How to improve the appearance of floating fibers on the surface of nylon and glass fiber

1 Reasons for the phenomenon of "floating fibers"

①Difference in density between glass fiber and base material

During the flow of plastic melt, due to the difference in fluidity and density 

between glass fiber and resin, the two tend to separate. 

The glass fiber floats to the surface and the resin sinks to the inside.

②Poor compatibility between glass fiber and nylon

Since the plastic melt is affected by the frictional shear force of the screw, nozzle, runner 

and gate during the flow process, it will cause local viscosity differences and at the same time destroy 

the interface layer on the glass fiber surface. The smaller the melt viscosity, the smaller the interface layer. 

The more seriously the layer is damaged, the smaller the bonding force between the glass fiber and the resin.

 When the bonding force is small to a certain extent, the glass fiber will break free from the constraints of the resin 

matrix and gradually accumulate toward the surface and be exposed.

③Fountain Effect

When nylon melt is injected into the mold, a "fountain" effect will be formed, that is, the glass fiber

 will flow from the inside to the outside and contact the surface of the mold cavity. 

Due to the low temperature of the mold surface, the light-weight, fast-condensing glass fiber will be instantly frozen. .

Therefore, the formation of the "floating fiber" phenomenon is not only related to the composition and 

characteristics of plastic materials, but also to the molding process, which has great complexity and uncertainty.

2.The solution to "floating fiber" appears

①Mold aspect

The appearance of the product is deliberately made into a matte or etched surface.

②Improve the compatibility between glass fiber and nylon

Add additives such as compatibilizer, dispersant and lubricant to the molding material, 

including silane coupling agent, maleic anhydride graft compatibilizer, fatty acid lubricant and 

anti-glass fiber exposure agent, etc., to improve the relationship between glass fiber and resin.

It improves the compatibility, improves the uniformity of dispersion, increases the interface bonding strength, 

and reduces the separation of glass fiber and resin.

3 Improve molding process conditions

① Increase filling speed

② Increase mold temperature

③ Reduce the temperature of the screw metering section and reduce the amount of sol