Tennis balls and tennis racquets without question are the most important pieces of tennis equipment, it`s impossible to vision one without the other.Tennis balls have changed over the years and a lot of research has gone into producing the perfect balls for all surfaces.
Different surfaces require different ball type, and ITF(International Tennis Federation)has been testing different Tennis balls since 2001.
The ITF responsibilities among other things is to enforce rules in the game of tennis, regulating competitions and promoting the game of tennis.ITF shares this responsibility with WTA(Women`s Tennis Association) and ATP( Association of Tennis Professionals).
Although the process of manufacturing tennis balls has remained the same over the years, the inspection has evolved with changing times and technology.
In the past, tennis balls were produced in Europe and the USA, but to take advantage of the lower production cost and cheap labor, the production is now in Asian countries.
Most major and popular sporting events involve the use of balls, Tennis, basketball, volleyball, football handball and the list goes on.Not as many sporting events are one kind of ball or the other not in use.Even in athletics you will find balls of a kind in hammer or shot put.It`s only in few sporting events like skiing where balls are not involved.
Tennis Balls Approval Tests
If a Tennis ball fails a brand test, be it size or mass, then ITF will not grant approval for such ball to be used.Manufacturers can re-apply by having another sample tested.For ITF ball testing approval, all balls must pass the specified tests.
To be sure temperatures do not affect tennis balls, all balls are acclimatized for a 24 hour period in temperatures of 20° AND AT 60+/- relative humidity before testing.
Temperatures and humidity can affect tennis balls properties.High humidity can increase the mass of the ball, increased moisture to the ball felt and high temperatures can increase bound height.
All tennis balls to be tested are pre-compressed in a tennis compression machine.The machine pre-compresses each ball 3 times from 3 directions using pneumatic actuators.
Until the year 2000, tennis balls could weigh 56.7-58.5 Grams but this has since changed to 56.0-59.4 Grams.
Tennis balls must have a certain weight, size and deformation.As simple a task as it may look, accurate ball diameter must always be reached.
To check and control the size, a tennis ball size is determined by passing it through two ring gauges to check for concentricity.There is no room for error and the ring gauges are calibrated to just0.0064 cm, (+/-) .The two rings gauges are calibrated to accept ball diameter of 6.54cm-6.86cm.This specification has not changed in a long time.
Each tennis ball bounces differently on impact with a tennis racquet or the surface where one is playing, this is known as deformation.
The machine used to test ball deformation in the past and present is known as Stevens machine, but as technology improves, there are now quicker ways to test the balls using automated testing devices controlled by a computer.
Stevens machine applies a known force to a tennis ball placed between two plates, everything is done manually and time-consuming.
Automated machines have an advantage over Stevens machine as there is less possibility of operator error not to mention speed.
Ball deformation has stayed the same since it was introduced in two parts, forward deformation in the 1930s. and the return deformation in 1967.
There is a rule specifying how a tennis ball should bounce, introduced in 1925, the rule has stayed the same to date.
Testing ball bounce is done by dropping a ball from 254cm and measuring the rebound, which should then be 135-147 cm.This will differ depending on the altitude and should be 122-135 cm at high altitude.
ITF laboratories use a vacuum pipe that holds the ball at the right height before releasing to a smooth granite block where the ball bounces to a video camera and light source. Each bounce is recorded and the rebound height measured from the shadow of the ball that is cast against a scale.
This is all done with software that analyses the video of the bounce in real time and calculates the height using the contrast between dark (the ball) and light (the background) over a series of frames either side of the peak.
Tennis ball durability is important and all balls are measured for size, rebound, and deformation.Lab equipment is used to simulate the effects of nine real games play.
Durability test begins in the wear rig, which contains an air cannon that fires the balls onto a rigid surface at approximately 90º.
The impact speed of the ball is (144 km/h), each ball is subjected to 20 impacts. The outer surface (cloth) of the ball is then worn by putting two balls at a time in an abrasion box for 2 minutes. The abrasion box is lined with rough emery paper and has three rotating wooden paddles that knock the balls around inside the box.
The effects of nine games of play (i.e. a typical ball change) were established by measuring new and used balls from tournaments played on a variety of surfaces.
In general, balls softer (deformation increases) and weigh less after they have been used. However, the mass of a ball used on clay often does not change because particles of clay stick to the cloth of the ball.
In the rules of professional tennis tournaments, it specifies that a tennis ball has to be yellow in color but you can find different colors of tennis balls should you wish to have them in other colors.
Read more from ITF pdf file to learn more about different colors and color rules in tennis balls.You can also watch the video below to understand more about different colors and sizes in tennis balls.
Hope l have helped you with questions you might have had about tennis balls, if you have any questions, just leave me a message below and l will sure get back to you.All tennis balls can be found at Amazon.com or other online stores.