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How to solve the flash problem of injection mold in the production process

by:Vowin Rapid Prototyping     2023-02-09
Injection mold is a process equipment for all kinds of production of daily necessities. It can be seen in the fields of electronics, toys, aerospace, automobiles, medical treatment and other fields. With the development of the whole industry, the industry's requirements for molds are also getting higher and higher. It is getting higher and higher, more and more precise, and even a little bit of flaw may be eliminated.

During the injection molding process, flash (also known as overflow, burr, burr, etc.) may occur. Most of the flash occurs at the separation and closing positions of the mold, such as the parting surface of the dynamic mold and the static mold, and the sliding of the slider. Parts, insert gaps, ejector pin holes, etc., the flash is largely caused by the failure of the clamping force of the mold or machine. Why do flashes occur in the process of injection mold processing, and how to solve them? Wo Neng Precision takes everyone to see:

1. If the maximum clamping force of the machine is not enough, a machine with sufficient clamping force should be selected. The mold clamping machine hinge is worn or the sealing element of the clamping cylinder is worn, and there is oil dripping or backflow, which causes the clamping force to drop. If the heating system is out of control and the actual temperature is too high, check whether there is any problem with the thermocouple, heating coil, etc.

2. Several situations and solutions of 'flash' in injection molds:

(1) Unbalanced distribution of mold cavities or insufficient parallelism result in unbalanced force, resulting in local flash and local dissatisfaction. The flow channel should be placed in the center of mass symmetry as far as possible without affecting the integrity of the part.

(2) Flashing will be caused when the movable components and sliding core in the mold are unbalanced.

(3) When the mold exhaust is not good, the pressurized air will cause the parting surface of the mold to expand and flash. A good exhaust system should be installed, or an exhaust groove should be dug on the parting surface.

3. If the fluidity of the plastic is too large, or too much lubricant is added, the pressure, speed, temperature, etc. should be appropriately reduced to reduce the amount of lubricant used, and plastic with low fluidity should be selected if necessary.

4. Injection mold processing and adjustment:

(1) If the set temperature, pressure, and speed are too high, segmental injection should be used. Injection time, holding time, and excessive feeding amount will cause flash.

(2) When adjusting, the hinge of the mold clamping machine is not straightened, or the mold adjusting nut often moves when opening and clamping the mold, resulting in insufficient clamping force and flashing.

(3) The parallelism between the adjusting head and the two poles is not enough or the pressure of the adjusted system is too high.

5. Reasons for repeated occurrence of injection mold flash and parts dissatisfaction:

(1) When the particle size of plastic raw materials is very uneven, the amount of feeding will be uncertain.

(2) The wear of the glue head, rubber ring and rubber gasket of the screw is too large, so that the melt may slide and reflow between the screw and the barrel, resulting in flash or dissatisfaction.

(3) The cooling system at the inlet port fails, which makes the adjustment of the feed material.

(4) The injection volume set by the barrel is insufficient, that is, the cushion pad is too small, which will cause flashes or parts to be dissatisfied when the injection is more or less.
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