Let’s talk about the elephant in the room: chrome ways. It might not be a pleasant discussion. In fact, a few of you might become upset. That’s especially true of the older machinists, the ones who were turning cranks and picking up edges before many of us were born. Chances are good they were doing so on a well-known brand of knee mill. I’m not naming names, but those machines are no longer made by the same company. And from what I heard, they’re not even made in the same country. Times change.
What hasn’t changed is a big selling feature of those old machines, something I hear about fairly often. Chrome ways. Are they worth it? Kent USA doesn’t think so. That’s why all of our KTM-series manual knee mills have hardened and ground ways, not chrome. It’s the same with practically all of our competitors. Google it if you don’t believe me. But that once iconic brand? Yep, chrome ways. They charge a pretty penny for it, too.
No Big Deal
I get the reasoning. Chrome ways are hard, up to 72 Rc or so, maybe 25 points higher than the gray cast iron without heat treat found in most machine tools around 30 rc. And harder surfaces wear better, right? It’s pretty easy to argue that chrome ways are going to last a long time. But here’s the thing. Unless you forget to fill the way oil, all machine tool surfaces ride on a thin layer of oil. That’s how hydrostatic ways work. So chrome? It will certainly help the wear properties of softer metals, especially where abrasion might be a concern. A hardened and ground machine tool way? Not so much.
After the Party
Here’s the other thing. When the milling machine grows tired and it’s time for a rebuild, what then? Any reputable machine tool rebuilder can hand-scrape a milling machine with hardened and ground ways. With chrome ways, the chrome has to be removed first. I’m no scraper, but I’m told that can’t be done by hand. So in addition to the big cash outlay up front for the chrome ways, you’re now going to pay dearly to have it removed. Just saying.
Gimme’ One Reason
You might be thinking that I’m just making excuses for my equipment. Why would I do that? Chrome ways aren’t rocket science. Granted, the chrome has to be applied properly. It’s the Goldilocks thing—not too much, not too little, and it had better be dead even across the entire surface. But does anyone think that Kent USA, with 40 years of experience and many thousands of machine tools under its belt, would avoid using chrome ways if they made sense?
We’d rather spend money on what’s important, so you have more money for tooling and accessories. On the things that make the job easier. Things like super-precision ABEC-7 spindle bearings. A variable speed AC drive motor with digital RPM display and analog load meter. Precision ground leadscrews with a backlash-compensating nut. Oh, and an automatic lubrication system, in case you’re one of those people who forgets to fill the way oil.