How to adjust the appearance of injection molded products?
Shawl, also known as flying edge, overflow, overflow, etc., mostly occurs in the parting position of the mold, such as: the parting surface of the mold, the sliding part of the slider, the crack of the insert, the pores of the top rod, etc. If the spill is not solved in time, it will further expand, resulting in partial collapse of the imprint mold, resulting in a permanent obstruction. Insert cracks and the cape of the pores of the ejector bar can also cause the product to get stuck on the mold, affecting the mold release.
The natural color of the shawl is the gap between the plastic material entering the mold mating part, and the excess left on the product after cooling. The solution to the problem of the edge is simple, that is, to master not to let the melt into the mold fit gap. The plastic melt enters the mold matching gap, generally there are two situations: one is that the mold matching gap is originally large, and the colloid is easy to enter it; Another situation is that the mold matching gap was originally small, but it was forced to enter due to the pressure of the molten colloid.
On the surface, it seems that the chip can be completely solved by strengthening the production accuracy and strength of the mold. It is completely necessary to improve the production accuracy of the mold, reduce the matching gap of the mold, and prevent the molten colloid from entering. But the strength of the mold, in many cases, can not be infinitely strengthened, strengthened to any pressure, the colloid can not break into it.
The occurrence of the piercing is due to both mold and process reasons. Check the process reasons, mainly check whether the clamping force is sufficient, and only check the mold cause when the clamping force is sufficient, the blade still occurs.
Ways to check if the clamping force is sufficient:
1) Gradually increase the injection pressure, with the increase of injection pressure, the pier also increases accordingly, and the edge is important on the parting surface of the mold, 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 blade on the parting surface dissipates, or when the injection pressure is increased, the blade on the parting surface no longer increases. It is felt that this clamping force value is sufficient.
How to check if the accuracy of mold production is caused by the edge:
With a lower material temperature, a lower filling speed, and a lower injection pressure, the product is just filled (the product shrinks slightly). At this time, it can be felt that the ability of the melt to break into the mold matching gap is very weak, and if the edge occurs at this time, it can be judged that it is a problem of mold production accuracy and needs to be solved by mold repair. It can be considered to abandon the use of technological methods to solve the occurrence of the cape. It should be noted that the above "three low" premise is not less, high material temperature, faster filling speed, higher injection pressure, will cause the pressure of the mold cavity part to increase, strengthen the ability of the melt to protrude into the mold matching gap, expand the mold and occur the edge, it is true that the product is not satisfied with the glue at this time.
The analysis of the cause of the occurrence of the cape is based on the premise that the clamping force is sufficient, and when the clamping force is not timely, it is difficult to analyze the cause of the occurrence of the cape. The anatomy below is based on the condition that the clamping force is sufficient. There are several situations in which the Credential Blade occurs, and the Blade may occur for the following reasons:
The first situation: As mentioned above, in the case of low temperature, low speed, and low pressure, when the product is not satisfied with the glue, the edge has already occurred. The important reasons that may occur are: the mold production accuracy is not enough, and the matching gap is too large;
The second situation: when the product is just full, some of them have signs of shrinkage, and no edge occurs; When the injection pressure is increased and the part of the improved product shrinks, the edge occurs. Possible causes are:
1) The material temperature is too high. The material temperature is too high, the viscosity of the melt is low, the behavior is good, and the stronger the ability of the melt to break into the mold matching gap, it will cause the occurrence of the edge.
2) The injection speed is too fast, and the injection pressure is too large (resulting in oversaturation). Too fast speed, too much injection pressure, especially too large injection pressure, will strengthen the ability of the melt to penetrate the mold matching gap, resulting in the occurrence of a blade.
3) The behavior of plastic is too high. The better the behavior of the plastic, the lower the viscosity of the melt, and the stronger the ability of the melt to drill into the matching gap of the mold, and the more likely it is to strike. When the mold making has been realized, the depth of the exhaust groove of the mold, and the matching gap of the mold have been finalized, and another plastic with good behavior is produced, the edge will occur.
4) The strength of the mold is not as good as that. When the planned strength of the mold is not timely, when the mold cavity encounters the pressure of the plastic melt, it will deform and expand, and the colloid will protrude into the gap of the mold and cause a strike.
5) Product plans are different. The rubber position of the product part is too thick, and excessive compression during injection molding will cause partial shrinkage. In order to adjust the problem of partial shrinkage of the product, it is necessary to use higher injection pressure and longer injection molding time to fill and hold the pressure, and as a result, the mold strength is not as good as deformation, and the edge occurs.
6) The mold temperature is too high. High mold temperature can not only keep the plastic in good manners, the pressure loss is small, but also reduce the strength of the mold, which will also cause the occurrence of the edge.
The second situation is that the problems encountered in injection molding production cannot be solved by all technological means, which is very troublesome for injection molding technicians. In this case, it is very important to solve it by modifying the mold. The workarounds are:
1) Product part of the glue reduction. After the shrinking part of the product is reduced, the product shrinkage problem can be improved, the injection pressure will be reduced, the mold deformation will be small, and the edge can be suppressed. This is a short-term and often effective, not always used method.
2) Increase the glue inlet point. Increasing the pouring point can reduce the injection molding process, low injection pressure, the pressure of the mold cavity will be reduced, and the occurrence of the piercing can be effectively solved. Increasing the sinking point, especially at the shrinkage position of the product, can have an immediate effect on the injection pressure of the low drop cavity. It is also one of the more commonly used means.
3) Strengthen the mold part. Occasionally, the deformation of the template can be strengthened by adding a brace between the moving template and the thimble plate.
