2.3.1 The manufacture of tennis racquets
In this activity you are asked questions on the following video, which shows one method of manufacturing modern composite tennis racquets.
Activity 3 Tennis racquet
Timing: Allow about 10 minutes
Consider the following questions as you watch the video and note down your answers.
- a.How many layers of CFRP are added to the frame at the start?
- b.How and why do they keep the core hollow during the heating process?
- c.What material is added to the inside of the frame, and why?
Download this video clip.Video player: t271_2018j_openlearn_vwr046-640x480.mp4


Transcript
[MUSIC PLAYING]
NARRATOR
The pros have them, and you want them-- perfect shots hit with confidence and timing. How much does the racket have to do with it? Well, certainly, a combination of power, balance, and feel must be made available to all players at all levels.
The life of a modern high-tech tennis racket begins as strands of carbon, Kevlar, and fibreglass that are coated with resin-- these fibres are wound onto a spinning drum that's been covered with a paper sheet. This will form the basic material of carbon fibre tennis rackets. Layers of carbon fibre are cut into shapes and wrapped around each other to form a laminate stack of between seven and twelve layers. As the pliable material begins to take the form of a basic tennis racket, additional pieces and layers of carbon fibre are added to specific areas to provide strength.
The racket is soft at this stage and is placed into a mould that will determine the size and shape of the final product. It passes through a heating process to cure and harden the carbon fibre, while pressurised air is blown into the centre of the frame to retain a hollow core. Each frame spends about 20 minutes in the mould at a high temperature until the material is fully cured.
The frame is very rough as it's removed from the mould and passes through a series of sanding and finishing processes to create a polished, smooth surface. Filling the hollow core with foam adds strength and stability to the finished product. A special collar is used to ensure accuracy and precision while drilling the string holes.
The frame moves through the final finishing stage before paint is applied. Prior to and after each coat is applied, the frame's surface is masked to protect the painted section from the next layer of colour. In the painting process, layers of glossy and matte paint dramatically enhance the appearance. The result is a multi-colour finish, complete with decals that enhance and highlight the overall frame technology.
Today's rackets not only look good and perform well, but also provide every player with the equipment necessary to maximise their game. Professional or amateur, recreational or beginner, the world of these high-tech tennis rackets is available to everyone, whether you're playing for fun or playing for a million dollars in prize money.
Interactive feature not available in single page view (see it in standard view).
Answer
- a.Between 7 and 12 layers of CFRP are added to manufacture the frame.
- b.Pressurised air is pumped into the frame, to ensure space is available for it to be filled with a suitable material.
- c.Foam is pumped into the frame to add strength and stability to the finished product.