Comment c’est fait YouTube: La fabrication des crayons de plomb

The production process of a pencil starts with the main ingredient, graphite. This material, discovered in England in the mid-40s, gave birth to the pencil industry in 1795. A French chemist invented a new type of pencil lead made from graphite powder and baked clay. This allowed for the production of leads with different hardness levels.

To make the pencil casing, a type of wood is needed that is soft enough to be sharpened but hard enough not to bend under finger pressure. This German pencil factory uses Californian cedar wood, which arrives pre-cut into 18 by 7 centimeter boards with a thickness of 5 mm.

One by one, the boards pass under huge rollers that create grooves. These grooves will form the cavity that holds the pencil lead in the center. The next machine fills the grooves with a special slightly elastic glue. This cushions the lead and reduces the risk of breakage. Every second board is directed to another conveyor belt. The ones that remain on this production chain are sent to the machine that inserts the leads. The spacing of the leads corresponds to the grooves on the boards.

The leads are made of a mixture of graphite and baked clay at temperatures exceeding 800 degrees Celsius. The process is the same for colored pencils, except their lead is made of wax, clay, and pigments and is not baked. As for the boards that end up on the other conveyor belt, an automated arm flips them one by one. Each one then slides onto a glue applicator and ends up on one of the boards containing the leads. All these steps lead to the creation of what is essentially a lead sandwich.

A press compresses these sandwiches with a ton of pressure for an hour while the glue dries. Then it’s time to cut the sandwiches into pencils. A slicing machine shapes the hexagonal profile in two steps. First, the upper blade cuts three sides, then the lower blade cuts three more sides. The lower part is then baked and the pencils are detached.

A worker takes a sample from each batch coming off the production line and manually tests the lead’s quality by applying pressure until it breaks. For a pencil to pass the test, it must withstand at least 2 kg of pressure. Now it’s time to decorate the wood. One by one, the pencils go through a varnishing head that coats the wood with yellow paint. In this case, four coats of paint are needed to conceal the wood grain. A fifth varnishing head applies a black band, the company’s trademark. Then a sixth head applies a transparent varnish.

From the painting station, the pencils move to the stamping machine, which applies hot decals at an astonishing rate of 500 pencils per minute. The final stop is the machine that attaches the eraser. It runs along the top of the pencil, sliding in an aluminum ferrule and crimping it all together. European pencils also receive an imprint indicating the lead hardness.

After a layer of transparent sealant, the pencils are dipped multiple times in the first color, then once dry, in the second color. The final coat is an ultra-glossy varnish. The pencils are now ready to roll onto a sharpening drum to be sharpened. At the end of the line, they are ready to take all your notes. As decorative as they are useful, these contemporary pencils look great.


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YouTube a été créé en 2005 par 3 hommes : Chad Hurley, Steve Chen et Jawed Karim. Ils s'étaient rencontrés dans une autre entreprise où ils travaillaient tous les trois, à savoir PayPal. Ils trouvaient qu'ils avaient du mal à trouver des vidéos à regarder en ligne, et à partager les leurs.29 sept. 2019
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