The first metal baseball bat was patented in 1924 by William Shroyer, but did not become popular until the Worth Bat Company produced the first aluminum bat in 1970 (which was soon made stronger and lighter by Easton). These stronger, lighter, aluminum bats quickly became popular across the United States, and in 1993 both Easton and Worth introduced bats made of titanium. In 1995, Easton and Louisville Slugger further refined their aluminum bats to make them lighter and stronger than ever. Today, aluminum bats are widely used by amateur baseball and softball players.
Aluminum baseball bats are currently prohibited in Major League Baseball. This has been done for reasons of safety and competition. Modern aluminum bats have been highly engineered, using special blends of metals and alloys, resulting in much faster exits speeds for a baseball than when hit with a wooden bat.
Aluminum bats are allowed by the high school and college athletic associations in the United States, but have restrictions placed on them. Bats used in high school and college games must be 3 ounces less than the length of the bat, and may not exceed 2 5/8 inches in diameter at the thickest part. They must also be "Ball Exit Speed Ratio" (BESR) certified. However, the NCAA is switching to a new, more accurate, certification process for the 2011 season.
Aluminum bats are more durable than wood bats (which can break when the ball hits close to the handle) and have better weight distribution, resulting in faster swings, and thus greater power. Aluminum bats also come with warranties, unlike wood bats, and can be less expensive to own and use.
Many purists advocate the use of wood bats because they are the classic bat with which the game of baseball has been played. Wood bats are also much safer than aluminum bats, as the ball does not leave the bat with the same speed that it leaves an aluminum bat.