The Ball Game

How a tennis ball is made.

There’s nothing like opening up a new can of tennis balls. The “pssshhht” as you pop the top, that new tennis ball smell, the distinct texture of the felt, the firm feel of the pressurized ball — then the tingle of excitement you feel as you drop the ball for that first hit.

How does all that get packed into those clear plastic cans? We went to the Penn factory in Phoenix to find out. Penn Racquet Sports manufactures 330,000 tennis balls a day. Here’s how they do it.

Step One

A top-grade natural rubber compound is mixed with 11 chemical ingredients.

Step Two

The mixture is perfectly smoothed out and extruded into pellets, each made precisely the same weight.

Step Three

The pellets are placed into a mold and formed into hemispheres.

Step Four

The edges are then buffed to extremely fine tolerances, then coated with a natural rubber adhesive.

Step Five

The halves are then placed in another mold for the second cure process, which fuses them into complete ball centers.

Step Six

During this process, a controlled degree of pressure (equivalent to twice the Earth’s atmosphere) is sealed into the centers. These pressurized ball centers are then abraded to better retain the adhesive and grip the cover when applied.

Step Seven

The cover for Penn balls is made of a blend of nylon, wool, and cotton felt, pre-tensioned to prevent shrinkage in production as well as in play.

Step Eight

The process of bonding the covers involves a unique mechanical process exclusive to Penn.

Step Nine

A third cure assures a solid bond between cover and center.

Step Ten

The balls are steam-fluffed to raise the nap, thus ensuring that they react better to the court surface and racquet.

End of the Line

Once the balls are made, cans are filled, labelled, boxed and shipped.

The finished balls are tested for uniformity of bounce and deformation, durability of the cover, as well as flight, impact, wear and resistance characteristics to ensure that every ball precisely meets the International Tennis Federation’s specifications in the Rules of Tennis.

See all articles by Crawford Lindsey

About the Author

Crawford Lindsey is co-author of The Physics and Technology of Tennis and Technical Tennis