1. Composite Baseball Bats
Manufacturing Process & Comparison with Aluminum Bats
Syed Mustijab Haider Rizvi (MM111117)

2. Composite Baseball Bats
Table of Contents
1. Introduction
2. Shapes
3. Aluminum and Composite Bats
4. Properties of Baseball Bats
5. Manufacturing Process
6. Comparison
7. Conclusions
8. References

3. Composite Baseball Bats
Introduction
Baseball bats fall within three material classifications
1. Wood 2. Aluminum 3.Composite

4. Composite Baseball Bats
Shapes
Baseball bats in the early days of baseball came in all
shapes and sizes
(long, short, flat, and heavy)
• 1859 – Maximum diameter 2.5 inches
• 1869 – Maximum length 42 inches
• 1890 – No more flat bats only round with
maximum diameter 2.87inches

5. Composite Baseball Bats
Aluminum and Composite Bats
1924 – A patent for the first metal baseball bat
1970 – First metallic bat in the game
1980 – First composite bat in the game
Worth Aluminum baseball bat Easton Aluminum baseball bat

6. Composite Baseball Bats
Properties of a baseball bat
Important features
Durability and strength
Stiffness
Swing weight
Trampoline effect
Vibrations

7. Composite Baseball Bats
Manufacturing Process
Following steps are involved in composite baseball bat manufacturing
process
1. Starting material 6. Hot pressure molding
2. Steel bat frame 7. Extracting steel bat form
3. Winding of polypropylene layer 8. Inspection and flexibility testing
4. Baking 9. Black primer coating
5. Braided carbon and glass layers 10. Finishing operations

8. Composite Baseball Bats
1. Starting Material
Resin infused pliable carbon fiber sheets
• Sheet layers
• Hot rolling – melting of resin and diffusion of fibers
Sheet layers Hot rolling

9. Composite Baseball Bats
2. Steel Bat Form
The fiber sheets are then spiral around the steel bat form at different angles
to make a fine bat form.
Steel bat form Fiber sheet wrapping on steel bat form

10. Composite Baseball Bats
3. Winding of polypropylene
A layer of polypropylene is winded to squeeze out any trapped air between
the layers
Fiber sheet
wrapped bat
form
Polypropylene
layer

11. Composite Baseball Bats
4. Baking
Baking for two hours  Resin curing
Placing bats in baking oven

12. Composite Baseball Bats
5. Braided carbon and glass layers
After the removal of polypropylene, bat form is wrapped with three layers
(3)
• Braided carbon and glass (1)
• A thick layer of carbon (2)
• Aramid Fiber layer (3)
(1) (2)

13. Composite Baseball Bats
6. Hot Pressure Molding
The bats are placed in the mold and epoxy resin is injected with high
pressure at high temperature
Bats in mold
Hole for
epoxy resin
injection

14. Composite Baseball Bats
7. Extracting the Steel Bat Form
After the removal from the mold steel bat form is extracted
Steel bat
form
Hollow
Composite
bat

15. Composite Baseball Bats
8. Inspection and Flexibility Testing
Bat is inspected for any visible defects and tested on flexibility testing
machine to ensure that bat has attained desired flexibility

16. Composite Baseball Bats
9. Black Primer Coating
After inspection black primer coating is applied and bats are hanged to dry

17. Composite Baseball Bats
10. Finishing Operations
(4)
• Spray Paint (1)
• Brand
• Adjust weight (2)
• Adjust balance
• In-cap (3)
• Grip (4)
(1) (2) (3)

18. Comparison
Comparison of aluminum and composite baseball bats
Composite Aluminum
Swing weight
Lower swing weight and maximum
effect of swing weight by having both
Relatively higher swing weight
a lower moment of inertia as well as a
center of mass closer to the handle
Trampoline effect
The softer barrel allows the ball to Due to isotropic properties it is difficult
come off with small losses in energy to make different parts with different
while maintaining the stiffness of the stiffness so stiffness of barrel must be
bat in the handle high
Vibration
Very high damping rate causing no
High vibrations cause a sting
observable vibrations

19. Comparison
Composite Aluminum
Temperature effect
Cannot be used at lower temperature Can be used at any temperature
Durability
Relatively low life time Can be used for long period of times
Flexibility in properties
Properties can be tailored at will Difficult to obtain anisotropic properties
Performance with time
Performance improves with usage due
Performance decreases with time
to loosing of fibers up till a certain limit
Sweet spot (area of bat which transfer maximum power to ball)
Larger sweet spot Relatively small sweet spot
Cost
High cost Low cost

20. Composite Baseball Bats
Conclusion
Composite bats have outperformed aluminum bats by their superior and tailor
able qualities;
• The swing weight for these bats is more easily controllable,
• Trampoline effect may be tuned,
• Bending stiffness may be tuned and
• Bending vibrations are more highly damped.
These all properties together made them the first choice of any player

21. Thank You!

22. References
[1] Mahesh M. Shenoy et al (2001). “Performance assessment
of wood, metal and composite baseball bats”, Composite
Structures 397-404
[2] Matthew Broe et al (2010). “Experimental study of the
evolution of composite baseball bat performance”, Procedia
Engineering 2 2653–2658
[3]http://www.baseball-bats.net/baseball-bats/baseball-bat-
history/index.html 18-05-2012 at 1:45 PM
[4]http://americanarmchaircricketer.blogspot.com/2012/02/goi
ng-batty-or-what-are-those-sticks.html 18-05-2012 at 2:00 PM
[5]http://www.bplowestprices.com/easton-sv12-bsv1-baseball-
bat-high-school-adult-3.html 18-05-2012 at 2:25 PM
[6] http://www.woodbat.org/ 18-05-2012 at 4:00 PM
[7]http://science.discovery.com/search/results.html?focus=site
&query=baseball+bats&search= 18-05-2012 at 5:00 PM