Veneer Usage in Plywood Construction

By T. Kyle Freres and Andrew Witt

Senior Design Spring 1999

Dr. Richard Barr

Background

Freres Lumber Co. Inc. has produced high-quality wood products for over sixty years. Veneers have been the primary focus of production.

Last year the company purchased a plywood mill and began producing plywood panels.

Background (continued)

Plywood panels are made of thin sheets of peeled wood, called veneers.

Veneers from the company’s mills are sent in-house to the plywood mill as well as sold on the open market.

The veneers are “layed-up” on a production line with layers of glue between them.

Plywood Construction Once the desired “ply” and thickness is

reached, the sheets are pressed, trimmed, stacked, and sent to the customer.

The plywood panels are distributed nationally to a variety of customers for structural or decorative purposes.

Problem

Is there an optimal combination of veneers to be used in plywood construction?

Can material costs be lowered by using a linear programming model?

Current Philosophy

The mill has depended on the expertise of its managers since it was purchased.

Veneer combinations have been chosen by managers based on many years of experience.

Essential production figures are known, but in depth calculations have not been the primary concern.

Solution

A Linear Programming Model was constructed in GAMS to model material costs

Material Costs considered: Veneers used in panels Glue usage in panels

Total material cost was minimized

Variables

Veneers 1/10, 1/8, and 1/6 inch

in Fir and Off Species CD 54in CD 27in Fishtail Utility 27in

Constructions Nineteen different

plywood constructions 3/8 in to 3/4 in panels 3 ply to 7 ply panels

Glue cost per panel

Model Example

Calculations

All calculations were performed on “3/8’s” basis.

This is industry standard for both plywood and veneer.

Eg. Veneer price per sheet is “Dollars 3/8’s” 1/8(price)*3 = 3/8’s dollars * (surface area factor)

= 3/8’s $ per thousand surface

Conclusions

The optimal solution value from our model was approximately $1.1 million for the week period.

Actual wood costs for that same period were $707,000, lower than our value.

This was offset by sales of high grade veneer on the market, bringing the actual cost of wood closer to our optimal solution.

Conclusions (continued)

Veneers used in the solution 10firFT 52932 units 10firCD54 68904 10offFT 32868 10util27 39911 8firFT 57602 8firCD54 55974 6firCD54 6468 6firCD27 6468

Conclusions (continued)

Plywood constructions used in solution Ply3- 3ply, 3/8 in Ply4- 5ply, 1/2 in Ply7- 4ply, 1/2 in Ply9- 5ply, 5/8 in Ply15- 5ply, 23/32 in Ply17- 7ply, 23/32 in

Conclusions (continued)

Calculated optimal glue cost vs. actual glue cost we find:

optimal glue cost: $8.5 3/8’s per thousand actual glue cost: $10.19 3/8’s per thousand

Calculated optimal wood cost vs. actual wood cost: optimal wood cost: $218.57 3/8’s per thousand actual wood cost: $190-200 3/8’s per

thousand

Why these figures?

Further Study

This model could only focus on a small piece of a large-scale production operation. Inclusion of more production information could greatly aid the accuracy of the model.

Acknowledgements

We would like to thank the following people for their support and contributions to the project

Wayne Pape: Manager, Freres Lumber Co. Inc. Ted Freres: President, Freres Lumber Co. Inc. Dr. Richard Barr: Professor and GAMS Consultant

Questions Anyone?