Bowling Ball Manufacturing Process
Although the steps in manufacturing bowling balls vary with each company, this article will give you a generalized overview of the process in bringing today’s bowling balls to life. The process begins with making the core of each given bowling ball. The core of a given bowling ball influences ball motion by virtue of core symmetry and track flare potential ratings.
Between the early 1800s and the early 1990s, most bowling balls
were made of three-piece construction. A small amount of dense material was poured into spherical core mold to create a pancake-like core. The remainder of the core mold was filled with a less-dense core material. Finally, the core was centered in a mold and a layer about 1 inch thick of coverstock material was poured around the core.
Today, the manufacturing process is far more sophisticated than years ago. The first step in the manufacturing process today is to design and make the core of given bowling balls.
For the particular model of ball being manufactured, a mold is formed to the core shape developed during the computerized design process. The appropriate material is poured into the core mold and allowed to harden. The solid core is then removed from its mold.
Finishing the core is the next step. For example, some ceramic cores are fired in a kiln. A compound core may be formed by inserting the first core into a second mold and pouring material of a different density around all or part of it. Many cores use multiple pieces and varying mass densities to create many options for drilling the ball by pro shop professionals.
Creating the shell of the ball, known commonly as the coverstock, is the next step in the manufacturing process. The finished core is placed inside a spherical mold called the coverstock mold. The core is attached to a pin that projects toward the ball center from the shell of the mold. The pin holds the core in the correct and intended position.
If the pin points toward the center of the mold, the core is said to be pin in. If it is tilted away from the center, the core is pin out and the final finishing process will denote the pin marking related to the ball center of gravity.
The coverstock material is poured into its mold, encasing the core, and is allowed to harden. The thickness of the coverstock may be as little as 1 inch or as much as 2 inches, depending on the design of the particular ball.
When the ball is removed from the coverstock mold, there is a hole where the core-holding pin was positioned. A plastic dowel is inserted into the hole and cemented in place. The pin is a different color than the coverstock. After the ball has been purchased, the pin will be used as a guide for positioning the finger holes to take advantage of the core design.
Fill material is added to the logo imprint that was molded into the ball. This may be the same color as the pin, or it may be a different color. The logo is typically located at the top of the ball above its center of gravity.
Next, the ball is finished to the proper size specification by turning it on a lathe and shaving off enough coverstock to achieve the right shape. It also can be done on a center-less grinder that scours the ball into the desired size and roundness.
Finally, the surface of the bowling ball
is finished to the desired texture. It is sanded to either a matte finish or to an appropriate degree of polish. This is indicated by the roughness of the sanding material varying from 240 - 4000 grit, depending on the desired finish in generating desired ball reaction capabilities.
The ball is boxed, labeled, inventoried, and then shipped to the United States Bowling Congress (USBC) for approval for use.
Every manufacturer is concerned about quality control. The USBC has a primary mission of standardizing the sport by developing equipment specifications. The current rules require a ball to have a diameter between 8.500-8.595 inches and to have a total weight of 16 lb or less.
No minimum weight is specified, and some balls weigh as little as 6 lb. In order to earn the USBC seal of approval, sample balls of each model must be sent to the ABC for testing and verification of meeting the official standards.
Some new rules were adopted by the USBC circa 1994. The USBC rules establish limits on the bowling ball's radius of gyration, which is the distance between the ball's rotational axis and its center of gravity. The rule limits this value to 2.430-2.800 inches. Other USBC specifications govern such technical characteristics as the ball's coefficient of restitution (a measure of the energy transferred from the ball to the pins), surface hardness, and hooking potential.
The entire process in manufacturing bowling balls in today’s industry is a sophisticated one and very competitive from a business standpoint. When you face the challenge in choosing your next bowling ball, it helps to consult with your pro shop professional and/or someone who knows your game well enough to help you round out your equipment arsenal.