Injection molding refers to the use of injection molding machines to plastic heat and melt, and then injected into the molding mold cavity molding, cooling and cooling, melt solidification after mold release, injection molding machine injection molding products.
In the process of injection molding into a mold may generate flash (also known as overflow edge, burr, burr, etc.), flash occurs mostly in the mold's separation position, such as the dynamic mold and the static mold's parting surface, slide the slider Matching parts, gaps in the inserts, holes in the top bar, etc. The flashing is largely due to the failure of the clamping force of the mold or the machine table. Some specific reasons are summarized as follows:
1. The maximum clamping force of the machine is not enough. The machine with sufficient clamping force should be used. The clamping force of the clamping machine wears or the wear of the clamping cylinder sealing element drops to cause the drop of clamping force. The heating system loses control and causes the actual If the temperature is too high, check the thermocouple, heating coil, etc. if there is a problem.
2, There are several situations and solutions for generating 'flash':
(1) The mold cavity disequilibrium or parallelism is not enough to cause local flash due to unbalanced force, local dissatisfaction, flow path should be placed in the center of mass symmetry without affecting the integrity of the part.
(2) The moving parts in the mold will cause flashing when the sliding core is unbalanced.
(3) When the mold is poorly vented, the compressed air will expand the parting surface of the mold and cause flashes. A good exhaust system should be set up, or the exhaust groove should be dug on the parting surface.
3, plastic fluidity is too large, or add too much lubricant, should be appropriate to reduce the pressure, speed, temperature, etc., reduce the amount of lubricant used, if necessary, use low-flow plastic.
4, processing, adjustment:
(1) The set temperature, pressure, and speed are too high. Sub-injection should be used. Injection time, pressure holding time, and excessive feeding amount will cause flashing.
(2) When adjusting, the clamping force of the clamping machine is not straightened or opened. The mold adjustment nut often moves during clamping and causes insufficient flashing due to insufficient clamping force.
(3) The degree of parallelism between the adjustment head and the two poles is not enough or the system pressure is too high.
5. Reasons for recurring flashes and parts dissatisfaction:
(1) Uncertainty in the size of plastic raw materials will make the amount of feed uncertain.
(2) The rubber head of the screw has excessive wear of the rubber ring and the rubber gasket, which may cause the molten material to flutter or dissipate between the screw and the inside of the barrel.
(3) The cooling system at the inlet fails and the feed is adjusted.
(4) The filling amount set by the barrel is insufficient, that is, if the cushion is too small, the shot will be sputtered or dissatisfied.