Managing quality and variety at Lego

When I was a kid, I loved Legos. So I was, of course, pleased when my kids started playing with them. In the last year or so, my kids have outgrown them. And while having all the Legos put away makes it a little safer to walk barefoot across the family room, it does make me a litte sad. Which is why, I guess, I have a soft spot for stories about Legos.

Like, for example, a BBC story asking just how many Legos can you stack on top of each other (How tall can a Lego tower get?, Dec 3). Turns out, you can make a pretty tall tower.

Ian Johnston and the team do two more tests to be sure we hadn’t just happened upon the strongest Lego brick in existence. And in fact they were impressed at the consistency of Lego manufacture.

The average maximum force the bricks can stand is 4,240N. That’s equivalent to a mass of 432kg (950lbs). If you divide that by the mass of a single brick, which is 1.152g, then you get the grand total of bricks a single piece of Lego could support: 375,000.

So, 375,000 bricks towering 3.5km (2.17 miles) high is what it would take to break a Lego brick.

Here’s a graphic to help visualize 375,000 Lego bricks.

Let me point to the phrase “they were impressed at the consistency of Lego manufacture.” It might seem odd that Lego would aim for such consistency for a small part that is as likely to be chewed by the dog as built into a tower. But they make a lot of these things (36 billion “elements” a year according to the company) so conforming to set standards is important if various parts are going to work together. And that, according to NPR’s Planet Money (Why Legos Are So Expensive — And So Popular, Dec 13) is very much part of the company’s strategy.

“They pay attention to so much detail,” he said. “I never saw a Lego piece … that couldn’t go together with another one.”

Lego goes to great lengths to make its pieces really, really well, says David Robertson, who is working on a book about Lego.

Inside every Lego brick, there are three numbers, which identify exactly which mold the brick came from and what position it was in in that mold. That way, if there’s a bad brick somewhere, the company can go back and fix the mold.

Lego supports backward compatibility in a way that, say, Microsoft has never imagined.  But that also imposes some constraints on product design. Whenever Lego designs a new set (say for to coincide with the release of a new movie), they have to make sure that any new bits work with all of the old bits. One approach to this is to keep tight rein on what new pieces designers are allowed to add (What It Takes to Build a Lego Hobbit (and Gollum and More), Wall Street Journal, Dec 19). Many new pieces, especially, those for just one set, add complexity and costs.

Lego Chief Executive Jørgen Vig Knudstorp doesn’t want his designers reinventing the wheel every time they create a new collection. When he took the helm in 2004, designers would dream up ideas and get whatever materials they needed to turn the vision into reality. That business model was steering the family-owned company toward bankruptcy.

Seven years later, Lego posted nearly $1 billion in operating profit for 2011, meaning that the company kept about 30 cents of every dollar spent on its products.

To achieve that, complexity had to be reduced, so the number of bricks and other building materials was reduced to a collection of 2,700 pieces that today make up Lego’s “system of play.”