Blockboard QC Inspection Checklist : Part 4 Signing Standard for Grade Quality of Blockboard
The quality of blockboard can be checked according to the national standard of blockboard. The quality of Kanban can be judged from three aspects: dimension tolerance, appearance quality and physical and mechanical properties.
1. Dimensional tolerances: There are two types of thickness and dimension tolerances, such as surface non-sanding, tolerance value is (+0.8-+1.0 mm), surface sanding, tolerance value is (+0.6-+0.8 mm). The allowable tolerance of length and width is + 5 mm, no negative tolerance is allowed, warpage is allowed to be in the range of 0.2-0.3 mm, and waviness is allowed to be in the range of 0.3-0.5 mm.
2. Material and processing defects: according to international regulations, they are classified into three grades: first, second and third. In order to ensure the dimensional stability and stress uniformity of the board in use, the veneer with symmetrical layers on both sides of the core board should have the same thickness, the same or similar species, and the texture direction of the two-layer middle board with the core board adhesive should be the same, and be perpendicular to the texture direction of the core board. This is the first condition to observe the quality of boards, in addition to visual inspection of material defects and processing defects of blockboard. Insufficient knots, dead knots, skin clips and patches in watches and backplanes. Processing defects such as seam jointing, rolling, burr grooves, penetration contamination, panel lamination, etc. decrease with the increase of defects within the scope permitted by the national standard. But Blockboard of any grade is not allowed to open glue and bubbles. It is also stipulated that no impurities, adhesive tape or obvious paper marks shall be left on the board.
3. Physical and mechanical properties: This index can only be checked by experimental instruments, including moisture content, transverse static strength, shear strength of rubber layer, etc. Its quality can only be divided into two grades: qualified and unqualified.