I've been noticing something over the last couple of years that got me thinking.More and more cylinder drawings coming through seem to call for 20MnV6 instead of the usual CK45. It isn't every project, but it's definitely happening more often than it used to.
Years ago, CK45 was pretty much the default choice for chrome plated rods. It's easy to source, machines well and has proven itself for a long time.So I'm curious what's driving the change.From what I've seen, it usually comes down to the application rather than simply choosing a "better" material.
Machines like large excavators, mining equipment and heavy loaders are working under much tougher conditions than they were twenty years ago. Higher hydraulic pressures, heavier attachments and longer operating hours all put more stress on the cylinder rod.
In those situations, 20MnV6 seems to make sense because of its higher strength and better resistance to repeated loading. At least that's been our experience.
That doesn't mean CK45 is suddenly outdated. Far from it.For plenty of standard cylinders, CK45 still does exactly what it's supposed to do, and there's no reason to spend more money if the application doesn't require it.I guess that's really the point.Material selection isn't about choosing the strongest steel available. It's about choosing the steel that fits the job.I'd be interested to hear what others are seeing.
Are your customers asking for 20MnV6 more often these days, or is CK45 still the material you see most?
We've been comparing the two materials in a bit more detail recently, looking at fatigue performance, machining and why certain European OEMs seem to be moving in this direction. Happy to share what we've found if anyone is interested.