CNC 3D Printing for Parts

Thursday, April 14, 2016 | By | Add a Comment
A CNC Turning Center in the FAME Lab in the Le...

A CNC Turning Center in the FAME Lab in the Leonhard Building at Penn State. (Photo credit: Wikipedia)

Nederlands: Presentatie van de 3D printer op d...

Nederlands: Presentatie van de 3D printer op de Wikimedia Conferentie 2011 (Photo credit: Wikipedia)

CNC 3D Printing for Parts

When learning about what manufacturing machines suit your needs as a parts designer or creator, there seems to be a universe of factors to consider when finding the best machines to meet your needs.  For those of my fellow readers that have relatively little or no knowledge on these machines, I would like to briefly describe the functionality as well as the fundamental differences and highs and lows of CNC/3D printing for parts.

CNC mills can work on a huge variety of materials: metal alloys (e.g. aluminum, steel alloys, brass, copper), softwoods and hardwoods, thermoplastics, acrylic, modeling foams, machining wax (for creating a positive model for casting).  You may need different cutting tools for different materials, but the tool-to-machine interfaces are usually standardized – so the tools can easily be exchanged.  This way, you can utilize a CNC mill to manufacture prototypes in the same material that will be used for the final product – so you can immediately start testing.

Desktop 3D printers are usually restricted to a few materials, typically thermoplastics (PLA, ABS, sometimes nylon) or resins. Thermoplastics can be mixed with other materials such as ceramics, wood, metal, but the workpieces produced on a 3D printer will not be as robust as workpieces cut from a block of metal or wood.  As thermoplastics and resin 3D printers use completely different methods, a resin printer cannot handle thermoplastics and vice versa.  These machines are far from perfect and the ability to create precision parts depends on a variety of factors.  In practice, dull or damaged cutting tools, worn mills or faulty data delivered by the CAM software may result in inaccurate workpieces.  Precision in 3D printing is far from perfect and many parts can have many flaws and errors in their creation.  Some 3D printers promise very high precision but fail to deliver it from time to time.  Precision also relies on the capabilities and skills of the programmer/user, and there is a lot of learning and trial and error that goes along with using these machines.

Comparing speed is difficult as CNC mills and 3D printers are typically used for different workpieces and materials.  However, 3D printing jobs often take hours to complete, whereas CNC milling jobs with comparable size and complexity normally do not take more than an hour.  CNC mills are typically faster when chipping away material from a solid block than 3D printers that build objects layer by layer and occasionally have to slow down to avoid printing problems.

Depending on the material used, CNC milling can get extremely noisy.  Cutting metal or wood using a large-diameter tool (to quickly remove large parts) can be ear-deafening.  The rattling noise from a desktop 3D printer without casing is like a gentle waft in comparison.  When cutting wax models, the noise from a CNC mill is hardly perceptible, however.  When working on a metal or wood block, a CNC mill also vibrates heavily and you wouldn’t want to have it on the desktop near you (even if you wore ear defenders to block of the noise).  Vibration normally is no issue when 3D printing.

CNC milling means cutting away material using a rotating tool.  So, as a result there is a lot of material spurting away, and that may be quite sharp (e.g., splinters of wood or metal).  Not all CNC mills are fully enclosed when working on a block of material, so things can get quite messy.  And with enclosed mills, you have to clean up the mess inside, once the workpiece is finished.  3D printing is not messy by design.  When something goes wrong, however, you may need to remove thermoplastics from your printbed.  But that is nothing compared to cleaning up after CNC milling.  By design, there is less waste in 3D printing as this technology only requires the material needed for building the workpiece.  In CNC milling you need a block of material that has at minimum the size of the workpiece and a lot of material has to be removed and often cannot be recycled.

CNC milling is the better solution when manufacturing workpieces that need to be extremely robust and precise and/or heat-resistant.  3D printing has more exotic fields of application: It can be used for bioprinting, for printing food, for building purposes, and it can be used in space (e.g. on the ISS or in future space missions).

Pricewise, getting started is less costly with 3D printing: You can get decent 3D printers for about $500, while the CNC mills featured on Kickstarter recently start at $2,000.  Technology in these machines however is rapidly advancing and new developments are continually being rolled out including a machine that has the functionality of a CNC machine, 3D printer and laser cutter/engraver combined.  So, if you want the best of all worlds, you may want to wait a little while to purchase a machine to cater to all your needs.

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , ,

Category: 3D Printing, 3DS Max, Art, AutoCAD, Avant Garde, CAD, CAM, CNC, Commercial, Cosplay, Design, Drafting, Fashion, Gaming, Manufacturing, Print, Role-Playing, RPG, Smart Clothing, Solidworks

About the Author ()

Leave a Reply