Nelson Bros Engineering Scanner / Optimizers
Board Edger Description
www.millsmart.com/edger.html - (360)951-2737 - Updated 5-Dec-2010
NBE has installed over 70 Board Edger
Optimizers. Prior to starting NBE, Rod Nelson developed optimization
programs for several "Big Vendors". He is a "self
proclaimed" expert on optimization, though many people believe his brother
is the real brains in the outfit and that Rod is just another "pretty face".
There are two basic methods of scanning boards. One is the Transverse Scanner where the board travels laterally thru a scanner that spans the length and thickness of the board. Two is the Lineal Scanner, where the board travels lineally thru a scanner that spans the width and thickness of the board.
Transverse scanners can be differential (top and bottom) or top only. Boards are normally conveyed thru the transverse scanner on a lugged chain or between hook stops on a slick chain. Our earlier systems used scan heads with multiple single points lasers on 3” or 1” centers. Some other early configurations of the multipoint scanners included a thru beam light-curtain with beams every 1/4" or 1/2" to improve width and length resolution.
Since 2005 we have switched to line laser profiling heads like the JoeScan JS-20 head. Surround scan configurations consist of 3 banks of heads that get data side data as well as top and bottom. A staggered, surround system gets real data on the ends if length accuracy of +/-0.1” is needed. For some edger application we can us 1 or 2 banks of heads that scan from the top.
Lineal scanners are normally top only or top and sides. Boards are normally conveyed thru the lineal scanner on a belt or feedchain. Differential scanning (i.e. top / bottom) is possible, but requires a break in the scan belt to get access to the bottom of the board. The most simple lineal scanners has a single scan zone with a line laser profiling head on each side. The length of runway from the lumber line thru the scan zone to the edger can be a problem for some mills. The most simple lineal scanner consisting of a rollcase feeding a belt conveyor thru one scan zone requires a runway of 2 to 3 board lengths. A shorter runway is possible if a centering infeed table is used with multiple scan zones. Kockums and Ahlstrom introduced the multizone scanner with centering infeed in the late 80's, McGehee (with NBE’s help) rekindled the lineal system in 1997. Now most vendors are switching to the lineal system.
NBE has installed over 40 lineal scanners on new new edgers and upgrades to the earlier lineal systems. We currently use the JS-20 scan head from JoeScan on lineal edgers as well as log and curved cant systems.
Customers are continually saying that the
lineal system just won't fit. My answer is that the price of a building
add-on and some conveyors is cheaper than a Positioning Table and a Transverse
Scanner. Ask your maintenance people if they would rather maintain a roof
or a Positioning Table!!!!!!!
NBE's Opinion is that simplicity and accuracy is most important. Therefore the single zone lineal is best, then the multizone lineal, and lastly the transverse with positioning table. NBE wrote an article for the July/August, 2001 issue of the Timber Processing magazine explaining the benefits of lineal scanning (refer to link at end of this webpage).
Things to consider when selecting the scanner:
NBE has the best Optimization. OK, I may be biased, so you should not take me on my word.
So how do you select one. When I was a young electrical engineer, people would ask me what TV to buy. My answer was to list your requirements, read the specifications on all of the candidate TV's, write up an assessment chart, make the wrong decision and live with it. No one ever asked my advice after that.
So how do you really select a scanner / optimizer. Well you need to address the following:
1. Does it do what I want?
2. Can it be maintained?
3. Does it have the best Return on Investment?
4. Am I getting an exact copy
1. Does it do what I want? To keep from having to write a book, I will list the most important capabilities of the NBE edger optimizer:
Like any vendor, we can do anything, but you should know what exists and what is new. Then, keep in mind that new tends to be a bad word.
block diagram is for a lineal board edger. The optimizer computer is
networked to the scan heads and to the supervisor's switching hub. The
switching hub allows multiple monitor computers to display the optimizer
solutions or get reports without any burden on the optimizer's network.
Single Zone Lineal Board Scanner.
Click image for large picture.
important display is the following solution screen. It gives a graphical
display of the solution in real-time, a profile plot, a list of the last 100
boards, plus some production and decision text. This screen is
displayed on the optimizer, supervisor and any monitor computers. The
optimizer's monitor is normally positioned within the operator's view.
NBE's Supervisor's Solution Screen
NBE's solution screen for the RANDOM WIDTH edger optimizer.
Now we are ready for the second major requirement
2. Can it be maintained? Anything can be maintained, the question should be, "what is the cost of maintenance?" The ideal system never fails, never needs to be calibrated and is so simple you never need to call the vendor for help. Sadly, even NBE's system is not ideal.
To determine the cost of maintenance, you need to address the following questions:
Obviously, you need a Crystal Ball to answer the 5 year questions. But, do not assume the bigger vendor is always more safe. The big vendors disappear or get acquired (code word for no longer supported) as often as small vendors.
NBE approach is to keep it simple and do not hide obvious charges:
So once you believe it meets your needs and that is will still be running in 5 years, it is time to look at the ROI.
3. Does it have the best Return on Investment? There are many approaches for assessing the economics. Whatever assessment you use, you will need to define the following:
When mills buy a system they tend to focus on production (pieces per minute), recovery (98% to 99% of something), system cost (not total cost) and the installation schedule (can you deliver in 6 weeks). Since vendors all promise the same thing, mills usually rely on cost and confidence to make the selection.
During installation people usually wish they spent more time scheduling, selecting the startup people and buying the spare parts.
Shortly after installation people wish they did more training and had a better understanding of the warranty. They usually are wondering if the promised piece rate was an exaggeration.
Eight months after installation, people who relied on "gut feel" are wishing they spent more time on their resume.
I could continue, but this type of humor does not sell many systems.
The best advice I can give is "if the vendor can't show you a system doing exactly what you want, then you should always question their ability to do what you want".
If you ask for something, beyond the current state of the art, be prepared. On any new technology, always have a full factory acceptance test. Do not accept shipment until all requirements are met.
Always specify the startup people. See NBE Startups
Define your recovery test or understand the vendor's test. Things to watch for:
Conclusion, Buy NBE.
LINKS TO ADDITIONAL INFORMATION