Multi-mode plastic flow imbalance will cause abnormal product size. For injection-molded plastic parts, controlling the flow balance of each plastic hole is the top priority. Improper plastic glue removal will affect the quality of plastic.
The causes of the impact of unbalanced glue are divided into two categories:
1, and the mold size processing error causes .
2, plastic is sheared in injection molding to .
In mold production, the error of the injection molding unevenness of the product is controlled below 8% as an acceptable range state. Exceeding and forming of the eight-mold mold will produce two different properties of plastic fluidity, sixteen-mold mold will produce four different properties of plastic fluidity, and thirty-two-mold mold will produce eight different properties of plastic fluidity. Each mold injection molding will produce several sets of different qualities after injection molding due to these different properties of plastic fluidity, which will affect the product forming size from the surface.
The following method to calculate the imbalance rate of plastic injection molding (processing reasons, plastic flow shear reasons) using the two plastic flows of eight-mode hole products:
1: Calculate the imbalance percentage of mold size processing reasons.
Calculation prerequisite: Do not fully press the product when injection molding, do not injection mold in segments, do not set the pressure holding pressure and pressure holding time, it is advisable to mold the product to be about 80%.
Take the eight-mode product in the figure as an example, which produces two plastic flows: the blue color of the label product (A1, B1, C1, D1) is one, and the second type is black (A2, B2, C2, D2)
calculates the percentage of processing abnormalities. We need to calculate the two percentages, first mark and weigh 80% of the injection molded products according to the mark. Assuming that the first type D1 has the heaviest weight and B1 has the lightest weight, then we calculate (1-(B1 has the lightest weight/D1 has the heaviest weight)) × 100%) through the calculation percentage formula to obtain the first error percentage.
Similarly, the second method is also derived according to its method.
If the error is greater than 8%, it is necessary to re-test the processing size of each mold hole and whether the cooling is uneven, and change the runner and gate size to improve the flow imbalance.
2: Calculate the percentage of imbalance caused by plastic shearing
Similarly, the eight-mode hole in the above figure, the product injection molding is about 80%. The calculation method is to use average lightest weight ÷ each average heavyweight to obtain its imbalance percentage. Assuming that the first type is heaviest average and the second type is lightest average, the calculation percentage formula is:
(1-(A2+B2+C2+D2/4)/(A1+B1+C1+D1/4))×100%
calculates its imbalance percentage.
The imbalance caused by the shear effect of plastic injection molding is difficult to solve in my personal work, and it cannot be improved through mold processing and modification. If you have experience in this area, please leave a message and learn together.
The above screenshot is a simple PPT I made for my previous colleagues to learn from. If you have friends in need, you can send it to you privately.
This is a former colleague today. I contacted me on WeChat and asked how to determine the unbalanced method of mold glue. He got the knowledge points in this area when interviewing with model engineers. Fortunately, I just understand a little in this regard. I used it in my work, but I am not using it now. I happened to have not updated my mold articles during this period and share my experience with everyone. I hope it can help some friends who are engaged in molds.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-