LEGO bricks are manufactured with such extreme precision that only 18 out of every million fail quality checks.

The LEGO Group utilizes high-precision injection molding machines that exert pressures between 25 and 150 tons to shape plastic into bricks. The molds themselves are crafted from high-grade steel and are engineered with a tolerance of just 2 micrometers (0.002 mm). This level of accuracy is essential for the 'clutch power' that allows bricks to stay together while remaining easy for a child to pull apart.This manufacturing standard has remained remarkably consistent since the current brick design was patented on January 28, 1958. Because the molds are so precise, the company reports that only about 18 pieces per million fail to meet their rigorous quality standards. Most of these rejected pieces are recycled back into the production process to minimize waste.The primary material used is Acrylonitrile Butadiene Styrene (ABS), a thermoplastic polymer known for its strength and rigidity. During production, the plastic is heated to 232 degrees Celsius (450 degrees Fahrenheit) before being injected into the molds. This controlled environment ensures that every stud and tube aligns perfectly across billions of units produced at factories in Denmark, Mexico, Hungary, and China.The consistency of these measurements is verified by automated sensors and human inspectors throughout the 24-hour production cycle. This dedication to precision is why LEGO has become the world's largest toy company by revenue. It ensures that a collection can span generations without losing compatibility or structural integrity.