3D Printing or CNC?
3D Printing and CNC machines both create three-dimensional objects, but which one should you choose? The answer may not be as simple as you expect, especially if you have used a CNC machine for decades. If you move a little bit outside your comfort zone, you could discover the best tool for the job depending on what you need. When you’re evaluating, try not less think of it as 3D Printing or CNC but rather, work backward from your end goal and consider three crucial factors: accuracy, material needs, and time.
No matter the technology, 3D printing is usually accurate to around 0.005” depending on the geometry of the object. There are some nuances to this depending on the orientation of the part, material, technology, blah blah blah, and the technology is always improving, BUT as a general rule of thumb, 0.005” is a good number.
If you need accuracy on your part tighter than 0.005”, CNC machining might be the way to go. Either that, or you would need to 3D print the model and then put the part on a CNC machine to finish it. That is more work, and nobody typically wants to do an extra step if they don’t have to.
BUT there is a workaround that users typically learn quickly if they have a 3D printer. If you change the dimensions on your 3D model a tiny bit, you might get the actual dimensions you want. This is kind of a distraction from the main purpose of this blog, so I will follow up with a second one and link to it here.
If your part needs to be made out of a very specific alloy or polymer, chances are you could have a hard time 3D printing it, or finding someone to 3D print it for you. That being said 3D printing offers a lot of materials to choose from – way more than a few years ago. If you can be a bit flexible on what your part is made of, 3D printing has a good shot. We wrote up some guides on 3D printing materials that you can check out here: 3D Printing Materials Cheat Sheet
Time is the biggest factor in the 3D printing or CNC debate, and it might also be the most ignored. This is typically the place where our customers who implement 3D printing see the biggest returns. Imagine you are running six-figure CNC machines 24/7 to crank out parts for your product. If you take one of them off-line to make a tool or fixture, that time is very expensive. Allowing an engineer to essentially press a button and get a 3D model back quickly has repeatedly proven to be valuable to operations everywhere. The 3D printing or CNC workflow is drawn out below to make the benefit a bit more obvious.
3D printing and CNC machining both have their place in today’s manufacturing environment. Which one you should choose depends on your specific needs, but can be boiled down to Material, Accuracy, and Time.