（48） Wire drawing Injection Molding Process Defect Handling Manual (65 types)

(1) What is wire drawing (appearance)
Wire drawing refers to a phenomenon where the front end of the main flow path does not break and extends into a filiform shape. The biggest problem is that sometimes formed products cannot fall off due to wire drawing, and the biggest problem is that sometimes formed products cannot fall off due to wire drawing, and are caught by the mold, resulting in continuous forming failure.
The better the spinnability of the resin (the ability to elongate into filaments when drawn in a molten state), the more serious the drawing. Therefore, non reinforced materials are more likely to cause wire drawing than modified materials.
(2) Causes of wire drawing
(2-1) The front end of the main channel has not been solidified yet
After injection, after the cooling process, the main flow path will solidify with the product, but because its front end is connected to the barrel nozzle, maintaining a certain temperature, sometimes the core is not fully solidified. If the mold is opened at this time, a material with good spinnability (which stretches into a filament shape and does not break when stretched) is prone to wire drawing at the front end of the main flow path.
In terms of molding conditions, if the resin temperature (especially the nozzle temperature) or mold temperature is too high, it is easy to cause wire drawing.
(2-2) Problems inherent in materials and grades
As we all know, liquid crystal polymers and impact resistance grades that have used certain elastomers are more likely to cause wire drawing than other materials. This is because these materials have good spinnability. In addition, for the same material, the lower the viscosity, the easier it is to wire draw.