Problem library
Diagnose before changing the grade.
Similar defects can come from resin, processing, tooling, part design or the service environment.
01Cracking after molding or assembly
Cracks near bosses, corners, weld lines or stressed surfaces.
Possible contributors- Residual molding stress
- Moisture or thermal degradation
- Chemical stress cracking
- Material toughness mismatch
Validation pathReview drying, process history, geometry and chemical contact; then compare tougher or more stress-resistant formulations under controlled conditions.
02Drop test or low-temperature impact failure
Housing fracture, brittle clips or inconsistent impact performance.
Possible contributors- Insufficient impact modification
- Notch-sensitive design
- Cold-temperature embrittlement
- Regrind or aging effects
Validation pathDefine the real test temperature and failure location, then screen impact-modified compounds on representative molded parts.
03Flame performance does not meet the target
A candidate grade is listed, but the part or tested thickness fails.
Possible contributors- Thickness mismatch
- Color or additive interaction
- Moisture and processing damage
- Wrong certification scope
Validation pathConfirm the applicable standard, thickness and certification details before adjusting the polymer or flame-retardant system.
04Sink marks or poor surface appearance
Visible depressions, fiber read-through, gloss variation or flow marks.
Possible contributors- Wall-thickness concentration
- Packing or cooling imbalance
- Reinforcement level
- Flow and shrinkage mismatch
Validation pathSeparate tool and process effects from material shrinkage, flow and surface requirements; then optimize the full molding window.
05Warpage or dimensional instability
Flatness, fit or tolerance changes after molding or conditioning.
Possible contributors- Fiber orientation
- Uneven cooling
- Moisture absorption
- Anisotropic shrinkage
Validation pathMap gate position, flow direction and conditioning history before selecting reinforcement and shrinkage-control options.
06Imported material cost or supply risk
A technically suitable grade is expensive, delayed or single-sourced.
Possible contributors- Trade-name specification
- Over-specified properties
- Limited approved sources
- Unclear validation plan
Validation pathTranslate the incumbent grade into an application requirement, shortlist Chinese candidates and validate them through data, samples and finished-part trials.