Beneath the Label

New technologies are changing the science of the baseball bat design.
Chris Gorski, Editor

(Inside Science) -- Whether it is the legendary crack of a wood bat, the ping of a metal one, or even the thunk of a new composite stick, baseball season is underway and the sound of a bat hitting a ball can be heard in almost every U.S. city. Professional players use wood bats, but for the more than 40 million amateur players stepping up to the plate every game, the carnival of bats now available can boggle the mind. Read the labels and an unrecognized language beckons: Quad wall, scandium alloy, composite and nanotechnology. This is baseball?

"There's a whole lot more to a bat than a person would think," said Lloyd Smith, a mechanical engineer and director of the Sports Science Laboratory at Washington State University in Pullman. The flexibility of the bat handle, the strength of the barrel, the material it's made from, and the size of the all-important sweet spot are all factors that bat designers can manipulate. These and other variables combine to create a tool specialized for striking baseballs and softballs.

Designing a bat begins with the material. Calin Thomas, a marketing manager at Easton Sports, in Van Nuys, California, explained that the company focuses on aluminum alloys and composites made of carbon and glass fibers for their bats. "We focus on the criteria of performance, durability, and feel,” he said. This includes using high performance alloys to increase the size of the prime hitting area of metal bats and adding impossibly small pieces of carbon called nanotubes to increase the durability of the resin in composite bats.

What happens when a bat hits a ball depends on the type of bat doing the hitting. As every player learns in the first year of Little League, the best place to hit a ball is on the so-called sweet spot, the fat part of a bat, so that the least energy is lost from the collision. Batters want the energy they put into their swing to be applied directly to the ball. Hitting a slow change-up with the far end of the bat or a hard fastball near the handle will cause the bat to vibrate, sometimes violently, as is confirmed by young players shaking the pain out of their hands on the way back to the bench. In addition to stinging the hitter's hands, this indicates that energy from the collision of the bat and ball has not been applied to propelling the ball into the field.

When wooden bats strike a ball, the ball compresses severely and, according to Smith, "the wood compresses very little. You could almost say that the wood deforms not at all." The ball loses energy by deforming, but the solid wood bat doesn't deform and passes its energy to the ball. He said he's seen high-speed video depicting balls "almost wrapping around the bat."

Constructed from hollow shells of material, aluminum alloy bats and composite bats react differently. Smith said, "with a hollow metal bat, that ball is going to deform less, which means it's dissipating less energy. The bat deforms more, but it takes that energy and returns it elastically back to the ball." This is called the trampoline effect. Making bats with thin, flexible walls can enhance this effect - but it means that metal and composite bats can be affected by temperature. In fact, Easton recommends not using aluminum bats in temperatures below 50 degrees Fahrenheit. At low temperatures the ball is denser and can dent bats, especially high performance models with thin walls. High temperatures can also damage bats.

The qualities of hollow bats make it possible to design them to outperform wooden bats. In fact, manufacturers have been so successful that the different organizations that oversee youth, college, and adult baseball and softball "have been obliged to come up with test methods to put a limit on how high the performance of these bats actually reaches," said Smith. Part of the concern is that if a bat is too powerful it can smash a violent, possibly life-threatening, line drive back at the pitcher, who is only 60 feet away in teen and adult baseball leagues, 46 feet on Little League diamonds, and 43 feet for college softball.

Smith said that in slow pitch softball "if everybody had the highest performing bat that could be designed, well, everybody would be hitting home runs." The safe speed of a batted ball is hard to define, but most people can agree that the excitement of homeruns would wane if every other pitch flew over the outfield fence.

As in any industry, marketing plays a role in selling baseball bats. The newest technology might be better, but it might also be part of the techniques used to make one bat stand out on the rack. New technologies allow the manufacturers to use novel materials or introduce more variety, enabling a player to find a bat that appeals to him or her. In referring to the use of nanoparticles in bats Smith said, "some will be for hype and some will be for true scientific purposes. The consumer doesn't always know which is the case with the product they're buying."

According to Thomas, choosing a bat shouldn't be stressful. "There isn't one tell tale sign that if you are of a certain height you should use a certain bat." He said that players should consider the weight, length, and above all the feel of the bat in their hands.

Baseball fans often say that when a ball strikes a great player's bat it just sounds different. But some people find other ways to enjoy the interaction of a ball and a bat. Smith's interest in this topic is grounded in the science, not a great love of the sport. "I can watch a game, but I'm actually not a huge fan. I'm an experimentalist and the tests are just for me a gas. I love testing bats. Building cannons, watching things in high speed video. To me, life doesn't get much better than that."

 

Author Bio & Story Archive

Chris Gorski is the Senior Editor of Inside Science. Follow him on twitter at @c_gorski.