Timber grading

Hi, I know there are a lot of people on this site with experience in the timber industry, so I wish to draw on your knowledge. I am presently working in a timber mill where the timber is visually graded by the operators who place a chalk mark (different symbol for different grades) on the timber to indicate the grade and dock required. The timber then goes through a lucydyne scanner which reads the mark and returns a combination of digital inputs to the PLC. The operators are very slack with the quality of their marks (due to the timber moving past) which means there are a lot of misgrades. I am wondering how other plants do this process, ie has anyone tried a mark in different areas of the board to indicate grade.
That is put 4 divisions on the board with laser beams (3 laser beams 4" apart) and a chalk mark anywhere in that area of any pattern to indicate the grade.
I await any ideas or suggestions. Regards Alan Case

I have zero experience in the timber industry beyond the lumber aisle of Home Depot, but anyway...

How about marking the timber with a UV marking pen, then reading the marks with a UV sensor?...

The links I provided are just examples I found in a quick Google search.

beerchug

-Eric

Could they put stickers with barcodes instead of chalk marks?
Maybe Color code the Stickers???

BTW I have as much experience in the Lumber industry as Eric.

Sometimes ideas out of left field help lead us to a better solution.

How about a system with a few push buttons. The operator would press a button corresponding to the grade chosen. Each button would activate a bar code printer which would print the appropriate code on the piece. Then the bar code reader could read the code.

I did something similar a few years ago with tires.

Several factors were invloved.

The weight of the tire would automatically send it down a chute.

It would be balanced and maybe sent down a chute.

Physical inspecion could divert it.

When it was all done, there was a rack of perfect tires, and depending on the number of marks imprinted along the way by "dot placers" and the location of the mark placement, determined were the rest of the tires went, and which store got what was supposed to be identical "good" tires. Most marks were read with a photoeye looking for a "light" indication.

You could possibly use paint. I worked on a plant where they finger joint timber to make long lengths. At each end of the timber a blue mark was sprayed which a Sick colour sensor picked up on. When the sensor saw the mark the timber was clamped and pressed together.

Maybe you could have a grading station where the operator could grade the timber and select the colour to spray for the grade via push buttons. The spray duration could be controlled by a timer.

You have one of the best systems available.

However, I don't agree with the basic idea that marking lumber is any better than pushing buttons. Writing is much harder to do that pushing buttons. I don't know of any scanning system that can grade as well as a person and that is the problem. Even back in the 80s when I was doing lumber sorters we had a high a low grading line so that there were two people grading lumber instead of one. I think having two separate lines was a little costly but it didn't take much space as one as above the other. Another idea would be to have multiple trimmer/grader people grading every 3 or 4th board. A colored light would be required to indicate which board a particular grader should grade. This would reduce the load by the number of graders. However the labor costs go up.

I tried grading lumber for just a few minutes in the 80s. You guys can believe how mind numbing it is grading a board every second or faster. It is not easy because it requires total attention. Try it and see.

There are no simple answers. The ultimate answer would be to get one machine that can do the grading without human assistance but that may be a few years out yet. I would keep in touch with the leader in scanning technololgy in the industry. The Lucidyne guys are pretty sharp and are always push technology.

BTW. I worked with most of the senior guys now at Lucidyne in the 80s before Lucidyne was started. Its a small world. I wonder if any of our hydraulic motion controller are in your mill.

Thanks to all. They use 5 graders at present and each grader marks approx every fifth board. As there are 90 boards going past every minute then there is no time to place stickers etc. I might do a bit of research into the Lucydyne products as I think the have a lower end model. Colour not recognised.

Peter, what brand are your controllers? I will check what there is here. The whole mill will be demolished in 4 months time as the new mill comes on line so if they are on site I will have to be quick. After Christmas when they reach full production they will be the largest in the southern hemisphere and fifth largest in the world (so they tell me)

What system of marking did you find worked the best. They are trying to put a 6 on the timber here as a grade mark and it is not too successful.

Regards Alan Case

This may be a little bizarre but bear with me, it's past my bedtime.

IF the boards could be fixed in place on the conveyor: an overhead camera scans the marking area. Each inspector 'marks' the bad sections with a laser or other light source which the camera can detect. When the camera 'sees' an illuminated defect area, it can synchronize that spot with the conveyor movement and something downstream can apply a definite, consistent paint mark for the cutter. Think along the lines of 'painting' a target for a laser guided bomb.

I believe that grading occurs downstream of trim saws and only determines where the lumber should be stacked when taken off the "green chain". My experience pre-dates automatic green chains. When I was a "puller" on the green chain, we read the mark ( a crayon 'B', 'E', 'S', 'C', etc.) and stacked in separate piles according to mark and length. The graders have to inspect both sides of a board, but occasionally miss. More than once we would pull a seemingly good board only to find the underside full of teredoes - yuk! Then you'd have to handle it again to throw it back on the chain so it could go to the reman pile.
Do you get teredoes in Oz?

hi

We use a newnes grademark reader (they brought Luncidyne out)
apparently they have improved the grademark readers quite a lot and they seem to be very flexible with the reading of the grade marks.

Im quite impressed with ours.

Are you sure its not a light level problem with the uv tubes or
the back bar reference strip is worn/dirty?

this can have a big effect on the grade mark interpretation.


Our old mill had a combination of pe cells and push buttosn to determine the visual grade.

the stress grade was colour blazed on the board and detected on the lug chain just after the trim saws with a colour sensor whic in turn operated our inkjet printers.

hope that helps

Hi, the grading is done before the trim saws as part of the grading mark is what dock is required. The grading is the only time that the boards are touched as everything else is fully automatic (except for misgraded boards having to be pulled out at the stacker)
What is a teredo? Regards

member

Hi, I work for Lucidyne Technologies, Inc. and have for about 15 years.

The technology today does include systems that can grade lumber for both geometric and biological defects. The cost of these systems can be quite expensive.

In response to one reply, Lucidyne has not been purchased by Newnes. The purchased the Peter Appleton system.

The manual marking with any system is going to only as good as the people doing the lumber marking.So, it is very important to use markes they are easy to make and will not be confused with other marks that can lead to misgraded lumber. Take time to review these marks and impress upon the graders how important their job is. I have seen many mills that run with less the 1/2% rejects.

Hi Alan,

Actually I built an entire optimising cutoff saw using and SLC5/03 and IMC110 about 10 years ago, using just such a chalk and UV sensor arrangement. I agree with you, it is totally dependent on the quality of the grading operators marking to make it work.

Luci

The graders are very important and yes it is a numbing mindless job. You become a robot thinking only about a long list of critera for each board. My wrist hurt after 2 hours. ( you have to turn each board). I use to watch when rejects started getting high. Many times the problem was the flash tubes, not the grader. Even if they are working, they might not be as bright and may need replacing. Luci is a high maintenance tool. Also ambient light getting inside the camera area can wash the image. If you watch the monitor you may see the odd faded image. Working right, everything in good shape, graders keeping alert, you should be over 97%. Lucidyne is one of the better grade readers. I am now off work and going to enjoy a long weekend.... Have a great weekend!
Bruce.