Why can a ping-pong ball go into space but not be taken on an airplane?

A few days ago,
Chinese astronauts in orbit actually played table tennis in the space station!

Image source: CCTV News Weibo

How come a ping-pong ball, which can’t even be taken on an airplane, can go into space?

It turns out that the original material used to make table tennis balls, celluloid, is a flammable and explosive aviation contraband. Its ignition point is 180℃, and it only takes a few seconds from ignition to fierce combustion. But now, table tennis balls made of new materials are environmentally friendly and safe, so they can be safely put into space! Speaking of this, today we will take a look at how various balls are made.

Ping-pong Ball

Image source: pixabay

Origin: Late 19th century, England

Diameter: 40mm (current standard)

Weight: 2.53-2.70g

Color: White/Orange

Raw materials:

Old - Nitrocellulose plastic (commonly known as celluloid, flammable)

New - Acetate (environmentally friendly and non-flammable)

Manufacturing process:

1. Raw material processing

Celluloid is a soft and elastic material, commonly known as "plastic", which has great tensile strength and is resistant to water, oil and acid, but is particularly flammable.

First, the raw material needs to be extruded into a thin sheet with a thickness of 0.8 mm, cut into a circle and polished smooth.

2. Gradual molding

The circular sheets are gradually extruded into a hemispherical shape through equipment, and the thickness is reduced from the original 0.8mm to 0.5mm. In this way, the hemisphere formed by two circular sheets can be spliced ​​into a complete ping-pong ball.

3. Bonding: Then put the two matching hemispheres together, put solvent in the joints, fuse and bond them together, and finally form a sphere.

4. Air drying and polishing Air drying is a long process that takes about sixty days. After air drying, add abrasive powder to the polishing machine and polish the ball until it becomes smooth.

5. Qualified inspection The inspection contents include: whether the sphere is damaged, whether the center of the sphere is deviated, the hardness, weight and roundness of the sphere.

6. Seal production

Qualified table tennis balls will be classified according to the star rating and printed with labels. Generally, three-star balls will be used as designated balls for professional competitions, while two-star and one-star balls are mostly used for practice.

Table tennis star classification standards:

Source: Compiled by the author

Badminton

Image source: pixabay

Shape: 16 feathers fixed on the ball base

size:

Height: 64-70mm

Ball holder diameter: 25-28mm

Feather tip diameter: 58-68mm

Weight: 4.74-5.50g

Raw materials:

Feathers: goose or duck feathers. Base: cork (high-end balls) or plastic (low-end balls).

Manufacturing process:
1. Wool making first requires the feathers to be preliminarily selected, washed, and degreased, and then made into wool pieces. They are then graded and sorted according to quality, and the next step of wool matching is carried out by mechanical operation.

2. Heading

Cut natural cork or synthetic material into the size of a ball head and make even holes on the neck in preparation for hair transplantation.

3. Assemble and implant the selected feathers into the pores of the ball head one by one, adjust the positions and glue them with glue, then hook the roots of each feather to fix the feathers.

4. After the test is passed, the badminton is printed and labeled, and it is freshly baked! Then it will be tested for its durability.

Soccer Ball

Image source: pixabay

Shape: sphere, usually composed of 32 pieces (12 pentagons and 20 hexagons)

Raw material: artificial leather

size:

No. 5 ball - standard ball for 11-a-side, diameter 20.8-21.4cm No. 4 ball - ball for 5-a-side or 7-a-side, diameter 19.0-20.4cm

Manufacturing process:
1. Making a ball bag: Punch and cut the artificial leather into the required pentagons and hexagons, and sew the leather pieces into a ball bag by hand.

2. Turn the bag over and embed an air bag: Turn the smooth side of the bag toward the outside and embed an air bag with good airtightness inside, so that the basic shape of a football is formed.

3. Cutting and printing the leather The leather wrapped around the outside of the football needs to be cut and processed, and the surface must be printed using printing technology.

4. Glue bonding

Finally, glue is sprayed on the surface of the formed sphere to tightly bond the sphere and the printed leather together, and then it is inflated and waits for inspection.

Nowadays, these balls are the most common things for us. However, these ordinary balls need to go through dozens of processes on the production line to be completed.
For balls used in large-scale competitions, the manufacturing process is even more demanding, and the error often has to be controlled within a very small range to satisfy the athletes' control over the feel of the ball.

Content reference & GIF source

[1] Facebook "Table Tennis Ball Manufacturing By Artengo" https://www.facebook.com/watch/?v=2717594728509484[2] Youtube "How Badminton Birdies Are Made" https://www.youtube.com/watch?v=XS7HLzQZFgk&t=185s[3] Facebook "How Footballs Are Made In Pakistan》https://www.facebook.com/watch/?v=432776891060366
Author: Wang Zhonghua, Ouyang Wei, Master students of School of Energy, Xiamen University Editor: Bai Yi Acknowledgements: Liu Haibin, Professor of School of Materials Science and Engineering, Shanghai University, provided scientific guidance for this article — END —
The copyright of the online pictures belongs to the original author. The article belongs to Shanghai Science and Technology Museum.