Top 10 Common Problems and Solutions for Bathroom Plastic Parts!

 

 

1. Cracking of Plastic Parts

Cause Analysis:

Material Expansion Due to Water Absorption: Plastic materials that are not fully vitrified expand upon absorbing water, leading to internal stress accumulation (e.g., low-quality PVC).

 

Process Defects: Insufficient holding pressure during injection molding, uneven cooling, or improper mold design can easily cause internal stress cracks.

 

Improper Installation: External impact or overtightening screws during installation can lead to localized stress concentrations.

 

Solution:

Choose fully vitrified materials or modified plastics (e.g., glass fiber-reinforced PA or POM) to increase tensile strength.

 

Optimize the injection mold processing technology and use cavity pressure monitoring technology to adjust parameters in real time to reduce internal stress.

 

Use flexible fasteners (e.g., rubber gaskets) during installation to avoid hard contact that can cause cracking.

 

2. Surface Discoloration or Fading

Cause Analysis:

Ultraviolet Oxidation: Long-term exposure to sunlight can cause the pigment's lack of light resistance to decompose its molecular structure.

 

High-temperature aging: High temperatures and high humidity in bathroom environments accelerate material oxidation, especially for PP and ABS, which are prone to yellowing.

 

Chemical corrosion: Cleaners containing strong acids and alkalines can damage the surface coating or material stability.

Solution:

Select UV-resistant modified plastics and add light stabilizers (such as hindered amines) to improve weather resistance.

 

Avoid using chlorine-containing or strongly acidic or alkaline cleaners; instead, use a neutral cleaning solution.

 

Perform a salt spray test on electroplated or painted surfaces to ensure that the coating adhesion meets standards (refer to GB/T 23447).

 

3. Persistent odor

Cause analysis:

VOC release from materials: Residual monomers (such as styrene) evaporate during the processing of low-quality PVC or recycled materials.

 

Mold growth: In humid environments, the pores on the surface of plastic parts harbor dirt and grime, breeding microorganisms and causing odor.

 

Seal failure: Poor seals on floor drains and pipe joints allow sewer odors to penetrate plastic components.

 

Solution:

Preferably choose food-grade PP or antibacterial modified plastics to inhibit bacterial growth.

 

Regularly clean cracks in plastic surfaces with a baking soda and white vinegar solution to eliminate mold growth.

 

Install odor-resistant floor drains and reinforce pipe joints with silicone seals to block odor sources.

 

4. Dimensional Deformation

Cause Analysis:

Thermal Expansion and Contraction: Temperature fluctuations cause imbalances in the linear expansion coefficient of plastic parts.

 

Insufficient Mold Precision: Deviations in mold shrinkage calculations during injection molding lead to dimensional instability in the finished product.

 

Solution:

Use CAE simulation analysis to optimize mold design, predict shrinkage, and adjust tolerances.

 

Select low-shrinkage materials (such as PPS and LCP), or add mineral fillers (such as talc) to reduce deformation.

 

5. Surface Scratches and Wear

Cause Analysis:

Insufficient Material Hardness: Low-density PE and PP materials are easily scratched by hard objects.

 

Frequent Friction: For example, the surface coating of a showerhead connector may peel off due to prolonged rotation.

 

Solution:

Use nano-coating technology (such as ceramic-like coating) for surface treatment to improve wear resistance.

 

Avoid sharp contact points when designing the structure, such as by adding rounded transition edges.

 

6. Visible weld lines

Cause analysis:

Uneven injection molding flow: The melt is too cold when it merges in the mold, resulting in visible welds.

 

Solution:

Increase the melt or mold temperature and optimize the gate position to promote full melt integration.

 

Add a flow promoter (such as silicone) to improve material flow.

 

7. Leakage at threaded connections

Cause analysis:

Insufficient thread precision: The tolerance between the injection molded part thread and the metal fitting is too large.

 

Long-term stress relaxation: Plastic creep under sustained pressure leads to seal failure.

 

Solution:

Process threads according to GB/T 7307 standard to ensure Class B precision.

 

Use metal insert injection molding technology to enhance the mechanical strength of the threaded area.

 

8. Poor Chemical Resistance

Cause Analysis:

Improper Material Selection: Ordinary ABS is easily corroded by strong acids, and PVC is not resistant to organic solvents.

 

Solution:

Replace with a highly chemical-resistant material such as CPVC or PVDF.

 

Spray an epoxy coating on the surface to isolate the corrosive media.

 

9. Assembly Difficulty

Cause Analysis:

Dimensional fit issues: Fluctuating shrinkage of the plastic part causes assembly interference with the metal part.

 

Design Flaw: Insufficient strength of the snap-fit ​​structure, resulting in breakage after repeated disassembly.

 

Solution:

Optimize injection molding parameters through orthogonal testing to stabilize shrinkage.

 

Use in-mold assembly technology to reduce post-assembly steps.

 

10. Environmental Compliance Issues

Cause Analysis:

Excessive Hazardous Substances: Recycled materials contain heavy metals or phthalates.

 

Solution:

Strictly comply with RoHS and REACH certifications, using halogen-free flame retardants instead of traditional additives.

 

Establish a closed-loop recycling system to modify and reuse waste materials.

 

Summary

Quality issues in bathroom plastics require a systematic approach encompassing material selection, process optimization, design specifications, and routine maintenance. Manufacturers can leverage technologies like CAE simulation and online monitoring to improve yield rates. Users should also pay attention to product certification and operating environments to avoid overloading. Through collaboration across the entire industry chain, high-durability and environmentally friendly bathroom plastics can be achieved.