1. Plastic Injection Molding Defects
Common Defects
| – Short shot – Flash – Sink marks – Warpage – Burn marks – Flow lines | – Weld lines -Air traps -Black specks – Silver streaks – Bubbles/voids – Cracks |
Major Causes
| Material Issues – Moisture contamination in resin – Incorrect resin grade – Mixed or contaminated material – Regrind ratio too high – Poor material drying | Machine Parameter Issues – Incorrect injection pressure – Low/high melt temperature – Improper cooling time – Incorrect holding pressure – Improper injection speed |
| Mold Issues – Poor venting – Worn mold cavity – Incorrect gate design – Cooling imbalance – Mold misalignment | Human/Process Issues – Wrong setup parameters – Inadequate startup verification – Poor process control – Operator handling damage |
2. Precision Plastic Component Manufacturing
| Common Defects – Dimensional out of tolerance – Surface scratches – Deformation – Burrs – Cosmetic defects – Inconsistent dimensions | Major Causes – Tool wear – Poor calibration – Temperature variation – Improper fixture alignment – Inadequate inspection methods – Measurement equipment error – Material shrinkage variation |
3. Mold and Tooling Production
Common Defects
- Poor mold fitment
- Flash generation
- Uneven cooling
- Premature mold wear
- Cracks in tooling
- Surface finish defects
Major Causes
| Design Problems – Weak mold structure – Incorrect runner/gate design – Poor cooling channel layout | Manufacturing Problems – CNC machining inaccuracies – EDM defects – Improper heat treatment – Poor polishing quality |
Maintenance Problems
- Lack of preventive maintenance
- Rust/corrosion
- Improper storage
- Excessive production cycles
4. Plastic Painting, Printing, and Assembly Services
| Painting Defects – Peeling – Orange peel – Uneven coating – Dust contamination – Color mismatch – Paint blistering | Causes – Poor surface cleaning – Incorrect paint viscosity – Humidity contamination – Improper curing temperature – Dirty paint booth – Static electricity |
| Printing Defects – Smudging – Misalignment – Ink fading – Incomplete print | Causes – Incorrect ink curing – Fixture instability – Operator setup error – Poor surface treatment |
| Assembly Defects – Loose fitting – Wrong component assembly – Broken clips/tabs – Missing parts | Causes – Human error – Incorrect work instruction – Poor poka-yoke system – Excessive assembly force – Inadequate training |
5. High-Precision Industrial Plastic Products
Common Defects
- Micron-level dimensional variation
- Optical defects
- Functional failure
- Connector fitting issues
- Excessive tolerance stack-up
Major Causes
Environmental Factors
- Temperature fluctuation
- Humidity variation
- Dust contamination in cleanroom
Equipment Factors
- Machine vibration
- Precision calibration drift
- Servo instability
Quality System Factors
- Insufficient SPC monitoring
- Weak incoming material control
- Poor traceability
- Inadequate preventive maintenance
Automotive Industry-Specific Critical Defects
- Safety-related dimensional errors
- Heat resistance failure
- Clip breakage
- Vibration/noise issues
- Assembly mismatch
Major causes:
- PPAP control weakness
- Poor mold validation
- Resin batch inconsistency
- Inadequate durability testing
Electronics Industry-Specific Critical Defects
- ESD damage
- Connector misfit
- Warpage affecting PCB assembly
- Cosmetic scratches
- Insulation failure
Major causes:
- Electrostatic discharge exposure
- Precision tolerance failure
- Contamination
- Cleanliness control failure
Top Root Causes Across the Industry
The most common root causes overall are:
- Improper material handling and drying
- Poor mold maintenance
- Incorrect machine parameter setup
- Inadequate operator training
- Weak process control/SPC
- Tool wear and dimensional drift
- Environmental contamination
- Lack of preventive maintenance
- Poor design validation
- Human error during assembly or inspection