3D Printing or CNC Machining: Which one suits your project?

When it comes to manufacturing, there are 2 processes that are commonly used. They are 3D printing and CNC machining.

3D printing and CNC machining are similar in some ways. Both of them are computer-controlled solutions. Aside from that, these two manufacturing methods are compatible with STL and OBJ files.

CNC Machining and 3d printing are evolving to meet different manufacturing demands. It is vital to know the difference of these methods to decide which one will suit your needs the best. With that, below is a blog post about the difference between 3D printing and CNC machining.

3D printing vs CNC Machining

Basically, 3D printing and CNC (Computer Numerical Control) machining use different processes. 3D printing is a method which a material is added layer by layer to form a mass that assumes the shape of the product design. This additive technique makes 3D printers flexible enough to create variety of outputs.

On the other hand, CNC machines start with a block of material such as wood, aluminium, etc. Using sharp rotating cutters/tools, the material is cut away or removed until nothing remains except the intended product. This process is called "CNC pecision Machining" Or "Subtractive manufacturing".

So how can you determine if the process is suited for your project? The content below is a more details comparison of the two methods.

Which one is preferred for large-scale production?

When it comes to large-scale production, most manufacturers choose CNC machining over 3D printing. CNC machines can also produce large dense products with great efficiency.

However, although 3D printers cannot produce as many products as CNC machines in the same period of time, very advanced 3d printing machines are usually required. Currently 3d printing is more suitable for small volume type of production and it can help develop prototype a lot quicker than CNC Machining.

Which is easier to use?

3D printers are simpler to use than CNC machineries. With 3D printing, you only need to choose a part orientation, fill and supports for your design. There is no supervisor required once the printing process gets started. Thus, you can leave the printer until the 3d part is completely printed.

While in CNC machining, intensive manpower is needed. There should be a skilled CNC engineering operator to feed the program of instructions into the computer and load the required tools/cutters to the machine.

Which method produces more precise outputs?

CNC machines can produce parts with superior surface quality compared to 3D printers. It provides accuracy since it has higher tolerance to heat.

With 3D printers, it lacks the precision necessary for some applications. Even with Selective Laser Melting (SLM) technology, 3D printers cannot produce parts with the same accuracy as CNC machines.

Which has a wide selection of materials?

CNC machining can accommodate a huge range of materials. This includes metal alloys, thermoplastics, softwoods and hardwoods, acrylic, modelling foams and many more.

Conversely, 3D printing is restricted to less materials due to the limitation of 3d printers and the 3d printing technologies being used. It typically utilises thermoplastics or resins. These materials can be used along with ceramics, metal or wood but it will not be as sturdy as workpieces from CNC machines.

Which method is versatile when it comes to size selection?

CNC machining can produce a wide variety of sizes ranging from tiny and delicate parts to large objects such as refrigerators.

In 3D printing, parts cannot be printed if it is larger than the print bed. There are larger parts can still be printed but you have to break it into smaller components. This means that you have to print it separately then assemble it afterwards. Thus, adding more time to the production process.

Which can create parts with high geometric complexity?

Although CNC Machining has quite a few advantages over 3d printing, when it comes to produce products or components that have high geometric complexity, 3d printing is a winner.

As can been seen above, process A is CNC Machining (Substractive Manufacturing) while process B is 3d printing (Additive Manufacturing). If a 3d object to be produced is very complex, then the cutting and spinning tools required to be used for precision machining (cutting aways materials to make the final part) maybe be changed accordingly and more advanced tools may require.

However, 3d printing create 3d parts layer by layer and in this process, layers of these materials are solidified to form the finished product. Therefore, if supports are available for some 3d printing technologies, regardless how complex the 3d component is, it can be made easily. SLS 3d printing technology and Multi Jet Fusion by HP can even achieve high geometric complexity without requiring any support structures.

Which one is cheaper - 3d printing or CNC machining?

The cost is actually depending on the volume of 3d parts in demand. As explained the advantages and the disadvantages of 3d printing and CNC machining, if large volume of components (usually higher double digits to 100s or even more) with low complexity should be produced for certain project, then CNC machining will be the pick.

If complicated 3d objects with lower volume are required, then 3d printing will be more cost efficient. 3d printing can also meet the goal with shorter lead time, so if you need to get 3d prototypes or components promptly or urgently, 3d printing will be best option.

Conclusion

From the comparison above, 3D printing and CNC machining may overlap in some capabilities. Each of the processes has their own strengths which makes them suitable for different applications.

CNC machining is ideal to use for projects that will require sophistication and precision on the products. While 3D printing will work best for projects such as visual justification, creating prototypes and custom-made projects in low volume with lower cost and shorter lead time

If you need some 3d parts made for your projects, but not sure whether CNC machining or 3D printing is better, then asking for help from a manufacturing company providing both services as they will help you make the decision base on your specific situation.