Injection molding product solutions such as flying edge, overflow edge, overflow material

Most of the injection molding products with flying edge, overflowing edge and overflowing material occur in the parting position of the mold, such as: the parting surface of the mold, the sliding part of the slider, the gap of the insert, the hole of the top bar, etc.. The overflow material will be further expanded if not solved in time, thus forming local collapse of the embossing mold and causing permanent damage. The flying edge, overflowing edge and overflowing material in the gap of the insert and the hole of the top bar will also make the products stuck on the mold and affect the demoulding.

Injection molding products flying edge, overflow edge, overflow, overflow material is essentially plastic material into the mold with the gap between the parts left on the product after cooling excess material. To solve the problem of phi front is very simple, that is to control not to let the melt into the mold fit-gap to go.


Plastic melt into the mold with the gap to go, there are generally two cases: one case is the mold with the gap is originally large, the gel is easy to enter it; another case is the mold with the gap was not large, but because of the molten gel under pressure forced into the.

On the surface, it seems that the flying edge, overflowing edge and overflowing material can be completely solved by strengthening the manufacturing precision and strength of the mold. Improve the manufacturing accuracy of the mold, reduce the mating gap of the mold, to prevent the molten gel into, completely necessary. However, the strength of the mold, in many cases, can not be strengthened indefinitely, strengthened to any pressure, the gel can not burst into it.

The production of injection molded products with flying edges, overflowing edges and overflowing materials has both mold-related and process-related reasons. To check the cause of the process, the first thing to check is whether the clamping force is sufficient, and only check the cause of the mold if the clamping force is sufficient.

The method to check whether the clamping force is sufficient.

1) gradually increase the injection pressure, with the increase of injection pressure, injection products flying edge, overflow edge, overflow material also correspondingly increased, and the phi front is mainly in the mold parting surface, indicating that the clamping force is not enough.

2) Gradually increase the clamping force of the injection molding machine, when the clamping force reaches a certain value, the phi-front on the parting surface disappears, or when the injection pressure increases again, the flying edge, overflowing edge and overflowing material on the parting surface also no longer increases. Then the clamping force is considered sufficient.

Check whether the mold manufacturing precision causes the injection molding product flying edge, overflowing edge, overflowing material method.

With lower material temperature, lower filling speed and lower injection pressure, the product will be just full (the product has slight shrinkage). At this time, it can be considered that the ability of the melt to burst into the mold with the gap is very weak, at this time, if the phi front is generated, it can be judged that the mold manufacturing precision problems, need to repair the mold to solve. You can consider giving up the process to solve the injection molding products with flying edge, overflow edge, overflow material generation.

It should be noted that the above "three low" conditions are indispensable, high material temperature, faster glue filling speed, higher injection pressure, will lead to increased local pressure in the mold cavity, enhance the ability of the melt to burst into the mold with the gap, expand the mold and produce injection molding products flying edge, overflow, overflow material, although the product is not full of glue.

The analysis of the reasons for the production of flying edge, overflowing edge and overflowing material is based on the premise that the clamping force is sufficient, when the clamping force is insufficient, it is difficult to analyze the reasons for the production of phi. The following analysis is based on the case of sufficient clamping force, please note that the reader.

According to the several situations in which the flying edge, overflowing edge and overflowing material appear, the flying edge, overflowing edge and overflowing material may arise.

The first situation.

As mentioned above, in the case of low temperature, low speed and low pressure, when the product is not full of glue, flying edge, overflow and overflow have been produced. The main reason may be generated: the mold manufacturing precision is not enough, with too much clearance;

The second situation.

When the product is just full of glue, there is local shrinkage phenomenon, no phi; when the injection pressure is increased to improve the product local shrinkage, the phi is produced. Possible causes are.

1) The material temperature is too high. Material temperature is too high, the viscosity of the melt is low, good fluidity, the stronger the ability of the melt to burst into the mold with the gap, it will lead to the production of phi.

2) injection speed is too fast, injection pressure is too large (resulting in over-saturation of filling). Too fast speed, too much injection pressure, especially too much injection pressure, will enhance the ability of the melt into the mold with the gap, resulting in the phi front.

3) The fluidity of the plastic is too high. The better the fluidity of the plastic, the lower the viscosity of the melt, the stronger the ability of the melt to burrow into the mold fit gap, it is easy to produce phi. When the mold production has been completed, the depth of the exhaust slot of the mold, mold fit gap has been set, change another liquidity of good plastic to produce, it will produce phi.

4) The strength of the mold is not enough. When the design strength of the mold is not enough, when the mold cavity withstand the pressure of the plastic melt, it will be deformed and swollen, the gel will burst into the gap of the mold, producing flying edge, overflow edge, overflow material.

5) The product design is unreasonable. The product local glue bit is too thick, and too much shrinkage during injection, it will lead to local shrinkage. In order to regulate the problem of local shrinkage of the product, often need to use a higher injection pressure, longer injection time to fill and keep pressure, resulting in insufficient mold strength deformation, resulting in flying edge, overflow, overflow material.

6) The mold temperature is too high. High mold temperature, not only can make the plastic to maintain good fluidity, pressure loss is small, but also reduces the strength of the mold, which will also lead to the generation of flying edge, overflow, overflow material.

The third situation.

Is the most commonly encountered problem in injection molding production, usually using all the process means can not be solved, the most troubling to injection molding technicians. For this case, the main means is to solve it by repairing the mold. The solution methods are.

1) Product localized glue reduction. The product shrinkage of the local reduction of glue, glue position thinning, product shrinkage can be improved, injection pressure will be reduced, mold deformation will be small, phi can be suppressed. This is the most effective and most commonly used method.

2) Increase the feeding point. Increase into the pouring point, can reduce the injection process, reduce the injection pressure, the mold cavity by the pressure will be reduced, can effectively solve the production of phi front. Increase into the pouring point, especially in the product shrinkage position to increase into the pouring point, to reduce the mold cavity injection pressure can play an immediate effect. It is also one of the more common means.

3) Strengthen the mold locally. Sometimes the deformation of the mold plate can be strengthened by adding a brace between the dynamic mold plate and the ejector plate.


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