Injection molding

Trouble name
Appearance
The resin is not completely molded in the desired shape at the rib, boss, tip, and the like.
Excessive film is formed as the resin is flowed into the gap between the fixed and the mobile types, slide part and gap of the insert, interval of the ejector pin.
The surface of the product has shrank in the thickness direction, especially near the rib.
Flow mark is formed on the part surface, especially near the gate and the final filling area.
Silver streak is formed on the surface.
A cloudy mark is formed on the part surface.
Weldline marks can be visually observed for molded parts.
Bubble is formed on the inside/outside of the molded part.
Void mark is formed in the inside/outside of molded part.
Black streak and brown striation are formed on the part surface.
Stress is generated by the high viscosity at the boundary of the solidifying and the melted layers because of the difference in the cooling rate caused by the difference in the thickness of molded part.
The skin layer of molded parts can be strippeded-off. Mainly occurs at the gate position of molded parts and is predominant for parts. The molded part is composed of overlapped multi-layer which can be stripped-off layer by layer when peeled.
The polyaer melt that passed through the gate is solified with the shape of a snake as it progress to the end of the parts.
Molded part shows warpage or twisting.
Severe noise when opening /closeing the mold
Noticeable difference between the "standard" and part color.
The surface of molded part has poor gloss.
Some areas of the product are discolored to white.
When molded part is ejected from the mold, it is cracked and whitened due to excessive force.
The ejector pin mark is left on the molded part(whiteening, crack or deformation)
The part is physically damage while removing from the mold.
Dark brown color residues are formed on the mold surface. The mold surface has been oxidized and has a poor gloss due to the accumulation of gas and other foreign materials.
Ring is formed around the gate, specially for ABS resin.
The weight of the molded parts varies.

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