Polywood Quality Control Inspection Case Study


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The common problems and defects which could be found in plywood manufacturing.The defects emerge either in the core or on the surfaces. The main defects -gluing defects, structure defects, and appearance defects. One customer purchased 3450 pieces from one new supplier located in Linyi City Shangdong Province. For the first time cooperation with the supplier, they worried about whether the quality can meet the specification and quality standard so they decided to go through a final random inspection with the Verquality QC team.

The shipment quantity of Polywood was 3450 pieces and our team picked up 125 pieces of product samples for inspection. The major defects were 39 pieces and the minor defects were 16 pieces

1. Gluing defects

1.1 weak bonding 

The bonding strength of polywood is lower than the standard value and main reason is the quality of adhesive is not good quality and the hot pressing process are not well controlled such as low hot pressing tempreture, insufficient pressue setting or short time for the pressing. Also may cause by low veneer moisture content, insufficient glue distribution and poor veneer quality.

1.2 Delamination or bubbling

If the failure of the slab is entirely in the glue layer, it ban be regarded as glue opening. The reason for this kinds of defects are that pressure drop is too fast and hot pressing time is insufficient, the moisture content of veneer is too high or the amount of glue applied is too large, there are blank spots or inclusion on the veneer during glue application, sticking stains.

2. Structure Defects

2.1 Warping 

For some cases, the polywood warps and deforms. If the board is placed horizontally, the degree of warping can be observed. The reason is that the moisture content of surface and backboard is inconsistency, the veneer of different tree species is not matched. The veneer has torsion patterns, and temperature of individual hot press is not enough and the stacking place is uneven.

2.2 Too high moisture content 

The moisture content of the board should be higher than 12%. Any polywood that exceeds this limit should be taken out from the shipment.

3. Appearance Defects

The below defects were found during the inspection. General speaking, the quality of this shipment was very bad.

Chipped edge


Broken Corner

Rottern of core

Face veneer delamination