A Look at Additive Manufacturing and Its Potential In Production
3D printers have come a long way over the years, but can we really expect to see them on the factory floor, taking the place of large machining centers? What benefits and challenges does printing offer to manufacturing?
What Is Additive Manufacturing / 3D Printing?
Additive manufacturing (also commonly known as 3D printing) includes processes for creating objects by adding material rather than cutting or drilling. One of the most common methods is fused deposition modeling (FDM), the process of adding material in thin layers per pass of a printing head. FDM has some similarities to a typical desktop printer that you might find in a home or office, where each pass of the print head prints one line of the image or text per pass.
3D printing works on the principle of extruding or solidifying a material with heat or lasers one layer at a time. Servo or stepper motors are used to move the print head or build surface along the X, Y, and Z planes. 3D modeling (CAD) software is used to create the component in the virtual world, and special software is used to convert that 3D model into coordinates that the printer can use to make the component. This process illustrates one style of 3D printing, but many others print plastic and metal components.
Figure 1. HP's lineup of industrial 3D printers. Image used courtesy of HP
Advantages of Additive Manufacturing
The most obvious benefit of 3D printing is less waste. Typical manufacturing requires starting with raw material, which is larger than the final component, loading that raw material into a machine then removing the material until the required size is reached. The waste then needs to be removed from the machine and disposed of, or perhaps recycled at great expense. With 3D printing, the raw material could be a spool or bag/hopper of the printing medium. When these machines are installed in an automated environment, the replacement of this medium can be automated so that the 3D printer never needs to stop.
In contrast to modern printing processes, plastic mass manufacturing typically employs injection molding machines where plastic pellets are melted and injected at high pressure into a highly polished and accurate mold. Automation is used to open the mold and remove the completed parts, but deburring and finishing are usually required after the parts are removed. The overall equipment needed for injection molding can be very costly and requires a lot of maintenance. With 3D printing, the machine is mostly self-sufficient with relatively little maintenance, and finished components typically don’t require deburring.
3D printing machines are mostly autonomous, provided they have enough material to make the part. Once the file is loaded into the machine, it will continue to run until the part is complete or the printing medium needs to be refilled or changed. This style of manufacturing could lead to a “lights out” style where there are no operators tending machines and no lights on in the room. Printing status could be reported to a website, or alerts could be sent to operators or maintenance staff when attention is required.
Figure 2. Some 3D printers can create entire circuits in a single automated assembly step. Image used courtesy of Nano Dimension
Drawbacks of Additive Manufacturing
One of the most well–known drawbacks to any additive process is the time it takes to print any part. Creating custom parts is quite easy, but mass production of identical parts provides no time or cost saving over printing only one-off projects. For this reason, it is commonly reserved for R&D situations before a more efficient process can take over mass production.
‘Built for automation’ is a term machine builders use to describe features or processes that can be integrated into an automated process. Not all process or manufacturing machines are built for automation. If you are using a robot to load and unload a machine meant for human operators, you need to consider how the robot might open the doors or how the robot should locate features on the part for suitable gripping. Most cost-effective 3D printing machines are not built for automation, preventing the efficiency gained by process automation.
Some of the plastic additive printers require the part to be released from the printing bed—the robot won’t be able to gently move, shake, or rock the part until it releases. Some metal printing/sintering machines use a powder medium, and the finished parts are buried underneath the medium. If a camera cannot locate the gripping features or the part is not located with tooling, the robot will have a hard time picking it up.
The 3D printing equipment requires advanced controls, sensors, and servo motors to produce highly accurate components making the machines very expensive to acquire, operate, and maintain. Some machines are cost-effective but lack accuracy, surface finish, and speed.
Figure 3. Although printing is slow, the ease of the process and the low capital cost can benefit large-batch manufacturing. Image used courtesy of Unsplash
Progress in Additive Manufacturing
Over the years, many advancements in 3D printing have made the process more attractive to production. One such advancement is the diversity of materials that can be printed. It wasn’t long ago that only plastic could be 3D printed. Today, many different kinds of materials exist, including conductive traces and substrates for circuit boards. Nano Dimension has a 3D printing machine that can print an entire circuit board with a substrate, conductive traces, and many passive components. Adding this printer to an automated assembly line could reduce supply chain strain by not having to rely on overseas vendors to produce circuit boards.
The assembly process of any product is typically a whole difficult stage of automation. Many parts do not assemble easily or are too difficult to hold with a robot gripper. Some of this assembly time can be reduced with 3D printing capable of printing different materials simultaneously. HP is working on a printing process where each voxel (pixel with volume) can be controlled. This process allows the possibility of embedded components without the need for assembly. Circuit boards could be created inside the component while the component is being made.
The above advancements combine multiple processes into one machine, reducing dependency on vendors and reducing handling issues within the factory. As these companies and others continue to advance the 3D printing technology, we will likely see more 3D printers in factories and larger-scale production environments, capitalizing on the strengths and solving the weaknesses, just as all technology has done for generations.