weight before and after drying is determined.
This result corresponds to the moisture content in %.
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The display of the injection molding process in the theory is called injection molding simulation.
In the early development of a project, it is used to check and optimize geometry, process and mold.
This way, different versions can be tested at low costs in order to use the best version for the mold.
The optimization of the process during simulation helps to use less materials for the trials and saves time.
Also for the error analysis, the injection molding simulation can be used to find the parameters with the most influence, for example with the help of a DoE.
