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Going, going, gone! The making of a baseball bat.

Every year millions of people visit ballparks worldwide to cheer on their favorite little league, high school, college, or major league teams while partaking in what may be considered one of America's favorite pastimes: baseball. Players such as Babe Ruth, Jackie Robinson. Joe DiMaggio, Sammy Sosa, Mark McGwire. and many others have created millions of baseball fans worldwide with the crack of their bats and their playing agility (Figure 1).

From little league players to professional athletes, baseball has become a sport that is not only fun to play and watch, but also a sport driven by innovation and technology. One particular piece of baseball equipment that has undergone many changes is the baseball bat. Prior to the early 1970s. wooden bats were the only choice available. Today, players have a variety of bats made from different materials from which to choose. This article will delve into the manufacturing process of wood and metal baseball bats. It will also explore the various types of woods and alloys used in making baseball bats as well as new metal bat regulations.


During the early 1900s baseball bats were made of wood and differed from the bats used today. For example, the first bats were not as tapered in the handle of the bat, and they were heavier (Kelley, 2000). Their shape has evolved over the years to improve the bat's performance. A Louisville Slugger is perhaps one of the most recognized baseball bats in baseball today. According to Louisville Slugger (2012), it has sold more than 100,000,000 bats over the past 120 years. It is still the preferred bat for the major leagues, accounting for 60 percent of wooden bats used today.

The story of the Louisville Slugger began with seventeen-year-old John A. "Bud" Hillerich, who worked in his father's woodworking shop in Louisville, KY in the 1880s. Bud, an avid baseball player, left work one afternoon in 1884 to watch the Louisville Eclipse, a local baseball team. Pete Browning, one of the stars of the Louisville Eclipse, was in a hitting slump and broke his bat in frustration. Bud offered to make Pete a new bat. Bud and Pete went over to the shop, and Bud handcrafted a new wood bat from a long slab of wood using Browning's advice and specifications, a wood lathe, and turning chisels such as shown in Figure 2. Using his new bat, Browning was able to get three hits the next day (Louisville Slugger, 2012).

As word got out about Pete's new bat, professional ballplayers sought out Hillerich's shop to make new bats for them. J. F. Hillerich, Bud's father, had little interest in making wooden bats, as he believed the company would be more lucrative in making stair railings, porch columns, swinging butter churns, and other wood items. Many players were initially turned away. Bud, who saw a future in bat making, persisted, and his father conceded to his son's vision (Louisville Slugger, 2012).

According to Louisville Slugger (2012), in 1894 Bud Hillerich registered the name "Louisville Slugger" with the U.S. Patent Office after taking over the company. In a new sports-marketing concept in the early 1900s, Hall of Fame hitter Honus Wagner was paid for the use of his name on a bat. This practice continues today with many professional athletes. According to Louisville Slugger (2012), by 1923 they were selling more bats than any other bat maker in the country, and baseball had grown into the most popular sport in the nation. Babe Ruth, Ty Cobb, and Lou Gehrig are just some of the baseball legends that have used Louisville Sluggers (Louisville Slugger, 2012).


Louisville Sluggers are made of two kinds of wood: white ash and maple (Louisville Slugger, 2012). According to an interview conducted by Terdiman (2008) with Louisville Slugger bat maker Danny Luckett, Louisville Sluggers at one time were made primarily from white ash. Today, however, half of the major league bats made by Louisville Slugger are maple, thanks in part to Barry Bonds who in 2001 broke the single-season home run record using a bat made from maple wood (Terdiman, 2008).

Louisville Slugger has evolved its process of making bats from a purely handmade process to one that primarily utilizes machinery (Figure 3). The process begins by selecting the best ash and maple trees from the northeast section of the U.S. (Louisville Slugger, 2012). Ash and maple are the woods of choice for Louisville Sluggers for several reasons. Ash is considered a strong timber and can be lighter in weight than maple (Louisville Slugger, 2012). Ash, unlike maple, has a unique flexible quality; however, it tends to flake or delaminate after extensive use (Louisville Slugger, 2012). Maple is a denser, heavier wood than ash, which keeps it from flaking. A drawback of using maple is that its density tends to make it heavier, thereby making it difficult to make a lightweight bat--especially in a big-barrel variety (Louisville Slugger, 2012).

Once the trees are cut down and stripped of all branches, they are trucked to a facility where they are cut down or "cored" into cylinder-shaped wood. These cylinders are now called billets. They measure approximately 37 inches long and 2.75 inches in diameter. They are placed on computer numerical control (CNC) machines, which are operated by experienced bat makers, and cutting begins (Terdiman, 2008).

The CNC machine makes higher-grade bats such as those used in the major leagues. Prior to using the CNC machine, specialized lathes were used to make bats. Louisville Slugger still uses lathes for making bats of lower quality levels or for souvenirs and other uses. The process takes only seconds to convert a billet into a bat, whereas in the old days the process would take about fifteen minutes to carve out a bat by hand (VOA, 2010). Once the bats are processed, they are either branded, or a "pressure-applying" process is performed to apply the company logo. The bats are then lacquered or painted and hung to dry. If a player is under contract with the company, his/her name is etched onto the bat. The bats are then ready for packaging and delivery to the player or sold to fans (Terdiman, 2008).

Although the bat-making process is now reliant on technology to drive manufacturing, there are still skilled bat makers at the facility who understand what Louisville Slugger craftsmanship is all about. The bats must meet their strict quality standards after being manufactured. The process of making a metal bat is very different and involves different technologies than that of the wood bat-making process. In the last two years, the metal bat industry has undergone changes to ensure the safety of players and to make the game more competitive.


Technology and engineering drive baseball-bat manufacturers to always look for ways of improving their bats so players can have a hitting advantage. Metal bats have come a long way from when they were first introduced in the 1970s. The first actual patent for a metal bat came from William Shroyer in 1924; however, the first official aluminum bat to be used in a baseball game was made by a Missouri company called Worth Sports in 1972. In 1974, Worth introduced the first aluminum bat for the National Collegiate Athletic Association (NCAA). As aluminum bats grew in popularity, many companies began looking for newer and better-performing metals and alloys from which to construct bats (Sawyer, 2012).

In 1993, a titanium bat was introduced and subsequently banned. According to Russell (2005), titanium can provide a high strength-to-weight ratio, which provides durability and can provide a thinner single-walled bat than is possible with aluminum. Russell (2005) noted that titanium greatly increased the ball exit speed upwards of 10 mph faster (about 40-50 feet farther than that of aluminum bats. Player safety became a con cern. For this reason, titanium bats became illegal for use in NCAA-sanctioned games.

Alloys common to metal bats include zinc, copper, and magnesium, which are commonly known as 7046, the standard aluminum alloy for bats. A more durable alloy used is CU31/7050, comprised of zirconium and increased levels of magnesium and copper. An even stronger alloy mix is C405/7055--comprised of larger amounts of zirconium. Other choices include C555, comprised of scandium traces and making it seven times stronger than C405 (Oakes, 2010).

In 1996, DeMarini, another bat manufacturer, introduced a new kind of bat with a double aluminum wall, which was said to improve the bat's performance versus a single-wall aluminum bat. In 2001, Louisville Slugger introduced the first composite bat manufactured from fiberglass, graphite, Kevlar, and resin. Finally in 2006, bat manufacturer Easton also designed a composite bat called the Stealth CNT out of carbon-nanotube-reinforced resin that reduced bat weight (Sawyer, 2012).

As new technologies and alloy combinations emerge, newer and more improved metal bats are being made available to players of varying skill levels. It is hard to imagine that a high-tech baseball bat is formed from a small piece of metal about the size of a small can. The process for making a metal bat is constantly improving and becoming more efficient with improved innovations.


Metal bats, which are essentially metal tubes, come in many shapes, weights, and materials. In the eyes of a baseball player, a metal bat can provide a valuable hitting advantage. The processes of making a metal bat can vary, depending on the materials and which company is manufacturing it. In this section, the focus will remain on the aluminum bat-making process that is unique to the Hillerich & Bradsby Company.

The making of an aluminum bat begins with aluminum tubing in diameters between two and three inches, which are cut to lengths from 24 to 35 inches. The tube then undergoes a process known as "ironing." During this process, the precut tube is slid over a tapered mandrel using hydraulic pressure, which forces it onto a die, producing a hollow tube--the top portion of the bat. This process makes the metal harden because it involves working the aluminum without the presence of heat. An annealing treatment is performed before further processing can occur (Cole & Lundin, 2003).

The next process, known as "swaging," involves annealing the hollow tube and is processed by two opposing dies that rotate around it, causing 5,100 impacts per minute at a rate of 850 revolutions per minute. This reduces the diameter of the bat and allows for less metal in the making of the handle. The swaging process can decrease the diameter of the bat, which can affect quality. For this reason, Hillerich & Bradsby Company uses a mandrel to control the diameter and thickness from the barrel to the handle. Following the "swaging" process, the bat undergoes a cleaning process to remove any lubricants remaining from the "ironing" process (Cole & Lundin, 2003).

The aluminum bat is next hardened using a molten salt bath solution, which heats the bat to approximately 900 degrees Fahrenheit for twenty minutes. At this temperature, the elements that make up the bat's selected alloys become soluble and go into a solution within the matrix of the material. In other words, the alloys combine to create a stronger surface. Once this process is complete, the bats are quenched in a water tank that creates a supersaturated solution to prepare the bats for "precipitation aging," which completes the hardening process. In precipitation aging, the bats are reheated in an "aging" furnace for approximately 12 hours at 300 degrees Fahrenheit. This process causes the alloying elements to precipitate and form grains of a particular size and shape, thus a producing harder and stronger material (Cole & Lundin, 2003).

By this stage, the bat is nearing completion, and the aluminum cylinder now looks like an actual bat, with the exception of the top end and handle. Depending on which bat is being processed, there are two ways of sealing the top end: spinning or capping. If the bat is spun, then an end-spinning machine rotates the bat at 1600-1800 revolutions per minute while heated to 400 degrees Fahrenheit. As this is occurring, a forming tool is pressed against the end of the bat, forcing the softened metal to seal over the opening. If a cap is used, an end cap is grooved internally, ensuring the caps fit precisely over the opening and causing it to securely seal shut. Once sealed, the bat moves on to polishing. In this phase, the bat is fed into a machine that causes the bat to rotate as it is being polished. There are several polishing grits used in the polishing process, which are dependent on the type of bat being manufactured (Cole & Lundin, 2003).

To finish the manufacturing process, bats are silkscreen-printed with company logos and bat names. Materials used in screening processes are meant to be abrasion-resistant and will not rub off on a ball. Anodized bats are silkscreen-printed immediately after the anodizing process and dyed. The bat is sealed with a special sealant that protects the dye. Some bats undergo a process of injecting polyurethane foam made up of liquid resin, catalysts, and blowing agents into the barrel of the bat through the handle. A chemical reaction leaves flexible urethane foam inside the bat barrel. Other bats are treated with other materials to add weight depending on the models. All bats are weighed to ensure they are the proper weight (Cole & Lundin, 2003).

The final process involves cleaning and welding of the handle. The bats are sent into an automatic welding booth where a machine attaches the knob at the end of the bat handle. The bats either receive a rubber grip, which is applied by air-pressure, or a wrap grip, which is done by hand. The bats are then sent into a final assembly area where they are packaged and labeled prior to shipping (Cole & Lundin, 2003).

Metal bat manufacturers have had to contend with new certification regulations as of 2011. Bats must comply with NCAA rules in order to be used in games. In the past several years, bats were tested using ball exit speeds (BESR). As of 2011, bats are to be tested and certified using a formula called BBCOR, or ball-bat coefficient of restitution. BBCOR bats are changing the landscape of baseball and producing a more competitive game. Games that were once won by multiple home runs as a result of metal bats now rely more on defensive and offensive player tactics to secure a win rather than out-of-the-park home runs.


Metal bat technologies have grown into a multimillion dollar industry rivaling that of the wooden bat industry. Although metal bats of the 1970s were not without flaws, cutting-edge technology involved in making metal bats is quite impressive in producing newer and better-performing bats. With this new technology come questions and concerns regarding the safety of players and bat performance.

Controversy and changes are currently affecting metal baseball-bat usage. The NCAA has issued a change in approved bats for games, stating that a metal bat used in play must be BBCOR (Bali-Bat Coefficient of Restitution) tested and certified as of January 1,2011 (NCAA, 2008). Metal bats were creating a very fast ball that for baseball fans meant home runs, but for players meant the possibility of injury because the exit speed of the ball coming off the bat was greatly increased. This was known as the "trampoline effect" in BESR (Ball Exit Speed Ratio measured) bats.

The "trampoline effect" is described by Crisco, Greenwald, Blume, and Penna (2001) as an elastic deformation when the ball comes in contact with the bat. They state there is less of a deformation of a ball upon impact with the bat, which creates less energy loss in the ball and higher batted ball speed potential. This "trampoline" effect does not occur in wooden bats and is illustrated in Figure 6.

According to a study on baseball-related injuries from 2005 through 2007 conducted by Collins and Comstock (2008), among all youth sports in the U.S., baseball has resulted in the most sports-related facial injuries. Injuries requiring medical attention, such as severe eye injuries and dental injuries, are just some of the injuries noted in the study (Collins & Comstock, 2008). Metal bats have had to undergo a change in the last two years to improve safety. The changes were also sought to bring a balance back between team offenses and defenses on the field.

Prior to 2011, bats were measured by the NCAA using BESR formulas. Russell (2008) defines this as the ratio of the speed with which the ball exits the collision divided by the combined speeds of the bat and ball before the collision. Accordingly, For [the BESR test] (which follows the ASTM standard F2219114]), a baseball is fired from a cannon at a speed of 138-mph towards a bat which is initially at rest (vbat=0), gripped in pivot that is free to rotate after the ball hits the bat. The speeds of the ball as it approaches the bat and as it rebounds from the bat are measured with a series of light gates (para. 38).

Russell (2008) describes that BESR is first calculated from this equation where v is equal to velocity:

BESR = [V.sub.exit]/[V.sub.ball] + [V.sub.bat]

According to Russell (2008), this can be interpreted as "the ratio of the speed with which the ball exits the collision divided by the combined speeds of the bat and ball before the collision. Thus, the name Bali-Exit-Speed-Ratio" (para. 8). The equation then becomes (with v bat = 0, or the ball initially at rest):

BESR = [V.sub.exit]/[V.sub.ball]+[v.sub.bat]

Russell (2008) goes on to state:

"The measured exit speed of the ball will depend on whether or not the bat and ball are initially moving or initially stationary, but the value of the BESR and eA [the collision efficiency] will be the same (para 39).

Unfortunately, one of the problems with this "ball-in, ballout" method is that bats moments-of-inertia below 7000 ozin (2) tend to have extremely low collision efficiency (or BESR) so that they often don't rebound with enough speed to pass through the ball speed gates. A possible fix to this problem is to measure the bat rebound speed after the collision and to use this to determine the BESR (para 40)."

The new BBCOR-measured bats are designed with this in mind. A BBCOR bat is designed to absorb much of the power coming from the ball by reducing the "sweet spot" of the bat, minimizing the 'trampoline effect." BBCOR-measured bats should perform more like wooden bats. A BBCOR bat, according to the NCAA Standard for Testing Baseball Bat Performance, Bat-Ball Coefficient of Restitution (2009) standards, will employ the following formula, which is calculated using the inbound (I) and rebound (R) speeds of the ball (Cball is the correction factor allowed):

BBCOR= [V.sub.R]/[V.sub.I](l+r)+ r + [C.sub.ball]

BBCOR bats are tested by the NCAA using ASTM F2219, Standard Test Methods for Measuring High-Speed Bat Performance. A detailed explanation of how the NCAA performs testing procedures to certify BBCOR bats can be found at NCAA%20BBCOR%20Protocol%20FINAL%205%2009.pdf.

The new BBCOR bats have had a significant impact on baseball. According to the NCAA (2011), college level home runs have been slashed by almost half in midseason statistics, averaging 0.47 per game in 2011 compared to 0.85 home runs per game in 2010. The NCAA (2011) also reports that the overall batting average has dropped from .301 (2010) to .279 (2011); ERA (earned run average) from 5.83 (2010) to 4.62 (2011); and the number of shutouts (a game in which one team prevents the opposing team from scoring) has jumped from 277 (2010) to 444 (2011) in midseason statistics.

These statistics clearly show the impact BBCOR bats are having on the game of baseball. There are those who support the new bats, and there are those who crave the power that old BESR bats offered. Regardless of player preference, the new BBCOR bats are keeping more balls in the park, allowing defensive players to showcase their playing ability.


The activities presented here align with ITEEA's Standard 19 (Manufacturing Technologies) (Standards for Technological Literacy: Content for the Study of Technology, ITEA/ITEEA, 2000, 2002/2007). BBCOR-certified bats are dramatically affecting the game of baseball today. Have students split up into groups and research baseball statistics such as home runs and earned batting averages using the NCAA website at

Have students create a presentation that shows how, through the evolution of metal baseball-bat technology, the game has been impacted. They can recreate the trampoline effect using a three-dimensional model or create a virtual timeline of bat materials and game-scoring impacts.

An informational resource for additional class activities is a website by Dr. Daniel Russell of Pennsylvania State University. He offers a comprehensive baseball website offering articles and extensive research on the physics and acoustics of different bats. His website address is


Baseball bats have come a long way. Their manufacturing process has evolved from a highly skilled handmade process to an automated manufactured process using some of the latest computer-controlled technology and engineering available. Players will often seek out newer and better bat alternatives to those they currently use, keeping this game reliant on innovation. As the game continues to thrive, so will the desire to create faster, stronger, and more innovative baseball bats that provide players with hitting advantages. With the right bat in their hands, players strive to hear, "It's going, going, gone over the fence!"

REFERENCES (2012). Anodizing: The finish of choice. Retrieved from is anodizing.html (n.d.). Definition of supersaturated solution. Retrieved from supersaturated+solution.php

Cole, K. & Lundin, E. (2003). Batter up/Turning an aluminum tube into a baseball bat. Retrieved from www.thefabricator. com/article/tubepipefabrication/batter-up-turning-an-aluminum-tube -into-a-baseball-bat

Collins, C. & Comstock, D. (2008). Epidemiological features of high school baseball injuries in the United States, 2005-2007 Pediatrics 121(6) 11R1.11-7

Crisco, J., Greenwald, R., Blume, J., & Penna, L. (2001). Batting performance of wood and metal baseball bats. Journal of Applied Biomechanics, 17(3), 241-252

Sawyer, H. (2012). The next big hit. Popular Mechanics, 189(5), 25-26.

International Technology Education Association (ITEA/ITEEA). (2000/2002/2007). Standards for technological literacy: Content for the study of technology. Reston, VA: Author.

Kelley, J. (2000). Baseball. New York, NY: Dorling Kindersley, Inc.

Louisville Slugger. (2012). History. Retrieved from, html

Louisville Slugger. (2012). Performance technology. Retrieved from

National Collegiate Athletic Association. (2008). Bat performance measurements memorandum. Retrieved from rules/baseball/bats/NCAA.BBCORannouncement.9.05.pdf

National Collegiate Athletic Association. (2009). NCAA standard for testing baseball bat performance, bat-ball coefficient of restitution. Retrieved from %20FINAL%205%2009.pdf

National Collegiate Athletic Association. (2011). Halfway home: homers, scoring down. Retrieved from baseball/2011-04-07/halfway-home-homers-scoringdown

Oakes, R. (2010). What is in an aluminum bat? Retrieved from

Russell, D. (2008). Explaining the BESR performance standard for NCAA baseball bats. Retrieved from drussell/bats/besr.html

Russell, D. (2005). Why are titanium bats illegal? Retrieved from

Nathan, A., Russell, D., & Smith, L. (2004). The physics of the trampoline effect in baseball and softball bats. Engineering of Sport, 5(2), 38-44.

Terdiman, D. (2008). Making bats the Louisville Slugger way. CNET News. Retrieved from 830113772_3-9973182-52.html

Voice of America (VOA). (2010). German immigrant family makes famed Louisville Slugger bat, [Video File]. Retrieved from

Diana Cantu is a Ph.D. student at Old Dominion University studying Elementary STEM Education. She can be reached at dcantO05@

Figure 2. Technology and Engineering Vocabulary. These are key words used within the article.


Alloys--the different elements/metals added to change an existing metal's composition.

Anneal--when a metal is hardened, heat is applied to the metal to make it "softer," or easier to work with (Cole & Lundin, 2012).

Anodized--an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized (, 2012).

BBCOR--Bali-Bat Coefficient of Restitution. The new test regulation used by the NCAA.

BESR--Ball Exit Speed Ratio. Prior to 2011, the exit speed of the ball upon impact with a bat was how the NCAA tested and certified bats.

Die--specialized tool used in manufacturing to cut or shape material using a press.

Lathe--a machine tool that rotates an item on its axis so that it can be shaped, cut, or sanded.

Mandrel--a cylindrical rod around which metal or other material is forged or shaped (Cole & Lundin, 2012).

Supersaturated Solution--A solution that contains a higher than saturation concentration of solute (, n.d.).
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Author:Cantu, Diana
Publication:Technology and Engineering Teacher
Geographic Code:1USA
Date:Oct 1, 2012
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