Kinghorn Systems Engineering
Phone: (250) 426-2158 Fax: (250) 426-2039
Recovery & Yield Studies
Whether you want to know:
- The recovery or yield performance of your present mill
- How your mill will perform with new equipment, or
- What recoveries and yields to use to drive an enterprise optimization (linear programming) model of several mills,
Kinghorn Systems Engineering can help you.
Our recovery and yield studies include:
- Log bucking optimization
- Canter optimization
- Using different equipment (for capital budgeting)
- With different product lines
- MSR (Machine Stress Rated) lumber yields
- Lamination stock yields
Log Bucking Optimization
Bucking optimization studies answer the following questions:
- How good are your bucking decisions?
- What are the bottom line benefits of installing bucking optimization?
- How quickly can you return your investment in true-shape scanning versus X-Y scanning?
- What is the appropriate log bucking data for Enterprise Optimizer models of your sawmills?
Kinghorn Systems Engineering uses our portable tree length log scanner to collect true-shape data on a representative sample (200 to 400) of your delivered logs at your site. Our scanner will work on either kiln tracks or railway tracks, giving accurate results by removing the effects of dips in the rails. You then run the logs through your mill. We record how your mill bucks the logs and what lumber is recovered so that we can establish a base case that we use to to tune our optimized log bucking simulator. We run computer simulations with your cost and sales data, compare the results to the base case and then weight the results to calculate annual returns.
We usually do several simulations with different mill equipment or cutting for different markets as is done with the canter optimization below.
Kinghorn Systems Engineering's true shape scanning of a tree length log on kiln tracks. Logs are loaded onto the yokes with a butt & top grapple loader or with a self-loading truck grapple and scanned one at a time. Typical scanning of up to 400 logs takes a couple of days. Note that we take bark thickness measurements and deduct that from the log diameter in the true shape log images that are captured for computer simulation.
Canter optimization studies are frequently done with tree-length data that is gathered as with bucking optimization but may instead be done by mounting our true-shape scanners on your breakdown line.
Some of the questions answered by these studies are:
- What is the recovery uplift, value uplift and length tally improvement from adding a curve sawing gang?
- How does adding true-shape scanning change the product profile when compared to X-Y scanning and what is the value uplift to justify the change?
- What is it worth to add auto-rotation?
- How does the product profile change by adding sideboard capability to your canter?
- Which products provide the best return for which logs?
- What is the appropriate log bucking data for Enterprise Optimizer models of your sawmills, i.e. If you are running enterprise optimization model(s) for your mill(s), what is each mill's data on product yields for each type of logs?
Canter optimization studies involve mounting our rotary encoder to a sprocket of one of your infeed chain conveyors and installing a light steel frame to mount our four Hermary Opto Electronics LPS-2016 true-shape laser scanner heads on the conveyor, then cutting a narrow, one-inch wide slot in the top part of the conveyor. Since the scanner heads are co-planer (i.e. the lasers and the camera systems all read the true shape of the log in a plane that is perpendicular to the axis of the conveyor), the slot needn't be more than 1" wide. Chain flights will slide across the slot without causing hang-ups. The MPM server software automatically removes the chain flights from the data so that all that remains is a true shape of each log.
Computer simulations are performed as with optimized bucking studies where we do a base case to calibrate the optimization software using the actual lumber yields measured from the running of the scanned logs through your mill equipment and your cost and sales data.
Typical results of the simulations look like:
The graphics on the left show how lumber has been fit into the true-shape log. This is a 7.5" diameter log with sweep and many surface defects. The summary results are shown in the upper right. The potential results of log rotation are shown in the lower left. Note that the selected rotation is at 110 degrees which has a value return of $12.34 is less than the $13.05 at 150 degrees, but the 150 degree result is very localized so is sensitive to the accuracy of the log turner. If the log turner misses by only 10 degrees, the $13.05 result is not achieved. Note also that the yield can fall to $0.00 if the log is rotated 110 degrees in the opposite direction.
For this log, rotation is also very important given the sweep of the log. Recovery is high due to the curve sawing (evident in the center cant) and fitting of sideboards.
This log illustrates curve sawing and critical log rotation.
MSR (Machine Stress Rated) Lumber Yield Studies
The feasibility of installing MSR equipment in any mill is heavily dependent on what MSR grade yields are achievable from your fibre supply.
Kinghorn Systems Engineering will non-destructively test the long span modulus of elasticity (E) of a representative sample (up to 1,000 pieces per species group) of your finished lumber. We note all potential visual downgrades to each piece for later analysis to determine whether downgrades can be economically reduced by changing operational parameters such as wane allowance or target sizes.
The results of the tests are factored to represent a short span E (Short span E is measured by most MSR machines) and tabulated to give:
- expected grade yields by:
- species and
- lumber size
- grade lost due to defects such as:
- cross section knots/grain distortion
- slope of grain
Economic payback analysis uses historical MSR premiums and projected additional production costs to evaluate the viability of installing MSR equipment.
Lamination Stock Yields
Production of lam stock (to be used in glue-laminated beams) is normally begun with very disappointing grade yields. Lam stock is a very demanding product with very strict requirements for manufacturing defects such as:
- Sizes (e.g. less than 0.008" variation in thickness)
- Moisture content and moisture variation, and;
Although there are many natural defects that affect lam stock grade yields, losses due to the above manufacturing problems generally account for up to one half of the downgrades. Most of these losses are recoverable!!
Our experience with troubleshooting manufacturing problems with lam stock means that we can evaluate:
- Potential lam yields in your operation
- Quality control procedures
- Different kiln schedules
- Operator training
- Operating costs to improve yields (LRF changes and kiln capacity constraints)
- Small capital projects to improve yields (planer repairs, etc.)
We also have extensive experience in working with mill personnel to train them to get the most from their lam stock program.
For more information, e-mail us at