 
Pencils don't actually contain lead. The core is actually graphite, a crystallized form of carbon, that's mixed with clay and a little bit of water. Sometimes there's more clay, while other times there's more graphite. The graphite is ground down and mixed with powdered clay and water to make a thick paste. This paste is heated in a kiln to produce a strong material that's difficult to break, but which will write smoothly on paper. Cedar wood is often used to make pencils. The best trees are around 14 years-old. One such tree can make up to 300,000 pencils. Pencil manufacturing is done at factories that use an assembly line with mechanical saws, lacquer sprayers, and giant kilns. Here's how pencils are made: 
The wood for a pencil needs to be soft enough to sharpen, but not too soft or it will bend. To achieve this, the wood is cut into slats and placed in kiln to dry. This gives the wood a consistent size and moisture content.The slats are then stained and waxed, and passed uder a cutting wheel that carves grooves, which will eventually jold the graphite cores. The grooves are filled with glue.  
The graphite mixture is extruded into cylindrical strips and baked in an oven at about 800°C.
A machine puts the graphite into the wood slat with the glue, flips that wood slat over, and then stacks another piece of wood on top, like a sandwich.
The wood 'sandwich' is then queezed with over 2,000 pounds of pressure and given about an hour for the glue to dry. A fast-spinning cutter is used to shape the pencils into hexagonal cylinders, and the individual pencils are cut out of the sandwich. Any pencils with defects are discarded.The pencils are next sprayed with coloured lacquer, anywhere from four to ten coats depending on the desired quality and colour. 
Rubber and aluminum are also needed. The rubber is used to make the erasers, while the aluminum creates the ferrules that hold the erasers in place. At this stage, the metal ferrule and rubber eraser are added to the top. Often pencils will have an image or text printed on the barrel, even it's just the "HB" or "2" used for grading graphite, the name of the company that made the pencils, or some other fun design. Find out about the grading system for pencils here. |