Will metal 3D printing replace CNC machining?
Despite the promising nature of these metal additive technologies, they will not replace CNC machining completely.
For many years now, CNC machining has been the go-to precision manufacturing method. This process involves using computer software to move tools and machines for the creation of parts. However, there is a new contender in the picture – Metal 3D printing.
The boom of Industry 4.0 sees more developers open their doors to manufacturing using 3D printing. The metal additive technique continues to transform the manufacturing industry. Numerous applications of this technique are going to the forefront of production.
The common question in the industry today revolves around choosing between CNC machining and 3D printing. While 3D printing proves to be an effective process, will it replace CNC machining? To answer this question, we need first to consider some factors that influence selection decisions.
How Does Metal 3D Printing Compare to CNC Machining?
CNC milling service has been the staple of manufacturing since its evolution, while 3D printing may seem a little novel. However, 3D printing builds objects a single later at a time, helping to create parts as effectively as possible. One of the greatest benefits this system offers over traditional methods is the speed of production.
This does not mean that manufacturers abandon CNC machining. Both production approaches offer benefits that make each of them well-suited for differing objectives. Here are some of the factors that help to compare these processes and their effectiveness:
When you compare the surface quality of CNC machined parts with 3D prints, you’ll notice the difference in quality. CNC-produced parts can move from production to the market as soon as required. However, 3D prints often require different steps to finish the production tasks. This perceives the 3D printing process as a less effective process than CNC milling.
3D printers do not have the precision needed for mission-critical uses. Even when engineers use Selective Laser Melting technology for printing 3D parts in metal, its accuracy can’t match that of CNC machines. For example, 5 axis CNC milling can create mechanical accuracy of 1 micrometer on each of the axis. This level of accuracy is not possible with currently available 3D printers.
The CNC milling process begins with machining a block of material to meet design specifications. This process is one that can trade accuracy for speed whenever speed becomes a crucial factor. This gives operators better control over the production time. Using metal additive manufacturing takes longer than subtractive processes.
The conventional 3D printing process involves the slow creation of layers to get the desired product gradually. The 3D printer itself determines the speed of the process. In some cases, manufacturers use faster printers when speed becomes a factor. Even at that, 3D printers will find it hard to keep pace with CNC machines.
There are several 3D printers available, making it challenging to compare them with CNC mills. Moreover, 3D printing output requires post-production processes, increasing the time to make components. Generally, CNC machining offers benefits in speed over 3D printing.
Comparisons between the costs for 3D printing and CNC milling often come in general terms. The definition of units usually varies between materials, customers, and jobs. Price considerations are one of the major factors while deciding between using a CNC router or 3D printer.
When it comes to using CNC machines to create parts, small quantities are usually associated with a higher unit cost. However, large batches are often more economical, making CNC ideal for mass production. Unit cost for products here can increase based on the precision and complexity of the output. The higher cost may be due to larger tool paths needed and the amount of time needed for job completion.
Metal 3D printing, on the other hand, has every output unit costing the same. The price of the output unit remains constant, regardless of the size of the batch. Having equal cost for every unit in small-volume productions represents an advantage. However, uniform cost per unit for large-volume productions can become a problem.
3D printers use additive and layering processes, making them unsuitable for large-volume productions. Current 3D technologies can only scale from producing small customized parts to medium-sized objects.
On the other hand, CNC routers are capable of scaling between creating small and larger outputs. The scale of parts created often depends on the machine’s capabilities. Many times, the scale also depends on the raw materials involved in the production.
Although 3D printers look to evolve to create bigger products, they currently do not have the capacity for extensive production like the CNC machines. Moreover, the time taken for 3D printing limits the feasibility and scalability of the technology. However, its flexibility allows for quick switching between different jobs.
3D Printing, A Complement to CNC Machining
Companies that use metal 3D printing have the vision of reducing the cost-per-part to make additive manufactured components move towards large volume productions. This will move this method in the direction of the industry for high-end production parts.
New technologies are in a steady movement towards this direction. Metal additive manufacturing now occupies a good space between prototyping and full line production. Also, we now see cases where 3D printing creates complex geometrics. Thus, it offers faster and more cost-effective solutions in such cases.
Despite the promising nature of these metal additive technologies, they will not replace CNC machining completely. At least, they won’t do that any time soon. Rather, 3D printing will remain in its own sizable niche within the extensive array of metal fabrication processes. At the same time, CNC milling will also retain its place for a wide range of applications. This will especially be true for parts that require extremely tight tolerances.
Furthermore, 3D printed parts usually have to go through post-production finishing. These often include cleaning, washing, polishing, and several others. On the other hand, only a small amount of CNC machining will give near-net-shape parts for tight tolerances. Therefore, metal additive parts and CNC milling parts will continue to co-exist for years. These technologies will complement each other for several manufacturers in the 4.0 industry.