The manufacturing industry is fast-emerging, with technology evolving at a rapid pace. Whether you are looking at online 3d printing or CNC machining or the new, hybrid 3D printing-CNC mechanism, it is important you weigh the pros and cons of both the methods. In this post, we strive to bring in the key factors to help you decide the best way – additive manufacturing or subtractive manufacturing.
CNC Machining and 3D printing
CNC, the short form of Computer Numerical Control, is a subtractive fabrication method. This means, the layers of the workpiece material like metal, plastic, wood, etc are removed until the custom, the end product comes out. It uses tools like plasma cutters, drills, saws, etc to achieve the desired cut.
Whereas, 3D printing is an additive method. This means the parts are created by adding layers, one at a time, using materials like resins, metal powders, etc.
Factors to consider:
CNC machining cuts through nearly any material. However, the most common ones are plastics such as nylon, ABS, polycarbonate, etc., metals like aluminum, brass, and silver, copper, steel, titanium, wood such as plywood, hardwood, softwood, etc., carving foam, rigid foam, and so on.
3D printing offers much flexibility for manufacturers as it supports a diverse range of materials. In 3D printing technologies, plastics are very common. Note, with environment-conscious producers and consumers and the ongoing market expansion, the industry has sought ways to innovate with ingredients like soybean oil and corn. Hence, plastics are turning into eco-friendly products. Other 3d printing materials used are thermoplastics such as Nylon, ULTEM, ABS, PLA, photopolymers like wax, high-detailed resins, transparent and paintable resin, etc., graphene, nitinol, paper, aluminide, polyamide, and so on.
Accuracy, size, and geometric complexity:
CNC offers tight tolerance – +0.005” or 0.001”/”, whichever is greater, excellent repeatability, and greater dimensional accuracy. It offers precise results for very narrow pieces. It is fast only for simple geometric designs.
3D printing is the winner of exotic materials and high geometric complexity. Complex geometries that can never be thought of in conventional methods, such as 3D structures with cavities, hollow structures, organic shapes, and channels can be achieved.
Both CNC and 3D are being adopted in almost all the industries aerospace, medical, transportation, military & defense, oil & gas, marine, electronics, and so on. CNC machining may be the preferred method because of its reliability and durability.
Although CNC machining is the preferred method, 3D printers overpower in some applications. For instance, the medical field. CNC cannot machine tiny, complex pills that contain life-saving components. In aerospace and defense, for producing complex geometries, and lightweight parts that contribute to fuel saving.
Ease of operating:
The 3D printing process is very simple. Once the file is prepared, a technician selects the orientation, specifies the material, and selects from a list of predefined build options. It takes a maximum of 5-40 minutes. Beyond selecting the orientation, it requires no special skills or experience. Also, the entire process is automated and requires no human intervention until the job is complete.
Whereas CNC machining is laborious and a skilled machinist is required. The CAD file is imported into the CAM program; the processes are defined; decisions are made on the right tool, rotation speed, cutting path, etc. It takes appx 1-8 hours. During the process, the workpiece must be repositioned by the operator from time to time.
As CNC is a subtractive method, it generates huge amounts of waste making it difficult to clean or recycle and you end up spending more.
On the other hand, 3D printing is a sustainable, green technology as only the required amount of material is added in layers. Plus, it reuses the plastic waste for printing filaments and new products. Also, it produces less noise and does not vibrate while printing.
CNC falls under the pricey side if the products are complex, low in number, and requiring a higher degree of precision. It is a cost-effective option, only if the volume is huge in higher double digits. However, it’s worth mentioning that CNC machines cannot run unattended end-to-end and need well-trained operators or programmers in addition to expensive maintenance plans.
3D printing must be your go-to option if you want the prototypes faster. This is also economical for lesser quantities.
Overall, there is no one-size-fits approach to choosing the perfect method. While both 3D printing and CNC both provide different benefits, you may want to know the rules of thumb before selecting the best method.
Choose 3D printing if – your annual production is high in value and low in volume, i.e, below 1,000 parts, materials are flexible, and you desire higher turnaround time at competitive prices.
Choose CNC machining if – you have relatively simple geometrics, need precise and sharp output, and you are ready to shell out more money.
To conclude, with all these pointers you can make a wise choice for CNC machining or 3D printing in Australia, Melbourne, or whichever part of the world you may be in.