Search the RTI Website
  
Click here for information on how to donate to the Rural Technology Initiative
Click to go to the RTI Home page
Click to go to the About RTI page
Click to go to the RTI Projects page
Click to go to the RTI Publications page
Click to go to the RTI Tools page
Click to go to the RTI Geographic Information Systems page
Click to go to the RTI Streaming Video Directory
Click to go to the RTI Training page
Click to go to the RTI Contacts page
Click to go to the RTI Image Archive
Click to go to the RTI Site Map
Click to go to the RTI Links page


Chapter 5.  Veneer and Plywood

Measurement                                                                         

      Standard Reporting Basis                                                 

            •Square foot 3/8 inch basis                                          

            •Square meter, 1 mm basis                                          

            •Imperial to metric conversion factors                        

      U.S. Softwood Veneer and Plywood                               

           • Veneer sheet thickness                                               

            •Veneer sheet width                                                    

            •Veneer sheet length                                                    

            •Plywood panel sizes                                                  

            •Volume of veneer or panels                                       

                1.  Converting surface measure of any thickness to the 3/8 inch basis

                2.  Cubic foot calculation

                3.  Cubic meter calculation

      Hardwood Veneer and Plywood                                      

            •Veneer sizes                                                               

            •Plywood panel sizes                                                  

            •Volume of veneer or panels                                       

Recovery Efficiency                                                              

      Material Balance Green-End Recovery                            

            •From mill studies                                                       

            •Theoretical material balance                                       

      Material Balance Dry-End Recovery                               

      Recovery Efficiency Measures                                        

            •Cubic recovery ratio (CCR)                                       

            •Veneer recovery factor (VRF)                                   

            •Relationship between CRR and VRF                        

            •Veneer recovery and board foot log scale                  

Weight of Veneer and Plywood                                             

 

Chapter 5.  Veneer and Plywood                                                         

Measurement

Standard Reporting Basis

Square Foot 3/8 Inch Basis (SF3/8).     In North America, statistics on veneer, plywood, and other panel products (Chapter 6) are generally reported as the number of square feet, or surface measure, of a stated thickness. Due to the variety of thicknesses available, surface measures are not directly compa­rable. Hence to facilitate accounting and reporting, statistics are commonly expressed on a standard­ized thickness basis. For veneer and plywood, this standard thickness basis is 3/8 inch. Plywood and veneer volumes are usually measured dry (2 to 5% MCod). For other panel products, covered in Chapter 6, the standard thickness basis may be 1/8, 3/8, 1/2, or 3/4 inch depending on the category of panel. Table 5-1 lists a number of common panel thick­nesses and factors to convert them to one of the four standard thickness bases.

Square Meter, 1 mm Basis.     The standard basis for reporting plywood and veneer in countries on the metric system is the square meter, 1 mm basis. This represents a piece 1 m square and 1 mm thick, or 1/1,000 cubic meter.

Imperial to Metric Conversion Factors for Plywood.     Table 5-2 presents commonly used conversions.

U.S. Softwood Veneer and Plywood

Veneer Sheet Thickness.     Softwood veneer thicknesses usually range from 1/16 to 5/16 inch, with the most common being 1/10, 1/8, and 1/6 inch. Thicknesses are often expressed by mills in thou­sandths of an inch. The lathe setting is some­what larger to account for compression during peeling, peeling variation, and shrinkage during drying.  Procedures to calculate the green target thickness at the lathe are similar to those for lumber ex­plained in Chapter 4 (pp. 58-59).

Veneer Sheet Width.     Assuming the common 4 foot plywood panel width, veneer is manufactured in the following nominal widths: 48 inches (full), 24 inches (half), and strip (narrow strips above a minimum salvage size, often 6 inches). Other widths may be produced to correspond to other panel sizes, as shown in Table 5-3. To allow for shrinkage of veneer during drying and trimming of finished plywood panels, these widths are increased to develop target values on machinery.  Thus a mill's green clipper may produce full and half widths as 54 and 27 inches respectively. Actual practice will vary from mill to mill based on quality control and other factors.

Veneer Sheet Length.     When veneer is obtained from a lathe, veneer length exceeds that of a finished plywood panel. For example, on the common 8 foot lathe, the veneer is initially about 100 to 104 inches long. This oversize length allows for shrinkage when the veneer is dried and for panel trimming. The actual log (block) peeled is somewhat longer than the length of veneer. Veneer lengths correspond to panel lengths shown in Table 5-3.  The most common length is 96 inches (8 foot plywood). Crossband widths are half that length. The lineal footage of the veneer ribbon produced from a lathe can be estimated by dividing the square footage by the veneer length.

Plywood Panel Sizes.     Table 5-3 presents the dimensions of softwood plywood  according to U.S. Product Standard PS 1-83. The most commonly produced panel size is 4 by 8 feet in various thick­nesses.

Volume of Veneer or Panels:

1.  Converting Surface Measure of Any Thickness to the 3/8 Inch Basis.    To convert surface measure of veneer or plywood of some thickness (SMt) to the 3/8 inch basis (see Example 1), divide the actual thickness (t) in inches by 3/8 inch (t / 0.375 inch) and multiply by the surface measure:

        SF3/8= SMt * (t / 0.375) = 2.667 * t * SMt.

Column 4 of Table 5-1 lists values of t/0.375.

        Veneer is marketed on the basis of nominal dimensions; the square footage of 1/10 inch full sheets is generally calculated on the basis of nom­inal dimensions such as 4 by 8 feet and excludes the oversizing required for trim and shrinkage.  To estimate the total wood fiber represented, increase the square footage by about 12% (Fahey 1987) or measure a sample of sheets and calculate the adjustment factor needed.
 

Table 5-1. Conversion of actual panel thickness to standard thickness basis.

Actual Thickness

  

Conversion to

  
               

(in)

(mm)

1/8 inch basis

3/8 inch basis

1/2 inch basis

3/4 inch basis
 

(1)

(2)

(3)

(4)

(5)

(6)

  

1/8

3.18

1.0000

0.3333

0.2500

0.1667

  

3/16

4.76

1.5000

0.5000

0.3750

0.2500

  

1/4

6.35

2.0000

0.6667

0.5000

0.3333

  

5/16

7.94

2.5000

0.8333

0.6250

0.4167

  
 

3/8

9.53

3.0000

1.0000

0.7500

0.5000

  

7/16

11.11

3.5000

1.1667

0.8750

0.5833

  

1/2

12.70

4.0000

1.3333

1.0000

0.6667

  

9/16

14.29

4.5000

1.5000

1.1250

0.7500

  

5/8

15.88

5.0000

1.6667

1.2500

0.8333

  
 

11/16

17.46

5.5000

1.8333

1.3750

0.9167

  

3/4

19.05

6.0000

2.0000

1.5000

1.0000

  

13/16

20.64

6.5000

2.1667

1.6250

1.0833

  

7/8

22.23

7.0000

2.3333

1.7500

1.1667

  

15/16

23.81

7.5000

2.5000

1.8750

1.2500

  
 

1

25.40

8.0000

2.6667

2.0000

1.3333

  

1-1/16

26.99

8.5000

2.8333

2.1250

1.4167

  

1-1/8

28.58

9.0000

3.0000

2.2500

1.5000

  

1-3/16

30.16

9.5000

3.1667

2.3750

1.5833

  

1-1/4

31.75

10.0000

3.3333

2.5000

1.6667

  
 

Source:  Calculated by the author.

Table 5-2. Imperial-metric conversion factors for plywood.

From / To:

SF, 3/8

m2, 1 mm

MSF, 3/8

1,000 m2, 1 mm

ft3

m3

SF, 3/8

1

0.885

0.001

0.000885

0.03125

0.000885

m2, 1 mm

1.130

1

0.001130

0.001

0.035315

0.001

MSF, 3/8

1,000

885

1

0.885

31.25

0.885

1,000 m2, 1 mm

1,130

1,000

1.130

1

35.315

1

ft3

32

28.318

0.032

0.0283

1

0.0283

m3

1,130

1,000

1.130

1

35.315

1

Source:  Calculated by the author.

Note: The values in the rows for 1,000 m2, 1 mm basis and for m3 are identical since a 1,000 m2 area that is 1 mm thick represents 1 m3 of volume.
 2.  Cubic Foot Calculation.     The volume, in cubic feet, of a single 4 by 8 foot panel of thickness t inches is

        ft3      =  (4 * 8 feet) * t / 12

                   =  32 * t / 12.

Hence the volume of a 1/2 inch thick panel is 1.3333 cubic feet. Substituting other thicknesses results in column 2 of Table 5-4.

        When the 3/8 inch thickness is substituted into this formula, the volume of a 4 by 8 foot panel is exactly one cubic foot. In general, the formula to convert the SF3/8equivalent of any panel thickness to cubic feet is

        ft3    =   SF3/8 * (3/8) / 12

                =   SF3/8/ 32.

        In section 1 above, it was found that 1,500 square feet of 1/2 inch plywood was equivalent to 2,000 square feet on the 3/8 basis. Substituting this into the above formula results in an equivalent of 62.5 cubic feet of plywood. If the formula in section 1, which converts surface measure of any thickness to the 3/8 basis, is substituted for SF3/8, the following general relationship is found

        ft3    =   [SMt * (t / 0.375)] / 32

                =   SMt * t / 12

                =   0.08333 * t * SMt.

This formula directly converts the square footage of any original thickness to cubic feet equivalent. Values of 0.08333 * t are tabulated in column 3 of Table 5-4. The values in column 3 can also be ob­tained by dividing the cubic foot volume of a 4 by 8 foot panel of given thickness (column 2) by 32 square feet per panel. With this calculation, column 3 can be interpreted as the number of cubic feet of panel per square foot of panel of the indicated thickness. See Example 2.

        Since 1,000 square feet (MSF) is a common unit, column 4 reexpresses column 3 in cubic feet per MSF and column 5 converts cubic feet per MSF to cubic meters per MSF. For example, Table 5-4 shows that 1,000 square feet of 3/8 inch plywood is equivalent to 31.25 cubic feet or 0.89 cubic meters. Reciprocals of these values indicate that, for 3/8 inch plywood, there are 0.032 MSF (32.0 square feet) per cubic foot and 1.124 MSF (1,124 square feet) per cubic meter.

        These formulas and methods can be used to obtain the cubic foot volume of finished panels or nominally measured veneer. To determine the cubic foot volume of green veneer needed to make the panel, increase the result by 12% to account for layup and trim losses (Fahey 1987).

3.  Cubic Meter Calculation.     Outside North America, veneer and plywood are produced in metric sizes: width (W) and length (L) in meters, thickness (t) in millimeters. Statistics are normally reported in square meters surface measure (on a 1 mm basis) or cubic meters. Formulas are

        SMt      =   L * W  = surface measure, m2, of original thickness.

        SM1     =   SMt *t = surface measure, m2, 1 mm basis.

        m3          =   SMt* t / 1,000  = SM1 / 1,000.

Example  1

To convert 1,500 square feet of 1/2 inch panels to 3/8 inch basis:

        SF3/8    =   1,500 * (0.5 inch / 0.375 inch).

                    =   1,500 * 1.3333  =  2,000 square feet.

        The value 1.3333 is also found in Table 5-1, column 4, corresponding to 1/2 inch thickness.

To convert 1,000 square feet of 1/10 inch veneer to 3/8 inch basis:

        SF3/8 =  1,000 * (0.1 inch / 0.375 inch)  =  267 square feet.

Example  2

To convert 1,500 square feet of 1/2 inch plywood:

    to the 3/8 basis

        Multiply 1,500 by 1.3333 (column 4, Table 5-1) to get 2,000 ft23/8. This is the same result obtained by the formula in section 1 (and Example 1).

    to cubic feet (four equivalent calculations are shown)

        .  ft3  =  SF3/8 * 32  =  2,000 / 32  =  62.5.

        .  ft3  =  0.08333 * SMt * t  =  0.08333 * 1,500 * 1/2  = 62.5.

        .  Multiply 1,500 by 0.0417 (column 3, Table 5-4)
            to get 62.5.

        .  Multiply 1.5 MSF by 41.7 (column 4, Table 5-4)
            to get 62.5.

    to cubic meters

        Multiply 1.5 MSF by 1.18 (column 5, Table 5-4)
        to get 1.77.

Table 5-3.  Softwood plywood panel sizes.

Width

36, 48, 60 inches

  

Length

60  to 144 inches in 12 inch increments

  

Thickness sanded

1/4  to  1-1/4 inches in 1/8 inch increments

  

Unsanded

5/16  to  1-1/4 inches in 1/8 inch increments over 3/8 inch

  

Tolerances sanded

±  1/64 inch for thicknesses  ≤  3/4 inch

  
 

±  3% for thicknesses  >  3/4 inch

  

Unsanded

±  1/32 inch for thicknesses  ≤  13/16 inch

  
 

±   5% for thicknesses  > 13/16 inch

  

Source:  USDC (1983a).                                             

Note:   Panel thickness is measured at 9% MCod.  Panel sizes other than those specified are available on special order.

Table 5-4.  Standard plywood thickness with conversions to cubic volume.

 


Panel thickness

4 by 8 foot
panel volume


ft3of panel

 


1,000 ft2 (MSF) becomes

  
 

(inch)

(ft3)

perft2of panel

  

(ft3)

(m3)

  
 

(1)

(2)

(3)

  

(4)

(5)

  
 

1/8

0.3333

0.01042

  

10.42

0.29

  
 

3/16

0.5000

0.01562

  

15.62

0.44

  
 

1/4

0.6667

0.02083

  

20.83

0.59

  
 

5/16

0.8333

0.02604

  

26.04

0.74

  
 
 
 
 

3/8

1.0000

0.03125

  

31.25

0.89

  
 

7/16

1.1667

0.03646

  

36.46

1.03