Chinese Plywood

      Cabinetmakers complain about the quality of hardwood plywood imported from China. April 13, 2012

Question
I am cutting a lot of 5/8 Chinese plywood. It has melamine laid up on both sides. I am in NC where we have been having average mid to low 90s and high humidity. This stuff starts to curl up as soon as you break the band. I usually cut melamine with particleboard core, so I am new to plywood. I have a Becker vtlf-250 pump, but the curl is too much for it. Is it the Chinese plywood or just the heat and humidity? Or do I need to look at a stronger pump? Cutting on Biesse Rover 30.

Forum Responses
(CNC Forum)
From contributor J:
I would think that the plywood is the problem. I cut a lot of the 3/4 Chinese birch with UV finish on 1 side and 2 side. Some is real crap and will not suck down. I have the same Becker pump but have 2 of them. I mostly use 1 pump, but on a warped sheet, or if the spoilboard has been cut on a lot, I use 2. The supplier I get the Chinese birch from has been giving us some pretty good stuff. Other suppliers have crap and there does seem to be a difference even though the supplier who has crap says it is all the same and everybody gets it from the same place. I had just about given up on the stuff until I got some from this other supplier. If the stuff is curling after you cut the bands, you've got problems and it will probably not suck down even with 2 pumps. The Chinese ply is a crapshoot.



From contributor S:
I replaced a whole job made from Chinese chicken skin plywood. Junk! The alder veneer had more bubble than the cheese on a pizza. And the plywood splits during machining.


From contributor K:
Be careful of pieces of metal in that plywood. I ruined a sawblade cutting Chinese plywood and now use a metal detector before I put a piece on my CNC.


From contributor B:
Can I ask why you are all using the Chinese plywood? Is it less expensive and usually okay? Or is it all your suppliers are carrying now? Some other reason?


From the original questioner:
The customer is supplying the material. Kind of having a hard time getting a production line smoothed out, having to turn over 30% of the sheets and having 10% that I can't cut at all.


From contributor C:
If you can get it flat, just wait till you start cutting it. They have figured out that glue is cheaper than wood and it has a lot in it. It is terrible on tooling. I get calls on this 2-3 times a week and it usually starts out with my tooling is not lasting. We do have some harder grades of carbide that we are having a little better life with.


From contributor H:
We got a lift in for structural parts. Sent it back due to everything!


From contributor M:
I decided to try some Chinese ply when I built shop cabinets just to see if it was usable. The veneer would splinter no matter what, and peel off in dinner plate sized sections on about 15% of the parts. The edges simply would not take a screw without splitting. I don't think I cut a single panel that didn't warp. Most of the sheets had some kind of staining due to mold in spots.

I could never sell something like that to a customer. Not even for paint grade work. Due to the fact it would delaminate randomly and would barely hold a screw, I wouldn't even use it for an applied base that would never be seen.

I certainly hope there are better products out there from Chinese suppliers. I haven't come across any yet. I also bought some 1/2" plywood in a pinch from Home Depot. I don't think it was Chinese, but I am not sure of the origin. One of the sheets warped to the point where it was unusable before I got it back to my shop. The veneer was so thin you could not sand it at all without sanding through. I should have known better when I saw that they had almost sanded through in spots from the factory. Ended up being a complete waste. I don't even know why they sell stuff you can't even use. I suspect a lot of reject material makes it onto store shelves and into the inventories of suppliers when it should have been sent to the landfill to begin with.



From contributor T:
The metal you find in between the layers are the snap off type razor blades they must use in production. Nice, huh?


From contributor P:
You could move up in size to a 500 series pump from Becker for a scant $17K minus the cost of your existing one, if you can manage to sell it. Frankly, I'd be more concerned about work pieces coming loose when you're trying to machine stuff. Routers can be pretty expensive to fix.


From contributor R:
For an economy 1/2" stock ply with the least warp and one good face, what would you recommend?


From contributor A:
To the original questioner: seriously, I understand the general consensus that some Chinese product is real crap, but to be productive, what is the application? MDF and flake cores are flat and less expensive. Plywood is available flat, but if the cost of Columbia or another good quality board doesn't work for you, what is it you are trying to accomplish? Is OSB a viable option?

A rapid change in humidity may affect the first sheet or two in a lift, but after that there is little moisture imbalance between the faces of a given sheet. Warp is caused by unequal stresses and that is indeed often built into the board at the time of mis-manufacture.

Thermwood and others make a pressure roller system that rides along with the spindle and gantry to deal with situations like this, and for stack cutting too. I do not know if Biesse offers such an option for the Rover.

If your volume is low you may be able to utilize an edge clamping system either separately from or in conjunction with your vacuum. Some inexpensive routers use edge clamps instead of vacuum. It can be as simple as a piece of aluminum angle or bar stock attached to a set of toggle clamps or as sophisticated as a pneumatic actuated bar or rod engaged with G code level commands.

I sometimes need to nest my parts avoiding the corners of a sheet. I can then place a 1-inch screw for 1/2 inch material or a 1-1/4 for 3/4 material in the corners manually and help hold down a sheet. It helps a lot to place the sheet concave side down if possible. This does not help much with saddle shaped sheets though.



From the original questioner:
It's not my choice. I'm just cutting the customer's material. He needs to use plywood for his application. I am going to try to convince him to switch to American made board.

I just needed to know if this was normal, as the material supplier is saying I don't have a large enough vacuum. Being new to plywood I did not know it was my vacuum, the humidity, or the board. I can usually get most of the boards to suck down by flipping them over. But some is wood grain on one side and white on the other. So flipping them over is not an option.

I can add another vtlf 250 if I really need, but I don't think it will do any good.



From contributor A:
One thing for sure (and I have heard this line from material suppliers before), your plywood supplier is full of *&%$&. No amount of vacuum is going to pull down the corners of a sheet that are more than mildly warped.

Your pump is a 10 HP rotary vane. Excellent quality unit, perfectly capable of holding work. You have not got a lot of extra pumping power, so you can't waste it. Covering unused areas of the table or zoning the table and sealing the edges of the spoilboard are important, but I ran a similar unit for many years on a 5 by 10 table and was fine with it, and hundreds of other people do every day.

I agree, switch to a better board. You may find the cost to be not too different in the end, and the savings in time and waste will likely make the better product cheaper.



From contributor Y:
Chinese plywoods are tough to get straight on. That is the core of what I use everyday. I run a Weeke router at my shop but have the same Becker pump you do and I do not have the issues you are talking about. That comes largely from the fact that I have been through the ringer on this long enough to know that there are different grades of the import material no matter what one salesman may or may not say. They want to sell the stuff they buy for the cheapest because it makes them more money.

The stuff we bring in now is referred to by the two companies that supply it as "calibrated core." Which basically means it has a nicer core than the bottom end stuff. There are way less voids than the cheap stuff, the veneers peel much less, and the cores have fewer plies than the really low end material. I have some salesmen who say their material is the same and we usually have them pick it right back up after we cut the banding.

Also, the price is about 2-3 dollars per sheet more than the low grade stuff, so still much cheaper than domestic. I would change over to domestic but I have yet to find that customers want to pay the extra money for that, no matter what the job size is. We typically work in million dollar homes and even they want the cheaper options these days.

You should tell your customer to let you purchase the material for him so you can get your hands on it and make the right decision. Don't be afraid to ask for 2 or 3 test sheets to cut up before you buy a unit. We do it all the time now when someone is promising us the moon. Not one supplier has declined to send the sample sheets for free yet.

One last thing... Though I use import core material for my boxes, I do not use it for exposed ends, cases, or anything that is on the outside of the cabinetry. That is either domestic or MDF core material. The inconsistency in the cores shows through finish and makes for a service nightmare!



From contributor Z:
We have had nothing but bad experiences with Chinese plywood as well. We purchased a C-2 grade for the fixtures we build. Not only is warping an issue regardless of the climate, but edge fuzzing is a problem regardless of how sharp the bit is. We used a Vortex 3252C router bit, which helped with the edge fuzzing, but the life of the bit would reduce significantly with this type of plywood. We have now switched over to Selex ACX which is an A/C grade plywood out of South America. The same price point, but warping has been minimized unless the weather is really hot and humid. Edge fuzzing has nearly disappeared regardless of how dull the bit becomes. It's definitely worth trying out if cost is an issue.

I too would buy a domestic plywood if the price were right, but haven't had any luck finding anything economical. If anyone knows of a low cost domestic plywood, let me know.



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