I’ve talked a bit before about machining equipment and how we work with a lot of machine shops at my work. The nice thing about this is I often feel like I have a pretty good handle on the whole CNC machining terminology, working with enough of it day in and day out. As always, just when I feel like I understand a section of the industrial market, I come across something to prove that I don’t know what I thought I knew. In this case it has to do with both vertical machining centers and 5 axis CNC machines — both coming from the same client.
So, in less than 20 minutes (since I wasted some time on that intro paragraph) here’s what I’ve learned about these two concepts that, it turns out, are thoroughly known by anyone in the machining industry.
Vertical Machining Center
The client I was talking to was using the term vertical machining center a lot. I did some research online and learned that the term is not just very common, but it’s also a significantly searched term on Google. The problem I had was literally no site I could find explained what the heck a vertical machining center actually was. I found the same issue with 5 axis CNC machining, it’s worth noting. Everyone brags about their 5 axis CNC machining capabilities, but they all assume that if you’re looking for it you already know what it is.
But starting with vertical machining centers. Despite that fact that they called “machining centers” — something that makes me think of large buildings filled with CNC machines — it’s actually a single CNC machine. Also, the machine does not necessarily have a vertical orientation.
Instead the vertical machining center just refers to a CNC machine in which the cutting element — the thing that actually cuts the metal — is aligned vertically. Think of a drill press — the drill bit is oriented up and down, vertically. Apparently there are also machining centers (which again are just a single CNC machine) in which the cutting element is aligned horizontally. Unsurprisingly these are horizontal machining centers.
I never did get a good answer on why they’re called machining centers, rather than just machines — which is after all what they are.
5 Axis CNC Machines
So I’ve been hearing the term 5 axis CNC machine forever, and in fact most vertical machining centers are in fact 5 axis CNC machines. My issue with this terms is what the heck are your 4th and 5th axis? I mean, 3 axis CNC machines (which are also a thing) I can get. You’re able to move up and down, forward and backward, and side to side.
Right there you have it, all three dimensions. You don’t get more than that without making up things, like time as the 4th dimension, for example. So how the heck can you have more than those 3 axis? You can move everywhere with just those three.
Well, the explanation actually makes a lot of sense. In a 5 axis CNC machine the surface that holds the item being cut can move along the normal X, Y and Z axis (side to side, forward and back, up and down) but in addition to that it can also rotate along the X and Y axis. Once you picture that in your mind you can see how it does indeed allow for additional motion that can’t be replicated with just 3 axis.
Apparently the reason this is desirable is that it lets your vertical machining center machine more complex parts without having to stop and change the setup of the vise that’s holding the metal being machined. This is important not just because it means you get the job done faster, but because it adds precision to the machining job. If you stop and manually adjust the vises and actually reset the object being machined, you’re inevitably going to get it positioned slightly differently — it’s just not possible to set it up perfectly. So the 5 axis CNC machine lets everything cut from one single setup, giving a lot more precision.
And darn it all — I went over 20 minutes. I need to use fewer words.