Tennis is a sport that is played with a racquet and can either be played individually in a singles match or between two teams that will both be made up of two players (doubles).
A racquet that is made that is strung with cord is used to strike a hollow rubber ball over a net into the opponent’s court, with the objective being to strike the ball in a way that prevents the opponent from getting a good return. If they fail to return, their opponent will score or gain a point.
But how is the hollow rubber ball made? It is not as easy as it seems and involves a strenuous eleven step method. This method is detailed below.
- The first step is making the hollow shells; this process is started with a blend of natural and synthetic rubber. There are special powders and chemicals mixed into the rubber.
- Machines then knead the mixture to make it softer and ensure it has specific properties including colour and strength.
- They then heat the compound to make pellets that all have the same weight. Once they are cooled down they are placed into a mould. With extreme pressure a hydraulic press presses the pellets into half shells.
- Once they cool the half shells are removed from the mould.
- Next the core is formed. The core is created with a number of machines and a number of workers.
- The first machine takes up the job of removing excessive rubber which may have leaked out in the mould and adhered to the sides of the half shells.
- The next buffs the edges of the half shells to allow a good bond to be formed when two of them are glued together.
- This same machine then puts the half shells on a conveyor where the rims are coated with a rubber adhesive.
- Workers load the half-shells into a press machine with two mould trays -- one for the bottom half-shell and one for the top. Compressed air is then placed into the cores as both the trays come together, fusing the shells to create the core.
- Now the core needs to be covered. The process of cutting out and attaching the cover requires a many sets of hands also and multiple machines.
- Machines stamp out pieces that are shaped like dog bones that are called blanks and made of a blend of wool, nylon and felt. Whilst they are being made the cores are taken and bathed in rubber adhesive.
- Machines then also apply white rubber adhesive to the edges of the blanks, these ends up as the white seems that we see on a completed ball.
- A specially engineered machine precisely attaches the two dumbbell pieces to the core, one piece is centred and wrapped around the core and the second is wrapped 90 degrees to the first. Workers will then place the balls into a moulding press which heats, presses and cures the adhesive which provides it with a smooth appearance.
- Now the ball needs to be tested and packaged. During the press and curing process, the moulding press tightly compresses the felt.
- Sometimes a ridge is left on the ball. Workers put the balls in a steam machine where they are tumbled to lightly fluff up the felt, which also causes the ridge to disappear. The balls must pass a bounce or rebound test.
- When dropped from a height of 100 inches onto a flat, hard surface such as concrete, they must bounce between 53 and 58 inches.
- After passing all the quality control tests, print machines stamp logos on the balls and package them in pressurized cans.