Source from : http://www.chineseplywoodsource.com/ my own blog
the foreign importers always compainted that why most of the new chinese plywood exporters or manufacturers’s prices are so low than their current suppliers.they should learn something ,then they can know who are playing games .
normally new sellers sometimes play games on thickness tolearance and testing methods ,if the buyers don’t know or don’t explain how to use and where to use the plywood,maybe some problems will be created .I have met these for everyda .
Tested one crate by one crate and get an average thickness
12mm ,75 pieces per crate ,if we requested is +/-0.5mm,Minimum thickness should be 11.5mm ,Maxmimum thickness should be 12.5mm.Now,one crate total 75 pieces ,
means the whole crate Minimum thickness is 862.5mm ,MAX thickness is 937.5mm.
See the above Picture,we tested one crate thickness 884mm ,means our whole crate thickness can meet Min 862.5mm.
Then 884 divided by 75 is 11.78MM.No matter the single piece is 10mm or 13mm they don’t care .
But you know ,between the plywood there are some GAP ,so ,this is not exact thickness for each plywood.We prefer to
use SINGLE PIECE TESING AS OUR CLIENTS AND CUSTOMERS’S REQUESTED.
Tested the thickness one piece by one piece SINGLE PIECE
Fyi ,test every piece of the 75 pieces ,make sure every single piece ‘s minimum thickness is 11.5mm
Two Different Methods of Thickness Measurement
There are two different methods of thickness measurement in plywood grading rules and inspection skills and methods for exporting markets already used since 2010.
Tools: Calibrator and Steel Tape
Two different Methods:
- Calibrator Tools Measurement: Inspect one piece by one piece. Check every piece of plywood thickness.
- Steel Tape Measurement: Inspect one crate by one crate (one Unit or one Pallet), one crate will be taken as a whole.
Calibrator Tools Measurement, we also called individual measurement .means accurately and precisely thickness measurement, accurate measurements and checking. Their measurements are correct to a hair’s breadth. These methods are always called inspected one piece by one piece. This method does not have realistic meaning if regular traditional common plywood quality, because the quantity and task is very huge .Normally randomly checking 2 to 5 crates of plywood from one container by this method, if can meet the thickness tolerance requirement, means the whole production can meet the quality requirement. This method is always used for the following situation:
1) New Supplier
2) Old supplier but don’t have good reputation and have repeat quality claims or problems
3) Special thickness requirement like platform or Lamination Grade plywood …
4) Quantity is less and don’t have repeat Purchase
For Example : Black Film Faced ,1220x2440x18mm,Thickness Tolerance +/-0.5mm ,50Pcs/Crate ,18 Crates/40’HQ ,900Pcs/40’HQ .Regular quality standard .Accept 5% to 8% thickness tolerance exceed +/-0.5mm but less than +/-0.7mm .
The inspector will randomly select 2 to 5 crates from the whole production without prior notice.
Let’s assuming that the inspector randomly selected 3 crates from the whole production ,total 150 Pieces .The used the first method to check the thickness ,found 125 pieces can meet the quality requirement +/-0.5mm ,another 15 pieces are in +/-0.7mm thickness tolerance ,another 10 pieces more than +/-0.7mm .Let’s calculate that the product percent of pass is 93.3% ,means the percent of pass more than 92% ,this is good production can meet the agreed thickness .
Steel Tape Measurement, also called WHOLELY measurement, one crate is taken as a WHOL or Unit, means roughly measurement, not accurate or precise measurement, it is not individual measurement. The required precision is loose for single and individual piece thickness tolerance. This method is always used the following situation:
- Old suppliers who have good reputation and organized production process.
- Regular and Standard or common Quality requirement for the thickness, nobody know what these plywood are used for, suitable for giant importers and wholesalers and distributors.
- Huge Quantity Purchase orders are shipped in short time and no special quality requirement.
For Example : Black Film Faced ,1220x2440x18mm,Thickness Tolerance +/-0.5mm ,50Pcs/Crate ,18 Crates/40’HQ ,900Pcs/40’HQ .Regular quality standard .Whole crate thickness are from (17.5mmx50 ) 875mm to 925mm (18.5mmx50) .Individual thickness can not be less than 16.8mm .
Let’s assuming that the inspector check every crate by his inspection tool Steel Tape ,measure the whole crate ( 50 pieces as a whole ) thickness is 900mm ,means the whole crate thickness can meet the quality requirement .
If the whole crate thickness measured less than 875mm or thicker than 925mm, means the whole crate will be rejected can not be shipped out of China.
Different Customers or MARKETS have different quality requirement at different times for different purchase orders .Normally these two methods are mixed used by most of the inspection inspectors and Inspection Rules. If you don’t often travel to China, it is very difficult for you to know the second method was already used for many years by many importers.
If some special request, we MUST state the inspection method in the purchase order in order to avoid any mistakes or quality claims.
If any questions please kindly let me know.