How LEGO bricks are made

LEGO makes roughly 36 billion bricks a year, or about 1140 pieces every second.

stations: 6
things upstream: 25
raw sources: 9
steps from the ground: 7

The short version

LEGO bricks are made of ABS plastic. Colored granules are dried and melted, then injected into steel molds under very high pressure. The mold cools the plastic into a finished brick in seconds, and the brick drops out. Bricks are checked against a standard and packed into boxes for sets.

Color and dry the granules

ABS granules are blended with color pigment and dried. Each color is stored in its own silo so that shades never mix.

Goes in
ABS plastic Pigment
Melt it in the barrel

A screw inside a heated barrel melts the granules. It pushes the soft plastic forward toward the mold.
Inject it into a steel mold

The molten plastic is forced into a cavity machined to precise dimensions. The tight fit of a brick on its neighbors depends on the mold being exact.
Cool and eject the bricks

Water channels in the mold chill the plastic until it holds its shape. The mold opens and the finished bricks drop into a bin.
Check a sample

Bricks are tested for fit and clutch, which is how firmly they snap together and come apart. Any that fail are discarded and ground up for reuse.
Pack into set boxes

Machines count out the right bricks for each set and seal them in bags. The bags go into boxes with instructions.

End of the lineLEGO brick

Worth repeating

The machines that make Lego bricks hold tolerances as small as 10 micrometers.
By July 2015, 600 billion LEGO parts had been produced.
LEGO began making interlocking bricks in 1949, inspired by the self-locking bricks invented by English toymaker Hilary Page in 1939.