When you buy a dividend stock you expect that the dividend will be paid reliably quarter after quarter. But that's not always the case, as we've seen with many energy stocks in the past year, who have cut or eliminated dividends altogether. 

But one company has a business that's about as bulletproof as they get. 3M Co (NYSE:MMM) is an industrial conglomerate with exposure to nearly every end market in nearly every country around the world. That diversity, and the cash generated from its innovative products, make its dividend one for the ages. 

Multiple innovations went into products like Post-it Flags. Image: The Motley Fool

How to build an unsinkable business
When you think of 3M, you probably think of the Post-it Note or Scotch Tape. These are the two of the most iconic products 3M has made, but they're actually from its smallest business. The Consumer Division accounted for just 14% of sales and operating income in the first quarter of 2015.  

Industrial, safety and graphics, healthcare, and electronics and energy businesses are all larger and they show the breadth of products 3M makes. The screen you're reading this article on probably has at least one 3M product, the building you may be in was built using 3M components, and the electronics that's all around you is probably tied together using 3M connectors and ties.

What makes 3M so large, and so indispensable, is that it makes components that are critical to making the products you use work but doesn't make many of the end products themselves. They're primarily a business to business sales company. This is an attractive position to be in today because a lot of the disruptive innovation being developed by start-ups are in technology. Few competitors are creating the next great sandpaper, which reduces 3M's competition.

Generating cash hand over fist
This strong competitive position with diverse end customers has created a cash flow machine -- and that's what drives dividends. Just look at 3M's free cash flow trajectory over the last two and a half decades and the steady dividend increases. And the payout ratio is very manageable below 50%.

MMM Free Cash Flow (TTM) Chart

MMM Free Cash Flow (TTM) data by YCharts

The history of strong dividends goes back a lot farther than this chart does. 3M's recently announced $1.025 per share dividend is in the 98th straight year of dividends and in the 57th straight year of annual payout increases. Even history is on the side of this dividend stock.

Sleep tight with 3M's dividend
If you're looking for a dividend stock to buy and hold for years, or decades, 3M should be at the top of your list. It's a business that's well established, diverse, and it spits off tons of cash flow year after year. Those are three factors all dividend investors should love and I think they'll continue long into the future. With a current yield of over 2.5% and a high likelihood that increases can be expected for years to come, 3M is the ideal choice for dividend focused investors.