How do plastic mold manufacturers deal with white edges?

How do plastic mold manufacturers deal with white edges? Generally speaking, the first consideration for people who do not understand this profession is to change the material. Why do you say that? Because this is a method that many people who do not understand plastic injection processing know, but this method has a flaw, that is, it is spoiled. Is there no other solution for refueling? So how is the white border formed?
The white edge is a unique injection defect of modified polyethylene and plexiglass, and it mostly appears on the edge of the part close to the parting surface. The white border is a collection of many stretch-oriented molecules that are straight to the direction of the material flow and the fine spaces between them. There is still a polymer connecting phase in the direction of the white edge, so the white edge is not a crack. Under proper heating, it is possible that the stretch-oriented molecules will return to their natural bending state and the white edge will decay.
Solutions for plastic mold manufacturers:
During the production process, attention should be paid to the tight fit of the parting surface of the template, especially the area around the cavity, which must be under a truly sufficient clamping force to prevent longitudinal and lateral expansion.  
Decrease injection pressure, time and material quantity, and reduce molecular orientation. 
Applying oil-based release agent to the white edge of the mold surface, on the one hand, makes it difficult to transfer heat and maintains a higher high temperature at all times, and on the other hand, it may suppress the white edge to reduce the appearance of the white edge.
Warpage and deformation of plastic injection molded products is a very troublesome problem. It should be dealt with mainly from the aspect of mold planning, while the adjustment effect of molding conditions is very limited. So, how do we deal with the warpage and deformation of plastic injection molded products?
1. When poor demolding causes stress and deformation, it can be dealt with by increasing the number or area of ​​push rods and setting demolding slope.
2. When the residual stress is deformed due to the molding conditions, the stress can be eliminated by reducing the injection pressure, increasing the mold and making the mold temperature uniform, increasing the resin temperature or using annealing methods.
3. The cooling method can be adjusted and the cooling time can be prolonged when the cooling method is not suitable and the cooling is uneven or the cooling time is insufficient. For example, the cooling circuit can be arranged as close as possible to the deformed place.
4. Regarding the deformation caused by the shortening of the molding, the mold plan must be revised. Among them, the most important thing is to make the product wall thickness common. Sometimes, as a last resort, the deformation of the product has to be measured, and the mold is trimmed in the opposite direction for correction. Resins with larger shortening rates are generally crystalline resins (such as polyoxymethylene, nylon, polypropylene, polyethylene and PET resins) than non-crystalline resins (such as PMMA resin, polyvinyl chloride, polystyrene, ABS resin, etc.) The deformation of AS resin, etc.) is large. In addition, because the glass fiber reinforced resin has fiber orientation, the deformation is also large.


Post time: Apr-25-2021
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