properties of white ash used in major league baseball bats. Growth rate was assessed through the number of
standard schedule and a special low heat schedule with controlled air movement. The bending properties of the
The five properties determined in the tests on the bats and bat stock were: number of growth rings per inch, SG
(weight), MOE (bending or flex), MOR (impact resistance), and the area under the load deflection curve. The
data were statistically tested with the level of significance set at 0.05.
The effects of the number of growth rings per inch on the bending properties are evident in the data presented
in Table 1. As the number of growth rings per inch increased, the bending properties tended to increase.
The MOR (Impact Resistance) values for the specimens with 10 or more growth rings are significantly stronger
from the values for less than 10 growth rings.
One possible explanation for the MOR results versus growth rings per inch may be related to the load-carrying
capacity of each growth ring. Each growth ring in five growth rings per inch supports about 20 percent of the
total load. If 1 growth ring in five growth rings per inch fails under a given load, the four remaining growth rings
must support the total load. Each of the four remaining growth rings supports about 25 percent of the total
load. On the other hand, one growth ring failing in 10 growth rings per inch increased the load from 10 percent
to about 11 percent in each remaining growth ring. Each remaining growth ring in the 10 growth rings per inch
has a smaller share of the total load than the remaining growth rings in 5 growth rings per inch.
An indication of impact resistance is found by measuring the total area, after failure, under the load versus
deflection plot created during the three-point bending test. The larger area under the curve may indicate a
higher impact resistance for the wood.
For baseball bats, it is desirable to have a high impact value. The normalized area data indicate that there is an
increase in the normalized area with an increase in the number of growth rings per inch. Generally, the more
growth rings per inch, the greater the impact value/resistance.
Generally, higher SG values result in higher wood strength values. This is a result of more wood substance per
unit volume to resist stress. The average SG of the specimens in Table 1 is 0.62 and this value is slightly higher
than the average value in the Wood Handbook. (3)
Similar to the trend for the number of growth rings per inch in bending properties, there is an increase in the
bending properties with an increase in the SG. These trends are not as evident in the data as trends associated
with the number of growth rings per inch, but an increasing trend is still there. Specimen 1 (Table 1) had the
lowest SG (0.59) and had the lowest normalized area under the bending curve and MOE values. Specimen 5 had
the highest value of SG (0.64), and had the highest value of MOR.
There appears to be a trend in the number of growth rings per inch and the SG. Similar to the other
relationships, there is an increase in the SG for an increase in the number of growth rings per inch, indicating
more cell wall material per unit volume.
There is a relationship between the number of growth rings per inch and the mechanical
properties for white ash baseball bats.
The trends in data show that as the number of growth rings per inch increases, the values for
SG (weight), MOE (bending/flex), MOR (impact value/resistance), and area under the load
deflection curve also increase.
**The results of the study indicate that growth rings per inch, SG, influence the bending
properties of the white ash.
As the number of growth rings per inch and SG [Specific Gravity] (weight) values increase, the
tendency is to have higher average bending properties.
The results of this research provide a baseline for the wood quality needed for other wood species or wood
composites to compete as replacement materials for white ash in professional baseball bats.
White Ash Bats – Wide or Narrow Grain?
Selected quality characteristics of white ash used in professional baseball bats.
By Norton, Allen G.
Publication: Forest Products Journal
Date: Saturday, March 1 2003
The objectives of this project were to determine the effects of growth rate and drying procedures on the bending
properties of white ash used in professional baseball bats.
The number of growth rings per inch, specific gravity, moisture content, and bending properties were determined for each
Bat stock from the same tree was dried by two methods and tested. The average bending strength values for the
conventional steam kiln-dried bat stock were about 8 percent higher than bat stock dried using a special low heat
schedule. As the number of growth rings per inch and specific gravity values increase and as the difference between the
number of growth rings exiting the bark and pith side of the barrel of the bat decrease, the tendency is to have higher
average bending properties.
The average bat produced for the professional level weighs about 32 ounces and is about 34 inches in length. The handle
of a bat has a relatively constant diameter of about 1 inch. The transition from the handle to the barrel of the bat is
tapered and the barrel of the bat has a relatively constant diameter of about 2.5 inches. Major league players may use
between 10 to 12 dozen bats per year.
“Over 20 wood quality control checks are used in the manufacturing of professional baseball bats. This
high number of quality control checks results in a large number of rejects. In fact, only 20 to 25
professional bats, (about 2.5 board feet [BF] per bat billet) will emerge from each 1,000 BF of selected logs
processed to make bats.”
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