By Mike Dunlap
If you are familiar with the advantages of and possibilities that are opened up by CNC machining, you may have so far steered clear of the emerging trend for additive manufacturing. There is doubtlessly room for both technologies to coexist, even if there are also areas in which they are direct competitors.
No matter your experiences, expertise or allegiances, it makes sense to learn about what 3D printing brings to the table. To that end, here is a look at the main ways in which it differs from established CNC machining solutions in terms of how it works and what it can do.
Addition vs subtraction
The chief difference that distinguishes 3D printing from CNC machining is that rather than starting with a large piece of material and removing parts with tooling until the desired shape is achieved, the opposite approach is taken. A 3D printer starts from scratch with a blank printing bed, and the required material is delivered via extrusion through a heated nozzle.
This allows for individual components or entire products to be produced layer by layer, using only the required material. As such there can be far less material wasted in 3D printing, even if some parts may need supplementary supporting structures to be created as part of the printing process which are subsequently discarded.
Such a fundamental difference is the basis upon which the modern craze for additive manufacturing has gained and maintained momentum. Even so, the minimizing of waste alone is far from adequate to deliver a decisive victory.
CNC machining is undeniably versatile when it comes to the materials modern machines can be used to manipulate. From mills and lathes available from sites like Revelationmachinery.com that can be leveraged for working metals and woods to laser cutters that are compatible with everything from plastic to glass, contemporary equipment offers exceptional variety.
3D printing is also able to work with lots of different materials, although individual machines are usually more specialized in the material compatibility they offer. For example, a given printer may be built to utilize common thermoplastics deployed in this field, but would not be capable of creating parts from metal.
This may make it seem like 3D printing is more limited in scope than CNC machining, yet this is certainly not true when considering the full gamut of materials that have successfully been used for additive manufacturing. Everything from concrete and latex rubber to biological tissues can be used to make objects and structures with the right equipment and software.
As such if you are making a choice between a CNC machine and a 3D printer, it is a matter of prioritizing either all-around material versatility or the perks of uniqueness and the potential for specialization.
Accessibility & automation
While there is room for debate over a number of comparisons between CNC machining and 3D printing, the one area where the argument is essentially settled is accessibility.
3D printers are less technically challenging to use and generally more user-friendly, hence why you can buy equipment from this market that is designed specifically for use at home. Conversely, even the most basic CNC machines are made with experienced enthusiasts and trained professionals in mind, with the expectation that their primary use will be commercial rather than domestic.
Automation is of course integral to both of these approaches to manufacturing, although the extent to which it is applicable varies. When a 3D printer is set to run on a project, it should be able to complete it without the need for operator intervention, barring any serious fault or problem arising. When a CNC machine is set to work, it may need an operator to monitor, interact with and make adjustments at certain points in the process.
Of course, CNC equipment is always making progress towards increased automation, with models able to swap between different types of tooling automatically rather than requiring manual change-overs, for example. Even so, this divide in accessibility looks set to remain, making 3D printing a tool for the masses while CNC machinery primarily targets business users.
Precision & complexity
The final areas in which CNC machining and 3D printing trade blows are the precision with which they operate and the geometric complexity of the objects they can produce.
CNC equipment takes a clear lead in terms of making parts with incredible precision, hence why it is the first choice for manufacturing in industries like aerospace where tolerances are especially tight. Meanwhile 3D printing is capable of creating geometrical shapes that are incredibly challenging or outright impossible to achieve with any earlier form of manufacturing tech.
Speed & output
Arguably the most noteworthy difference between CNC machining and 3D printing, and upon which their suitability for a plethora of projects hangs, is that of operational speed and thus output potential.
As already mentioned, 3D printing is better suited to complex geometries, but it can take hours or even days to complete especially intricate projects, building up one layer at a time. It is of course possible to create simpler shapes with additive manufacturing as well, but this is also a sluggish process.
This is where CNC machining comes into its own, because it can leverage automation and operational rapidity to turn base materials into simple parts in a jiffy. More significantly still, it can do this time after time, making it ideal for larger production projects where speed is of the essence and volumes are greater.
In conjunction with this speed come lower costs for higher volume production runs. The more time it takes to make parts, the greater the cost, so when going head to head with 3D printing in certain scenarios, CNC machining is the victor in terms of value.
There are positives and pitfalls to both CNC machining and 3D printing, and it is the difference between them that allows them to both be viable in the modern market.
Indeed your needs might necessitate the use of both technologies as part of the prototyping and manufacturing process for your next project. It is simply a case of considering all your options and not ruling out either approach by default.