Tips for process optimization in injection molding

By observing a few points, you can achieve a stable and high performance in the production process. We support you with our tips for process optimization in injection molding:

Weight fluctuations in the melt cushion between the plasticizing screw and the mold can jeopardize stable processes in the production sequence. Possible weight fluctuations and the overall process can be monitored by controlling the melt cushion. Unsuitable process settings – such as an insufficient holding pressure level or time – or wear on the plasticizing screw are the most frequent causes of melt cushion fluctuations.

• Decompression after plasticizing should be set to between 2-15% of the screw diameter, depending on the type of non-return valve.

• Check the non-return valve, screw and plasticizing barrel for possible signs of wear.

• Check the closing behavior of the non-return valve; the closing behavior can be improved by adjusting the decompression after plasticizing.

• Melt cushion fluctuation can be eliminated by using a plasticizing unit that exactly matches the material.

• If you notice feeding problems during plasticizing, the barrel heating temperature must be adjusted to avoid bridging during material intake.

This section contains tips for process optimization in injection molding that relate to the optimization of incompletely filled parts. This refers to injection molded parts whose outer contours are not completely formed. Incompletely filled parts are injection molded parts whose outer contours are not completely formed. This issue occurs particularly frequently with long flow paths or in thin-walled areas (for example ribs). If mold venting is inadequate, the problem can also occur at other locations.

• Check that the injected plastic volume (for example, the shot volume) is not too low in relation to the parts weight.

• Make sure that the injection pressure and injection speed of the injection molding machine are sufficient and that there is a residual melt cushion.

• The use of digital solutions from the ENGEL iQ product family makes it possible to increase part repeatability and compensate for various process fluctuations.

The primary goal of our customers is always to strive for low cycle times. To do so, we recommend regularly checking whether it is necessary to set maximum values for process stability. This is because maximum settings mean a correspondingly higher use of energy and place a greater load on the wear parts. Maximum values are always useful if the cycle time can be significantly reduced as a result.

• Work with parallel motion to shorten the cycle time – simultaneous or synchronized movements save time: for example, you can start the peripheral solutions while the mold is still opening.

• Check the mold opening strokes and set mold opening to the required minimum.

• Use the entire cooling time for the plasticizing process to ensure gentle processing of the material and minimize wear.

• Reduce the screw speed during melt preparation – the energy requirements and material stress are also greater at higher speeds.