CNC Machine vs 3D Printing: The Best Option For Medical Machine Parts

Medical CNC machining has been the defacto standard for producing medical devices and machine parts for decades.  In recent years, though, 3D printing has entered the field.  Sometimes it can be confusing trying to figure out which technology is better suited to a particular situation.

Nothing in Common

It would help if the two technologies were more compatible.  Medical CNC machining is a subtractive technology -it removes material to form the desired part.  3D printing, however, is additive, layering the fluid material to form the part.  There is no native file format shared between the two technologies.  The language of 3D printing is concerned largely with layer thickness and supporting the part during printing, while the languages used for medical CNC machining have completely different focuses.   3D printed parts also shrink during curing, which means their files have to specify in what directions and to what degree the part is printed oversized.  That’s simply incompatible with CNC machining.

Form Ultimately Follows Function

Medical devices often rely on prototyping during development.  Prototypes can range from non-functional placeholders to see how a component fits into a device, to perfected pieces which have been tweaked for features, functionality, and production steps.  3D printing can be a suitable technology for those early-stage prototypes.  They are seldom concerned with surface finishes, and often the fitting isn’t critical.

As a medical device moves through the development process however, prototypes necessarily become more refined and functional, with fittings, measurements, finishes, and functionality being incorporated into the design.  In the background this also involves supports, hold-down tabs, and other fittings required for production of the part.  If the functions of the part are better suited to CNC machining, it makes little sense to prototype it via 3D printing and then translate that experience to CNC code for manufacture.

The Shaping of Things to Come

There is no question that 3D printing has a tremendous role and promise in creating models of medical imaging for surgical preparation.  That technology has revolutionized many procedures.  This often extends to custom medical implants based on a specific patient’s needs using a wide variety of materials, including ceramic and sintered metal.  These, however, are one-off or limited run applications, not standard production.

Medical CNC machining, on the other hand, works with an even greater variety of materials, and is far better suited to production.  It produces far better surface finishes than 3D printed parts.  The hardest or strongest 3D printing materials simply are not as durable as materials which can be used in medical CNC machining.  Lastly, the shrinkage inherent in 3D printed parts -especially in materials which require firing- creates greater difficulties in meeting exacting specifications for medical devices.

It’s easy to think of 3D printing as being faster than medical CNC machining, but that’s simply not the case.  3D printing is slow even in the best circumstances.  It’s even slower when printing medical devices because the layers are at the finest level possible to provide the best possible finish.  If a part has been designed by medical CNC machining, that design can be tweaked and the part is re-created from scratch faster than it could be reprinted.  Medical CNC mills can often run lights-out, allowing multiple copies to be produced.  3D printers rarely have that capability due to the separation, cleaning, and curing processes which are required following printing.

3D printers have their place in the medical industry, and no doubt their roles will expand as the technology matures.  That said, now and for the foreseeable, medical device design and production is almost exclusively the realm of medical CNC machining.

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