What is CNC milling?
Although methods of material removal differ, first, CNC drilling and milling machines and CNC lathes each remove material to produce a part. A machining center usually combines two methods and multiple tools in one machine. All of these feature multi-axial motion that guides the cutting tool around and through the workpiece to create the exact shape required.
The basic difference between the two methods is that a milling machine uses a rotating tool to cut on the workpiece, while a lathe is a rotating workpiece and the meshing is done by the tool.
How does CNC milling work?
Before the introduction of computer digital control (CNC), milling machines and lathes were manually operated. As the name suggests, CNC automates this process, making it more accurate, reliable and fast.
Now, a trained operator codes the G code (which stands for geometric code) into the machine, usually through software. These control milling machines, each of which controls stroke and speed so that it can drill, cut and shape material to fit a given size.
There are many different types of CNC milling machines. The most common are 3-axis machine tools, which move along the X, Y, and Z axes to provide tools for 3-D manufacturing. A three-axis machine can produce more complex features by rotating and resetting the workpiece to allow entry from multiple angles.
On a five-axis machine tool, this capability is optimized by adding motion in two directions, rotation around the X and Y axes. It is ideal for the production of complex and sophisticated parts. However, the downside is that using this technique can break your budget because complexity increases costs. Believe it or not, with five axes of motion, you can define any three-dimensional geometry. However, it is not practical to hold the workpiece and rotate it freely in all directions. This will be a machine with 6, 7 or even 12 axes. However, unless you need extremely complex parts, you are highly unlikely to need such a machine - because the investment is huge, as is the size of the machine!
What is the next step in NC machining?
As you can see, the development of more and more complex CNC milling machines, which are larger and more expensive to buy, require more and more expertise to operate, which takes a lot of time. Even if you outsource CNC processing, the cost of this complexity is higher, because specialist manufacturers have to recoup their investment. If you have an extremely complex part that requires incredible precision and requires a lot of use, you may be able to justify the investment. For most jobs, 3 - or at most 5 - axis machining is more than adequate.
After all, there is always more than one way to solve a problem -- often, for example, it is much better and cheaper to design two or more less complex parts and then bolt, weld or connect them as part of a secondary assembly process than to try to craft an extremely complex single part.
So why is there so much focus on developing new expensive and huge machines that are generating less and less profit? It's kind of like the Microsoft office. Most of us use Word, but in reality we probably only use 20% of what it has to offer. Yet Microsoft keeps adding new features, most of which we may never need, use or even know about.
Instead of making smaller and smaller incremental improvements to the process, we think we should improve the process itself. This is where we can make real gains.
process automation
Let's go back to the beginning and examine the process of making a part.
It all starts with the designer designing the required parts or components on their CAD system. Typically, an experienced person programs the G code for computer aided Manufacturing (CAM).
But once the design is in place, why add another step? The good news is that there are many CAD packages you can use to convert your CAD to G code -- but we need to take a step back.
Once you have designed your part, how do you know it can be manufactured using CNC machining to your desired tolerances? Your CAD should be the digital wire that connects everything with little or no human intervention.
After all, with Industry 4.0, we are all supposed to live in a connected world. Much of the work of CNC machining still relies on experienced machinists. When you send in your design, usually one person checks to see if it can be made using a known process. If not, you need to be told so you can redesign or optimize the design.
At Protolabs, we have automated this process. Once you have sent your CAD data, our software will check its feasibility and generate a quote. If suggested changes are necessary, they will be shown to your CAD in a feasibility report automatically generated by the software. Once you agree to design and manufacture, our software creates the code required for fabrication as specified in the quotation sheet.
Faster and more cost effective
This makes the process faster and more cost effective, which can make a real difference for small to medium-sized jobs or for prototyping and testing new parts.
Thanks to automation, the service is the same for everyone, no matter the size of the project. It is understandable that traditional engineering firms will prioritise projects that will allow them to make more money -- whether because of the size of the work or the complexity of the parts needed -- depending, of course, on their capabilities.
Automation of processes levels the playing field. So, for prototyping or requiring a small or medium number of parts, you can still benefit from the same speed and quality of service.
Because all this information is generated and collected from the beginning, we can cut and ship custom CNC milled plastic and metal parts in as little as 24 hours. If you're not in too much of a hurry, you can opt for a later delivery date and lower your costs - so you can even set the terms yourself.
The process starts with your CAD, which means that after you have designed your part, we have a digital line that we can use throughout the CNC machining process - from your computer to delivery.
Automation is not just a matter of CNC milling and turning. It covers everything from the design onwards. This is the future of CNC milling. This is real Industry 4.0 action.
