So what's really new in the world of mining this quarter? Apparently not a whole lot.

Production is still somewhat constrained in markets like coal, and miners of other minerals like iron, bauxite, copper, and gold are looking to reinvest today's rich cash flow streams into new production projects over the next few years. By and large, this suggests that there's more room left to go in this cycle for the likes of machinery makers Joy Global (NASDAQ:JOYG) and Bucyrus (NASDAQ:BUCY).

In Bucyrus' case, revenue rose 34% this fourth quarter on very strong sales of aftermarket parts and services, and mid-teens growth in new machinery sales. Margins expanded again, operating income rose 58%, and earnings before interest, taxes, and depreciation/amortization (EBITDA) climbed 52%.

I'm not sure whether there's much to be made of the fact that Joy Global seemed to do better in terms of overall growth and growth in new machinery sales. After all, Bucyrus' backlog is still quite strong, and the company continues to rack up new machinery orders. It's also worth noting that new machinery sales are a bit of a mixed blessing -- they are generally worse for margins in the short run, though you obviously have to make new machinery sales someday if you want that stream of aftermarket business in the years to come.

And that stream of continuing business is an important consideration. This equipment typically has a useful life around 20 to 40 years, so each new shovel or dragline sold constitutes a pretty significant chunk of eventual aftermarket business.

Couple management's guidance with the commentary we're hearing from mining companies, and I don't think there's an imminent concern about the health of the equipment cycle. Even if coal companies like Peabody (NYSE:BTU) have cut back on production expectations for 2006, they're still looking to expand production capabilities over the next few years, and machinery will undoubtedly be a key part of those plans.

Mine our archives for more related Foolishness:

Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).