Resources

Symptom: The mold cavity is not completely filled with resin.

Cause: Insufficient cushion, poor flowability, inadequate gas venting, and insufficient injection pressure/speed.

Remedy: Increase injection speed, mold temperature, and cylinder temperature, or install gas vents at the unfilled area. Switching to a material with better flowability is also effective.

Symptom: Resin overflows through gaps at product edges or the parting line.

Cause: Weak mold clamping, low clamping force setting, or excessively high cylinder temperature or internal pressure.

Remedy: Remove foreign material from mold surfaces, adjust gate thickness, or enlarge sprue/runner dimensions.

Symptom: Pre-cooled resin is injected and appears as visible defects on the product surface.

Cause: Nozzle heater temperature is too low or resin is leaking.

Remedy: Increase nozzle heater temperature, reduce back pressure to prevent resin dripping, and optimize gate design.

Symptom: Gas trapped at the end of resin flow is compressed under high pressure and overheats, burning the resin.

Cause: Absence of gas vents or excessively high injection speed.

Remedy: Optimize (or clean) the mold gas venting system, and reduce injection speed and injection pressure.

Symptom: Internal voids formed during shrinkage in thick-walled sections.

Cause: Ineffective holding pressure or resin stagnation due to improper gate positioning.

Remedy: Avoid abrupt wall thickness transitions, position the gate at the thickest section, and ensure adequate holding pressure time.

Symptom: V-shaped grooves or lines form where two or more resin flow fronts meet.

Cause: Formed when resin flows converge from multiple directions; these areas exhibit reduced strength.

Remedy: Relocate the weld line by adjusting gate position or wall thickness, fine-tune mold/cylinder temperature and injection speed, and reinforce the venting system.

Symptom: Repetitive circular or wave patterns appear near the gate or at the flow end, resembling record grooves.

Cause: Cylinder and mold temperatures are too low, or injection speed is too slow.

Remedy: Increase cylinder and mold temperatures, increase injection speed, and add more gates or enlarge gate dimensions.

Symptom: The surface of the molded part forms multiple layers and peels off.

Cause: Caused by high shear stress, or contamination of masterbatch and raw materials with foreign substances.

Remedy: Increase cylinder temperature, reduce injection speed and holding pressure, and prevent raw material contamination.

Symptom: Gloss levels appear inconsistent across different areas of the textured surface.

Cause: Caused by abrupt thickness changes, insufficient holding pressure, undersized gates, or low cylinder/mold temperatures.

Remedy: Position the gate at the thickest section, increase mold/cylinder temperature, and increase injection speed.

Symptom: The surface lacks gloss, feels rough, and glass fibers protrude visibly.

Cause: Occurs when mold temperature, injection speed, or cylinder temperature is too low.

Remedy: Increase mold and cylinder temperatures and apply higher injection speed.

Symptom: Silver or black streaks appear on the surface of the molded part.

Cause: Resin degrades due to overheating or prolonged residence in the cylinder, or overheats from gate shear friction.

Remedy: Reduce injection speed, metering speed, back pressure, and cylinder temperature to prevent overheating.

Symptom: Resin is injected directly without resistance, creating snake-like flow marks.

Cause: Improper gate positioning and excessive injection speed.

Remedy: Reposition the gate so resin first impinges on the mold wall, install auxiliary cores, and reduce injection speed.

Symptom: Localized depressions appear on the surface of the molded part.

Cause: Caused by inadequate holding pressure, improper gate positioning, or abrupt thickness variations.

Remedy: Increase holding pressure and holding time, optimize rib thickness to 0.5x or less of the base wall thickness, and relocate the gate to the thickest section.

Symptom: Ejector pin marks or punctures appear on the surface, causing damage.

Cause: Insufficient ejector pin count/size, undercuts, overpacking, or excessive ejector speed.

Remedy: Increase the number and size of ejector pins, increase draft angles, and extend cooling time to reduce part stress.

Symptom: Resin gas or additives accumulate on the core or venting system.

Cause: Excessive cylinder temperature, high injection speed, and insufficient venting.

Remedy: Reduce cylinder temperature and injection speed, improve the gas venting system, and ensure thorough pre-drying.

Symptom: The molded part fails to remain flat and twists or warps.

Cause: Caused by localized shrinkage variations, mold surface temperature differences, and glass fiber orientation (anisotropy) differences.

Remedy: Design uniform wall thickness, optimize cooling circuits for uniform temperature, and adjust gate position considering glass fiber orientation.