What to do when there are bubbles or depressions on the surface of WPC decking
There are many reasons which may cause bubbles or depressions on the surface of WPC decking, Sure engineer suggest the operators check below reasons and solutions to solve the product:
Fault manifestation:
bubbles, depressions and other defects appear on the surface of the extruded wood plastic floor, affecting the appearance and quality of the product.
Bubbles and depressions on the surface of wood-plastic flooring may be caused by problems in the production process, raw materials, or use and maintenance. The following are specific reasons and solutions:
I. Analysis of bubble problems
1. Production process defects
Uneven mixing of raw materials:
Wood-plastic materials are mixed with wood powder, plastic particles, additives, etc. If the mixing is not sufficient, the local plastic will not melt completely or the gas will not be discharged, and bubbles will easily form after solidification.
Improper processing temperature control:
The temperature is too high during extrusion molding, and the plastic will overheat and decompose to produce gas; if the temperature is too low, the plasticization is not sufficient, and the internal air cannot escape, which may cause surface bubbles.
Insufficient pressure:
The pressure is not enough during extrusion or pressing, and the material cannot be compacted. The gas is trapped inside and bubbles are formed after cooling.
2. Raw material problems
The moisture content of wood powder is too high:
The wood powder is not fully dried and contains water. The water evaporates at high temperature to produce water vapor and form bubbles.
Too many volatiles in plastic particles or additives:
Recycled materials or inferior plastics contain more volatile impurities, which release gas when heated.
3. Impact of the use environment
High temperature exposure:
Long-term exposure to sunlight will cause the surface temperature of the floor to be too high, and the small amount of volatiles remaining inside will expand, which may cause bubbles.
Improper installation:
The ground is uneven or the spacing between the keels is too large, the floor is unevenly stressed, and local extrusion causes internal gas to overflow and form bubbles.
II. Analysis of the dent problem
1. Production process defects
Insufficient cooling and shaping:
After extrusion molding, the cooling speed is too fast or the cooling is uneven, the surface solidifies quickly and the interior is not completely shaped, resulting in shrinkage and dents.
Mold wear or design defects:
The mold surface is not smooth or the flow channel design is unreasonable, the material flow is blocked, and the local filling is insufficient, forming a dent.
2. Raw material problems
Imbalanced ratio of wood powder and plastic:
The wood powder content is too high (exceeding the formula standard), the material rigidity is insufficient, and it is easy to cause dents due to shrinkage or external force; if the plastic ratio is too high, the flexibility is poor and it is easy to dent after impact.
Uneven dispersion of fillers:
Fillers such as calcium carbonate agglomerate, the strength of local areas is low, and dents appear after force.
3. Improper use and maintenance
Heavy object squeezing:
Putting heavy objects such as furniture and equipment for a long time exceeds the floor's bearing capacity, causing the surface to dent.
Sharp object scratches:
Sharp objects such as metal utensils and high heels scratch the floor, causing local dents or scratches.
Too small installation gap:
The floor has insufficient expansion joints, and they squeeze each other during thermal expansion and contraction, causing the edges or surfaces to dent.
III. Solution suggestions
1. Improvement on the production side
Optimize raw material control:
Ensure that the moisture content of wood powder is less than 8%, and dry it before use;
Select high-quality plastic particles (such as new PE/PP) to reduce the proportion of recycled materials;
Strictly mix the raw materials according to the formula, stir them thoroughly, and add defoaming agent to reduce gas generation.
Adjust processing parameters:
Precisely control the extrusion temperature (such as PE-based wood plastic temperature is about 160-190℃), and increase the temperature in stages to avoid overheating;
Increase the extrusion pressure (such as 10-15MPa), extend the holding time, and ensure that the gas is fully discharged;
Optimize the mold design, regularly maintain the mold surface smoothness, and avoid uneven filling caused by wear.
Enhance cooling and shaping:
Use progressive cooling process to avoid uneven internal and external stress caused by sudden cooling.
