Plywood QC Inspection Checklist : Part 12 things you may not know about CORE structure Types and Quality,
When inspect the plywood ,accordingto the buyers’s request ,normally should check the core structure types first ,because the Plywood core structure type plays an important role in the final applications of the plywood .
But this is not a simple work to distinguish the inside plywood core structure . Sometimes, due to the closure or treatment of the plywood edge , it is difficult to distinguish the inner core structure from the edge of the plywood. This requires the QC to use their professional experience and skills to distinguish.
Now, according to some of my personal quality inspection and production experience, do some simple introduction, hoping to provide some help to buyers or consumers.
1.Traditional Fresh veneer core structure
Why I use the two words of Traditional ,and Fresh ?
First ,traditional means always from the beginning of the plywood industry manufacturing ,always use veneer .Why I used the fresh here ,because fresh veneer is from the logs directly ,actually the fresh veneer is like virgin or Male virgin, the first time used for plywood manufacturing .
7 years ago ,when I inspected some film faced plywood in linyi ,I have one principle that before any finished plywood inspection ,I must check their whole production line .So I requested the factory’s boss to show me their production line and how they made the plywood .But the boss refused to show me and explained too much that their platform were produced in their new factory ,and the factory is very far away from the hot pressing factory .So I gave up then .
But when I inspected the plywood,I always try to check the long span loading capacity of the plywood ,I found the structure of the film faced plywood was notgood ,then requested the factory to cut the whole piece and show me why .After they cut the plywood,I found the plywood core I HAVE never seen such core ,like lumber blockboard core .Finally they explained to me this is a new type of plywood core to make plywood,they called it The second generation core plywood ,now we called them recycled joint core blockboard .
FYI :Tilt the plywood 45 degrees, then stand on the board and jump to test whether the structure of the board is reasonable, load-bearing performance and so on. If it is a plywood of furniture grade, a person of 50 to 60 kilograms usually jumps on the board for a few times. If there is no clicking sound coming from the inside of the board, the structure of the board can be simply judged to be very good. If there is a click sound inside the board, it indicates that the structure of the board or the materials used are not qualified. If it’s a film faced plywood or construction grade plywood, it takes 60 to 80 kilograms of people to jump on the board, usually tilting the board 40 degrees.
2.Recycled joint core
The recycled joint core ,also called The second generation core ,like prostitute or Dancing male ,used many times .These second generation core are recycled from the construction sites or other applications .Cut these recycled plywood to long strips or small piece of blocks ,then glued together to make the platform for low quality film faced plywood production .
The quality is low ,but cheapest core .
Now ,we even saw some manufacturers using this kind of recycled core to make furniture for exporting ,even for domestic , It’s a retrogression of history. Because of the loading capacity is weak ,formaldehyde emission rate is too high .It is very dangerous .
But one most important factory affect the final plywood quality ,the recycled core film faced plywood have a very good and better improved surface ,flat and smoothness .just like two times hot pressing ,or sometimes three times hot pressing film faced plywood .
Advantage : Flat and smoothness
Disadvantage : weak ,and high formaldehyde emission