Jun 12, 2019
The directional dependence of properties of a molded part is called anisotropy.
During processing (injection molding) the macromolecules are aligned in the direction of flow.
This results in different strengths depending on the direction.
In general, the strengths are higher in the direction of flow than at right angles to it.
Therefore, in material data sheets, information is usually given in the longitudinal and transverse directions.
Anisotropy is particularly pronounced in fibre-reinforced plastics.
Quality: Main orientation of glass fiber in the center layer of a plastic
part.
Related topics:
Fibre Orientation
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Feb 1, 2019
A useful parameter to evaluate the quality of an element is the aspect ratio.
In simulation triangular elements are the main factor in meshing the surface of a part.
The aspect ratio can be determined in different ways.
In Moldex3D for example, the aspect ratio is calculated based on two circles.
The inside circle is touching every edge of the triangle tangential, while the outer on goes through all the edges of the element.
The aspect ratio equals twice the inner radius divided by the outer radius of the circles.
An equilateral triangle has an aspect ratio of 1, a triangle with no surface area has an aspect ratio of 0.
The higher the aspect ratio, the better the quality.
In Moldflow there are different ways to calculate an aspect ratio.
Using one strategy the aspect ratio lies between 0 and 1 similar to Moldex3D.
Another strategy leads to an aspect ratio that starts by 1,16 to infinity. Hereby the smallest value represents the best quality.
Jul 31, 2019
Water is mainly used as coolant in injection molding.
It is required as cold and hot water.
If a cooling device is not connected to an external water supply, but creates cold water through an internal module, the device is called autarkic temperature control.
In this case of self-sufficient temperature control, both the water replenishment and the cooling take place independently of an on-site cooling network.
With this double benefit, a mains-independent cooling and heating process with temperatures of 20 °C to 90 °C is possible.
Higher temperatures up to 400 °C are generated electrically.
Mostly mobile, the cooling and temperature control unit can be matched in its performance to the production process and stands next to the machine(s).
Jul 17, 2019
During plasticising in injection molding process, the melt is pushed forward by the rotating screw.
The pressure that is build up in front of the screw (P1) is responsible for her backward movement.
Backpressure (P2) is needed to withstand this backwards movement of the screw for a certain time.
This is to ensure a better mixing of color and additive, better melt uniformity, and controlling shot volume.
In the process shear heat is applied to the melt as well.
A recommended range of backpressure for most plastic materials range from 20 bar to 200 bar.
PVC on the other side uses backpressures of up to 400 bar.
Injection Molding Machine: The
backpressure counteracts against the backwards movement of the screw during plasticising.
Related topics:
Screw Speed
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Nov 22, 2018
A uniform cooling of the part is important in the injection molding process in order to reduce shrinkage and warpage.
Especially in long and narrow areas, the cooling layout is often difficult.
This is because the space is insufficient to drill holes next to each other.
Therefore, when there is only enough space for one hole, it is recommended to use a baffle.
It is inserted into the hole and redirects the coolant from one side into the hole and out on the other side.
Injection Molding: The
baffle consists of a drilled hole with an inserted divider plate.
Related topics:
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
