3D Printing vs CNC Machining

A. Processes

3D Printing:
In 3D printing, prototype parts get built by the addition of materials layer by layer – thus, the term additive manufacturing. All 3D printers are additive but where they differ is how the layers are built. A few methods include the use of curing, extruding, or sintering the material in order to produce these layers. Prototyping is key to successful product development, as it gives you the advantage of fully evaluating a product’s form, fit, function, and appearance before advancing it into production. 3D printing helps speed up this process, as parts can be redesigned and sent to be reprinted as many times as necessary. Below is an example of a typical 3D printed prototype which offers higher mechanical properties as compared to a traditionally casted part.

Advantages:
• Complex, intricate and lightweight prototypes with good mechanical properties can be produced
• Speeds up the product development process
• Scrap is reduced

3d printing process

 

CNC Machining:
Computer numerical controlled (or CNC) machining is a process where prototypes are created by removing material with unsurpassed accuracy. Since this method of production removes excess material, subtractive manufacturing is also used as a common term for machining. Because of the precision possible with CNC machining, this process can produce parts with critical dimensions. This is the reason why CNC machining is used for not only prototyping but also low volume manufacturing of plastic and metal parts. Below is an example of a typical CNC machined prototype.

Advantages:
• Parts can be identically produced over and over
• Allows for a wider range of materials to be used including plastics, foams, metals, and even composites
• Manufacturing of large parts possible

cnc machining process

B. Materials

3D Printing:
The number 3D printing materials is constantly growing. Fused deposition modeling uses thermoplastics through a material extrusion process. Stereolithography uses liquid photopolymers which include ABS-like, Flex, and WC. Selective laser sintering uses a bed of powder which is sintered, and these materials include PA, GF, and EX. Direct metal laser sintering is a similar technology, but uses only metal alloys such as Inconel, Stainless Steel, Aluminum, Titanium and Cobalt Chrome.

CNC Machining:
Machining materials include a wider range of plastics and metals. These materials include ABS, PC, PEEK, and PP. Other materials that may be used including PA, High & low density urethane foams, Acrylic, Delrin™, Aluminum, and Composites.

C. Finishes

3D Printing:
Most 3D printing methods require removal of any supports that were required to be built with the prototype part. Once these supports have been removed, master craftsmen hand sand, blast, and paint the surfaces of the prototype part to meet the details as specified by the client. Depending on the technology used, these prototypes can be finished to be as convincing as the customer needs them to be.

CNC Machining:
Machined parts require slightly less post-processing than additively made parts. Once the part is complete, any required chrome plating, anodizing, specialty plating, paint or texture can be applied to create a near-perfect rendering of the original design.

D. Applications

3D Printing:
3D printing offers the advantage of evaluating a product’s form, fit, appearance, and overall functionality before getting into production. It is ideal for housings, enclosures, impellers, connectors, snap-fit designs, thermally stressed prototype parts, living hinges, sporting goods, automotive and aircraft interiors, grilles and bumpers, turbine components, and fans.

CNC Machining:
Machined parts are ideal to produce a small or large quantity of parts. It is ideal for industrial enclosures, machine guards, structural parts, fabricated components, medical devices, analytical instrumentation, and insulators.

Created by RedOrum