.. , because theyve drilled out the heart of it. You may remember the time when [pro player] Graig Nettles put a bunch of rubber “superballs” inside his bat, and the bat broke, and all the balls spilled out. Nettles attributes the persistence of corking more to head games between the players than to any advantage a corked bat might have. Players have also been known to rub their bats with ham bones or glass bottles, a process called “boning,” in an attempt to harden the bat. However, this practice doesn’t seem to produce any benefit beyond the psychological either. In early days, some hitters would illegally hammer nails into their bats so that the ball would strike “iron.” Even if the bat could be made harder, it would only diminish hitting. Solid wood bats “give” very little in the impact area, and thus they store very little energy.
What little they do store, they give back [to the ball] very efficiently. On the other hand, the ball distorts a lot under impact, and is relatively inefficient in giving the energy back. So a harder bat just results in more deformation of the ball, and a lesser hit. The question that come to us next was, but what about a metal bat? The most stunning change in baseball bats in the past thirty years started in the 1970s, when bats made from tubes of aluminum began to appear. These tubes are machined to vary the wall thickness and the diameter, and produce bats that are light, strong, and hollow, as opposed to the solid wood.
At first, the aluminum bat was just a metal copy of a wooden bat. They were just more durable, so they were cheaper to use. But manufacturers and players soon discovered that there were other differences as well. Aluminum bats are quite different than wooden ones. They’re much lighter, more than five ounces.
The barrels are bigger, and because they are lighter they can be swung faster than a wooden bat. In addition, the hardness and resilience of aluminum can result in much greater speeds when the ball comes off the bat. Major League Baseball has required that its players use wooden bats, but the aluminum bat has come to dominate the lower levels of baseball, from Little League to American Legion to the college game. The most significant difference between wooden and aluminum bats is that with an aluminum bat, a phenomenon occurs called the ‘trampoline effect.’ The walls of the bat are thin enough that they deform, or flex when the ball hits the bat. Some of the energy (of the collision) is transferred into the bat instead of the ball.
That energy is almost totally elastic; it is given back, or bounces back, almost 100 percent. The energy absorbed when the ball is deformed is almost 75 percent lost to heat, and thus wasted as far as propelling the ball. Because of this trampoline effect, you can hit the ball somewhat faster, and somewhat farther. In fact, when the NCAA approved the use of aluminum bats in 1974, H&B started comparing statistics and found that the team batting averages went up about twenty points, and the home-run production about doubled. The primary reason that wooden bats are required in the pros is due to this performance difference.
The pro leagues want to protect their historical records, and they want the performance of the game to be the result of human ability, rather than the technology of the bats. Ever-increasing performance of metal bats has begun to affect the game at the college level and below. Aluminum bat makers have been exploring stronger and lighter metal alloys. The results include ever-lighter bats with thinner walls, and consequently higher bat speeds and even greater trampoline effects. A ball hit by these bats travels farther and faster. In addition, H&B has already made a bat called the AirAttack in which a polyurethane bladder is inserted into the center hollow, then filled with pressurized nitrogen gas.
The gas pressure in the bladder supports bat walls, pushing them out after they are deformed under impact. This support allows a much thinner wall and a greater trampoline effect. H&B has a softball bat called the Inertia, in which the interior of the bat contains a rolled-up steel spring that does the same thing. Batting averages and home-run production have gone up consistently at the college level as these advances have appeared. Titanium was used briefly, but it was quickly prohibited because that metal’s combination of high strength, light weight, and elasticity was clearly going to result in shattering all hitting records in all phases of the game. You could actually grab the barrel of the bat in your hands and squeeze, and you could feel the bat give.
The trampoline effect was enormous, and though titanium was banned, Louisville Slugger learned a lot about how to make aluminum bats achieve the same effect. Recently, a heated debate has broken out over the widespread use of aluminum bats in college leagues. Many in baseball fear that modern technology is creating a “superbat,” which will irrevocably alter the game and endanger players. Indeed, the rules committees are diligently looking at the performance of bats, and they have already put some limits on performance; they may well add more. They are not only concerned about the integrity of the game, the balance between offense and defense, but they are also concerned about safety.
The NCAA rules committee has decreed that many modern metal bats are dangerous to players and disruptive to the game. The high speed of the ball coming off the these metal bats has put pitchers in danger, as a line drive hit at them may be traveling too fast for them to get out of the way. And the energy of a hit ball increases as the square of the velocity, so a fast hit can do more damage. As a result, the NCAA has ordered recently that bat manufacturers alter their designs to make bats heavier, with a smaller barrel. And baseball organizations from college to Little League are considering a return to a “wooden bats only” policy, though the expense of wooden bats may make such a move unfeasible.