In this quick guide, let’s breakdown the difference between 3D printing VS CNC machining. We will talk about what’s best for prototyping, material strength, ease of use and cost.
Differences In Manufacturing Processes
The key difference between 3D printing and CNC machining is the following:
3D printing is a form of additive manufacturing (Parts created layer by layer using FDM, resins, plastic and metal powders)
CNC is subtractive (Starts with a block of material, also known as blank. The machining tool will cut away material to create the final product)
Creates stronger parts
Much smoother surfaces
Faster removing material than 3D printing can deposit it
Post processing requires more time
Skilled labor intensive, Supervision required
Big mess to clean up afterwards
Highly flexible to create whatever shape you want
High geometric complexity
Works for most manufacturing sectors
Fast for prototyping & mold creation in just a day
Cut costs and time
Much easier to make small parts
Metal printing still needs improvement for stronger structure integrity
Poor surface quality
Both 3D printing and CNC machining work for a wide varity of materials including:
3D printing currently is more geared towards plastic printing. These common thermoplastics materials include:
As metal printing technology continues to improve, and we are excited to see what that will look like in the next 10 years.
CNC machining generally involves aluminum, and it can also machine the following materials:
If it urgent and there isn’t any holdups to the operation. You have the machine, man power, materials and time…. CNC machine the part.
If you need the part now within 24 hours, 3D printing can speed up the process and free up time for other important tasks
If you’re doing this for fun (not for business), 3D printing is the way to go.
Outsource machined components typically requires several days at minimum, which involves part file review, quote request, purchase agreement, lead time and shipping. It can result in a very length process.
For a large scale manufacturing business, high volume production is generally achieved by preparing a large volume setup. Setup time increases for parts that requires more complexity, and the depend on the geometry, CNC per unit cost drops
3D printing is fast and requires less programming time except for a well configured 3D model file. While the unit cost is not affected much by volume, the challenge comes when more printers are required for scaling up production.
Geometry Level Of Definition
How fine can these manufacturing techniques create a part?
Both CNC and 3D printing processes are limited by the tool size.
For CNC machining, a skilled operator must be able to swap drill bits at the right time of the machining stage to make the desired shape. So the tool diameter dictates the smallest negative feature that can be created.
For 3D printing, the nozzle diameter dictates the smallest positive feature that can be made. (Typically 0.25mm and 0.8mm) This is where we need to pay attention to the minimum fiber feature sizes for continuous fiber reinforcement.
CNC machines are pretty good at producing much smoother surfaces than a 3D printer. While 3D printing can produce parts for fit and finish. For parts that require ultra smoothness for mating with other precision components, CNC is preferred.
Yes we can print it, but will it be strong enough? this is why structural integrity is important to discuss.
Structural parts that can withstand significant physical loads require continuous fiber reinforcement. CNC is much better than 3D when it comes to making parts that can survive high-stress load. Such as firearm parts, aircraft parts, vehicle parts.
To learn more please check out our guide on isotropic fiber fill that explains this topic in greater depth.
Will 3D Printing Replace CNC Machining In The Future?
3D printing technology is a giant leap forward in the engineering world. It can do thing in ways that weren’t even possible before. Both 3D printing and CNC machining have their place in manufacturing.
It will not completely replace CNC machining, and it will serve as a manufacturing force multiplier to make better products.