Choosing the right manufacturing technology for prototypes and functional parts is not always an easy task. Even the most experienced designers can get stumped when trying to choose between CNC and 3D print for their project.
In the past, 3D printing was limited to plastics, but new developments have rapidly transpired in digital manufacturing technologies over the years. Today, metal has become a standard process in 3D print, and many industries are also utilizing other materials as well, including ceramics, composites, sand, and wax.
Without substantial knowledge of financial and design perspectives, key benefits and solutions for engineers can be easily overlooked. This article will present key technology factors to consider when choosing the right technology for your functional parts and prototypes.
CNC or 3D Printing?
The first thing to understand is the differences between CNC machining and 3Dprinting.
CNC stands for “Computer Numerical Control”, a process where a computer converts’ computer-aided design software (CAD) into the coordinate numbers of a graph that controls cutter movements.
It is also known as subtractive manufacturing technology since it involves subtracting pieces from a block of material using various cutters or rotating tools to achieve a specific design shape.
CNC machining is the more common method used for manufacturing small one-off jobs to high volume production since it provides a wide range of surface finishes and materials as well as high accuracy and superior repeatability.
3D printing is more commonly known as additive manufacturing (AM) as — opposed to CNC that subtracts materials while processing — AM adds materials one layer at a time, but doesn’t require any special fixtures or tooling; therefore, the initial setup costs are basically kept at a minimum. The most suitable processes used for plastics when printing in 3D are FDM or SLS and for metals, Binder Jetting or SLM/DMLS.
When choosing between AM and CNC, there are a few simple guidelines that can be applied to help you decide which is best for your technology project.
A good rule of thumb is, all parts that can be manufactured through a subtractive process with limited effort should basically use CNC services. CNC produces parts with better mechanical properties and greater dimensional accuracy. However, this typically comes at a greater cost, especially with smaller volumes.
On the other hand, when implemented properly, a good AM strategy can significantly reduce the number of production steps, the number of specific parts required for assembly, how much inventory is held, and material waste.
What if higher part quantities are needed?
If hundreds of parts are required, then neither AM nor CNC may be a cost-competitive option. Generally, the most economical options are traditional forming technologies, such as injection molding, due to mechanisms of economies of scale.
How to get your parts fast in the technology you need
Once you have decided if using CNC machining, 3D print, or Injection Molding is the right technology for your project, a manufacturing platform can help you get your parts fast and hassle-free.
With 3D Hubs, you can simply upload your designs, to get an instant CNC quote and the automated Design for Manufacturing (DFM) analysis will detect any potential issues even before production begins. Instant quotes are also available from 3D Hubs online 3D printing service and for injection molding.