(photo: GE)

Have you heard of digital twins? The idea was first developed in the 1960s as a way to create a lifelike model of the Apollo mission to help assess its "failure" through a physical model of the vehicle with digital components. The concept has understandably grown since then, but the core remains the same. Essentially, a digital twin is a virtual model that is designed specifically to accurately reflect a physical object. Not only that, but according to IBM, a digital twin can be seen as "a virtual representation of an object or system that spans its life cycle, is updated by real-time data, and uses simulation, machine learning, and reasoning to help make decisionsAlthough often mistaken for just modeling, digital twins go beyond that. The use of algorithms and math in digital twins is an important part of allowing users to predict the behavior of parts such as those made with 3D printing.

They have found their place in various applications from manufacturing to medicine and even interior design. In addition, they are increasingly used in additive manufacturing. Although this is perhaps not surprising given the fact that the digital twin market was already estimated to be worth $6.9 billion in 2022 and will grow to around $73.5 billion by 2027 according to Markets and Markets. But why exactly would you use digital twins in 3D printing? What should you know before you do? Let's take a closer look.

Digital twins are increasingly used as part of Industry 4.0 (photo: GE)

Using digital twins in 3D printing

Digital twins and additive manufacturing are considered to play a key role in Industry 4.0. Only in recent years, however, have the two begun to combine. However, it is important to note that many different studies have found that 3D printing is generally very suitable for the use of digital twins. Why? Because additive manufacturing is inherently digital. From online design to slicing software to programs that monitor the entire printing process, automation and AI have already found a home in AM for this very reason. Digital twins would be just another tool to add.

But how to use them? Well, let's first look at the process of integrating digital twins into 3D printing. As mentioned earlier, a digital twin starts as a 3D model. This can be done using CAD or generative design software. Additionally, 3D scanning is increasingly being used as it creates a perfect model of the part in question. In addition to the initial design, there are now a number of software programs on the market that are designed specifically to work with digital twins, including 3D printing. Take for example those from Siemens, Simio or Netfabb. This makes integration easier, thereby further spreading usage in general in AM. Not to mention, it's easy to see how it could be used for applications like reverse engineering spare parts, thanks to its ability to truly recreate products.

Finally, there are several different forms that digital twins can take, so that should be considered as well. According to one report, digital twins can be divided for additive manufacturing into four categories: process digital twins; equipment digital twins; digital twins of facilities; and product digital twins. As their name suggests, they target different areas in the production process. Process digital twins can be used to replicate a digital version of the 3D printing process for design, manufacturing and maintenance. Likewise, digital twins of equipment can replicate printers, providing important information for maintenance work. The digital twins of the facilities are a mixture of the first two, but on a larger scale, taking into account the entire factory. Last but not least, and what we will mostly discuss in this guide, digital product twins are representations of a product and part, allowing it to be optimized, tested, designed and analyzed to predict performance.

Introducing how digital twins work with 3D printing (photos: Zhang, Li, Xiaoqi Chen, Wei Zhou, Taobo Cheng, Lijia Chen, Zhen Guo, Bing Han and Longxing Lu)

Why integrate digital twins into AM?

There are quite a few advantages to the combination of digital twins with 3D printing as well. Especially when it comes to parts quality control. Although AM has changed a lot from its origins as rapid prototyping, with more and more end-use parts coming to market, quality control remains an issue. Indeed, by its very nature, AM often requires extensive testing to ensure the correct parameters to prevent printing errors. But this is in direct contrast to two of AM's biggest advantages, namely cost and materials reduction.

Fortunately, through the use of digital twins this can be solved. Digital twins allow users to directly evaluate parameters thanks to the continuous flow of data due to feedback. This, in turn, allows optimization of the mentioned parameters without the need for physical tests. Additionally, with digital twins, real-time monitoring is possible throughout the 3D printing process, allowing for even greater accuracy in the final prints. This in terms of makes quality control for AM more reliable. This is especially important when it comes to more industrial processes, including metal AM through methods such as the laser powder bed process, as this can also increase consistency.

In addition, as described above, digital twins are not only used for individual parts. In fact, they can be made for an entire factory. This would make industrialization especially more feasible for additive manufacturing, as 3D printer farms can be optimized not only on an individual level, but also on an entire floor for more efficient production. 

That doesn't mean there are still challenges. The actual definition and development of a digital twin is still quite difficult, not least because many scholars have noted that the framework itself is not well understood. However, the more digital twins and 3D printing are used together, the faster this hurdle will be overcome. And this is already happening on a larger scale, especially with the increased use of AI and more sophisticated machine learning tools. It will certainly be interesting to see how digital twins and 3D printing are used together in the future and how this will change.

We can probably expect to see increased use of digital twins in 3D printing, especially for parts like turbines (photos: Konica Minolta)


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