Tutorial moldflow simulation and analysis.

Here is a moldflow simulation tutorial for Autodesk Moldflow Insight which is the injection molding simulation software we use.
It will show what a fill+pack analysis can look like at our simple box.

01. Choice of material.

ABS plastic was selected from SolidWorks material database during the plastic part design earlier.
There is no need to change material so we continue with ABS plastic in the injection molding simulation.

02. Fill+pack analysis.

We start by looking at the fill pattern when the box is injection molded.
Please show us the fill pattern in the moldflow fill+pack analysis.

03. Analysis result.

The fill pattern is as expected.
First the long sides of the box are filled, then the short sides and finally the corners.
The injection pressure will be higher on the long sides of the box (290 Bar) than on the
short sides (180 Bar) and the corners (115 Bar) because the fill pattern is unbalanced.
This may cause our box to be of unnecessarily poor quality.

04. Flow leaders.

By adding flow leaders to the injection molding tool for the box, we can balance the fill pattern significantly.
Show me how to add flowleaders to the injection molding tool.

05. New analysis result.

After the flow leader adjustments, the fill pattern on the box is almost balanced.
Actually, it is now the short sides that fill first even if the difference is very small.
The injection pressure is now higher on the short sides of the box (120 Bar) than on the
corners (90 Bar) and the long sides (70 Bar) because the fill pattern is close to being balanced.
The injection pressure required to fill the box is now 540 Bar instead of 750 Bar.
It is a pressure decrease of 210 Bar or 39%.

06. Result side by side.

Please show us the new analysis result side by side.

07. Simple design change.

Thanks to the simple change in the design of the box, it can now be injection molded with a balanced filling pattern and thus a lower pressure.
The quality of the box becomes better when the shear stress is reduced.
In addition we might be able to produce in smaller and cheaper injection molding machines.

Keep in mind that flow leaders can be added retroactively because steel should be removed from the mold.
Material consumption is likely to increase.
Also, do not increase the wall thickness more than about 25% and the wall thickness change must be gradual.
As the wall thickness increases, the cycle time might increase if the cooling time is affected.

08. Bonus - Thermoset analysis.

Do you work with molds for rubber parts (thermoset) it works just as well.
We will show the result of an analysis of an O-ring made of FKM with 7+7 cavities in a 3-plate or a double-deck mold.
In this way it is possible to increase productivity further by approximately 50% compared to a regular 2-plate mold.

09. 3-plate reactive molding.

The approach is to analyze the fixed side first in order to optimize the runner system while keeping the pressure requirements under control.
When the fixed side is analyzed add the moving side and increase the cross sectional area of the runner system until the filling pattern is balanced.
The film gates should be exactly the same and the cavities should be positioned exactly above each other.

10. Result.

The result can look like this.
Show me the result for 3-plate reactive molding.