Plastic Processing Terminology
* **Weld Mark/Watermark/Line/Stretch:** A mark caused by incomplete fusion at the interface of two material streams during injection molding.
* **Shrinkage Mark/Shrinkage:** A depression on the surface of a plastic part that occurs when the part cools and solidifies within the mold cavity due to uneven wall thickness, insufficient injection pressure, or insufficient cooling time.
* **Airflow Marks:** Material flow marks on the surface of a plastic part caused by pressure and flow velocity within the mold cavity, resulting from the injection mold structure, molding process, and materials.
* **Stone Marks/Punching Marks:** Silvery-white streaks formed on the surface of a plastic part by low-molecular-weight volatiles, moisture, and other gases.
* **White Marks/Whitening/Whitening/Whitening/Whitening/Whitening:** Localized white marks on the surface of a plastic part caused by external pressure, leading to rearrangement or breakage of some molecular structures.
Surface Protrusion / Height / Rise / Delay: Raised areas on the surface of a plastic part caused by uneven demolding or the action of ejector pins/plates.
Cracks / Bursts / Broken Threads / Cracks: Cracks on the surface or inside a plastic part caused by pressure, external forces, or environmental factors.
Discoloration Spots / Black Spots / Spots / Marks / Mold Marks: Spots formed on the surface of the molded plastic part due to foreign matter mixed in the raw material or excessively high temperatures during molding, resulting in carbonization of the plastic material.
Mold Marks / Mold Flaws / Mold Indentations / Mold Damage: Marks left during molding due to scratches or dents on the injection mold surface.
Flash / Burrs: Excess plastic that overflows into the mold parting surface and inserts during injection molding, leaving excess material on the plastic part after cooling.
Poor Glue Flow / Insufficient Glue: Incomplete glue flow in parts of the plastic part, failing to meet design requirements.
Uneven Color / Color Mixing: Defects resulting in uneven color on the surface of plastic parts.
Warpage / Deformation: Localized or overall deformation of plastic parts caused by internal stress.
Delamination / Peeling: Defects resulting in separation between layers.
Hole Plug / Clogged Hole / Blind Hole: Holes in plastic parts are blocked by burrs or broken needles, with more than 50% blockage.
Bubble / Bubbling / Vaporization: Bubble-like defects formed inside or on the surface of plastic parts due to residual air or other gases.
Color Mismatch / Color Difference / Darker Color / Lighter Color / Poor Gloss: The color and gloss of the plastic part do not match the standard sample.
Excess Glue: Localized areas of excess glue on plastic parts caused by defects in the molding surface of the injection mold.
Scorching / Yellowing / Blackening: Scorched appearance caused by poor venting in the injection mold leading to localized high temperatures and degradation of the plastic material; or by excessively high shear rates during the flow of the plastic material, resulting in scorching.
Fish Scale Pattern: A fish-scale-like pattern formed on plastic parts due to low mold temperature and slow injection speed.
Glue Threads/Prints: Threads of plastic material are pulled out during demolding due to high nozzle temperature, excessive back pressure, etc., adhering to the mold cavity and forming linear structures on the surface of the finished product during subsequent molding.
Mold Sticking/Glue Adhesion: The phenomenon of partial breakage of plastic parts during demolding, leaving residue in the injection mold due to excessive injection pressure, small draft angle, etc.
Water Leakage Marks: Water droplets or marks formed in the injection mold due to leakage in the injection mold channels, which are not cleaned and leave traces on the surface of the plastic parts during subsequent molding.
Ghosting: The phenomenon of overlapping light and shadow during light transmission testing caused by low injection temperature, unsaturated plastic parts, product deformation, etc.
Discontinuity: The unevenness of the surface after fitting parts, resulting in height differences.
**Gap:** Refers to the distance between mating parts (excluding the design process groove).
**White Spots/Marks:** White spots or marks formed on the surface of plastic parts due to poor quality pigments, residue left in ejector pins that is ejected during mold closing, or the presence of metal in the raw material.
**Size Too Large/Too Long:** Plastic parts are larger than required due to short injection and holding times, inconsistent raw material shrinkage rates, etc.
**Size Too Small/Too Short:** Plastic parts are smaller than required due to low injection pressure, short holding time, inconsistent raw material shrinkage rates, etc.
**Poor Assembly/Tight/Loose Trial Assembly/Tight/Loose Snap-in/Noise:** Problems such as tightness, looseness, and noise during trial assembly are caused by dimensional discrepancies between mating components. These are collectively referred to as poor assembly.
**Screw Column Bursts:** Screw columns burst or turn severely white when screwed in.
**Stripped Threads:** Screws cannot be tightened properly when driven to the specified torque.
**Screws Not Tightly Threaded:** Screws cannot be tightened properly when driven to the specified torque.
**Screws Are Too Large/Too Long:** Slip marks are dull, shallow marks on the surface of plastic parts caused by slight mechanical friction.
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