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Causes and solutions for the "flash" of injection molded products

Injection molding products refer to the products which are plasticized and melted by injection molding machine, then injected into the cavity of the molding die, cooled by cooling, melted and solidified, and molded by injection molding machine.

In the process of injection molding into a mold, flash edges (also known as overflow edges, burrs, burrs, etc.) may occur, and most of the flash edges occur at the separation position of the mold, such as the parting surface of the movable mold and the static mold, and the sliding of the slider The matching part, the crevice of the insert, the hole of the ejector pin, etc., the burr is largely caused by the failure of the clamping force of the mold or the machine. Summarized some specific reasons, as follows:

"flash" of injection molded products

1. The highest clamping force of the machine should be enough to use the machine with sufficient clamping force. The clamping machine wears or the clamping cylinder seal element wears and drops or recirculates, causing the clamping force to decrease. If the heating system is out of control and the actual temperature is too high, check whether there are any problems with the thermocouple or heating coil.

2. Several situations and solutions for generating "flash":

(1) If the mold cavity is unbalanced or the parallelism is insufficient, the partial force is caused by the unbalanced force, and the local burrs are partially dissatisfied. The flow channel should be placed in the center of mass symmetry as much as possible without affecting the integrity of the workpiece.

(2) When the movable member and the sliding core in the mold are unbalanced, they will cause flash.

(3) When the mold is exhausted, the compressed air will expand the parting surface of the mold and cause flashing. A good exhaust system should be opened, or the exhaust groove should be dug on the parting surface.

3, plastic fluidity is too large, or add too much lubricant, should properly reduce the pressure, speed, temperature, etc., reduce the amount of lubricant used, if necessary, use low-flow plastics.

4. Processing and adjustment:

(1) If the set temperature, pressure and speed are too high, segmental injection should be used. Excessive injection time, dwell time, and too much feed will cause flash.

(2) When adjusting, the hinge of the clamping machine is not straightened, or the mold nut is often moved when the mold is opened or locked, and the clamping force is insufficient to cause flashing.

(3) The parallelism of the adjustment head and the two poles is insufficient or the system pressure of the adjustment is too large.

5. Reasons for repeated occurrences of flashing and manufacturing dissatisfaction:

(1) When the particle size of the plastic raw material is unevenly distributed, the amount of the added material may be indefinite.

(2) The wear of the rubber head, the rubber ring and the rubber gasket of the screw is too large, so that the melt may slide or return between the screw and the cylinder to cause flash or dissatisfaction.

(3) The cooling system of the inflow port is invalid, so that the feed is adjusted.

(4) The amount of shots set by the barrel is insufficient, that is, if the cushion is too small, there will be a lot of burrs or dissatisfaction of the parts.

Causes and solutions for the "flash" of injection molded products