information:classification
Manufacturing

Since 1963, Lego pieces have been manufactured from ABS plastic. As of September 2008, Lego engineers use the NX CAD / CAM / CAE PLM software suite to model the elements. The software allows the parts to be optimised by way of mould flow and stress analysis. Prototype moulds are sometimes built before the design is committed to mass production. The ABS plastic is heated to 232 °C (450 °F) until it reaches a dough -like consistency. It is then injected into the moulds using forces of between 25 and 150 tonnes and takes approximately 15 seconds to cool. The moulds are permitted a tolerance of up to twenty micrometres to ensure the bricks remain connected. Human inspectors check the output of the moulds to eliminate significant variations in colour or thickness. According to the Lego Group, about eighteen bricks out of every million fail to meet the standard required.

Lego factories recycle all but about 1 percent of their plastic waste from the manufacturing process. If the plastic cannot be re-used in Lego bricks, it is processed and sold on to industries that can make use of it. Lego, in 2018, set a self-imposed 2030 deadline to find a more eco-friendly alternative to the ABS plastic.

Manufacturing of Lego bricks occurs at several locations around the world. Moulding is done in Billund, Denmark; Nyíregyháza, Hungary; Monterrey, Mexico; and most recently in Jiaxing, China. Brick decorations and packaging are done at plants in the former three countries and in Kladno in the Czech Republic. The Lego Group estimates that in five decades it has produced 400 billion Lego blocks. Annual production of the bricks averages approximately 36 billion, or about 1140 elements per second. According to an article in BusinessWeek in 2006, Lego could also be considered the world's number-one tyre manufacturer; the factory produces about 306 million small rubber tyres a year. The claim was reiterated in 2012.

In December 2012, the BBC 's More or Less radio program asked the Open University 's engineering department to determine "how many Lego bricks, stacked one on top of the other, it would take for the weight to destroy the bottom brick?" Using a hydraulic testing machine, members of the department determined the average maximum force a 2×2 Lego brick can stand is 4,240 newtons. Since an average 2×2 Lego brick has a mass of 1.152 grams (0.0406 oz), according to their calculations it would take a stack of 375,000 bricks to cause the bottom brick to collapse, which represents a stack 3,591 metres (11,781 ft) in height.

Private tests have shown several thousand assembly-disassembly cycles before the bricks begin to wear out, although Lego tests show fewer cycles.

In 2018, Lego announced that it will be using bio-derived polyethylene to make its botanical elements (parts such as leaves, bushes and trees). The New York Times reported the company's footprint that year was "about a million tons of carbon dioxide each year" and that it was investing about 1 billion kroner and hiring 100 people to work on changes. The paper reported that Lego's researchers "have already experimented with around 200 alternatives." In 2020, Lego announced that it would cease packaging its products in single-use plastic bags and would instead be using recyclable paper bags. In 2021, the company said it would aim to produce its bricks without using crude oil, by using recycled polyethylene terephthalate bottles, but in 2023 it reversed this decision, having found that this did not reduce its carbon dioxide emissions.