A True Masterpiece of Machining

The role for Artificial Intelligence in manufacturing is emerging day-by-day, but a recent project by cutting technology developer Sandvik Coromant has revealed a significant creative potential at the nexus of design and craftsmanship.

Sandvik Coromant engineers Henrik Loikkanen and Jakob Pettersson were tasked with creating an AI- generated combination of some of history’s most famous works of art, rendered in stainless steel – putting their metal cutting expertise to the test. Working with Sandvik Group, Sandvik Coromant used AI modeling and cutting-edge manufacturing to create a new sculpture that combines design elements of work by Michelangelo, Auguste Rodin, Käthe Kollwitz, Kotaro Takamura, and Augusta Savage, bringing together some of most famous artists from the past 500 years.

Weighing 500 kilograms and standing at 150 cm tall, the “Impossible Statue” was inaugurated at Sweden’s National Museum of Science and Technology, Tekniska Museet in Stockholm, in April. Producing a statue in such a way has never been done before. So

How did Loikkanen, Pettersson, and their team blend art, science, past, and future into a three-dimensional work of art like none before it?

AI has been around for some time, with intelligent machines performing activities that normally require human intelligence, such as visual perception, speech recognition, decision-making, language translation and problem-solving. The concept dates back decades, but new, conversational AI programs such as Google’s Bard and ChatGPT open up even more applications. Now, AI can create art.

Completed design

After establishing a 2D design that brought together the styles of the five artists, Sandvik began translating the model into a complete 3D image.

Using depth estimators to build the 3D model, human pose estimators to refine the body, video game algorithms to generate realistic fabric and specialized AI to reintroduce fine details that were lost in previous steps, Sandvik began turning the design into reality, using Mastercam software to convert the CAD model into an object with over six million surfaces and multiple complex details.

“We needed a phenomenally precise digital simulation to help us machine the statue,” according to Henrik Loikkanen, technology area manager at Sandvik Coromant. “Digital manufacturing means we can prove out that whole complex machining process beforehand. The only time we spent on machines, therefore, is actual production time. It also meant we didn’t produce a single scrap component during the entire project.”

After finalizing the statue’s design with AI and virtually simulating optimal ways to manufacture the statue using digital twinning, it was time to start machining. “We treated producing the statue as we’d treat machining highly specialized, complex parts like those found in the aerospace industry,” Loikkanen continued.

“An additional challenge came from the statue’s chosen material — stainless steel from Alleima — as ISO M materials are notoriously difficult to machine,” he detailed. “The material group is characterized by its high work-hardening rates and poor chip breaking properties during machining. Therefore, careful attention must be paid to the tools selected for machining the material.”

Tool selection

Sandvik Coromant chose several tools to help sculpt each intricate part of the statue. The Coromant Capto^® tooling interface was used to connect the arm and head to the torso of the statue, solid round tools from the CoroMill^® Plura and Dura families were used to finish all the statue’s surfaces and features; the CoroMill MH20, a high-feed milling cutter (introduced in 2021) was used to machine the bulk of the stainless steel removed from the workpiece.

“We have more than 10,000 standard products covering drilling, milling, reaming, and threading in our back catalogue,” explained Jakob Pettersson, CAM and machining specialist at Sandvik Coromant. “But we couldn’t select just any tool to create the Impossible Statue. To pull off such a manufacturing feat, we needed to be laser-focused on our selection.”

Pettersson continued: “We had to give the method and tooling selection extra thought in order to use as little tooling as possible and thereby limit waste. Rough machining of the statue was done with a mix of solid-carbide end mills from the CoroMill Plura and Dura families. The rough profiling of the final shape had to be made with rather long tooling. Here, a combination of MH20 high-feed cutters mounted on heavy metal shanks was the perfect fit. The use of end mills from our solid round tools offering greatly sped up the process and therefore reduced energy consumption.”

The CoroMill MH20’s ability to machine at long overhangs makes it effective for aerospace parts production. It was designed for difficult-to-machine components, with a two-edge insert rather than the more typical four-edge style. This means the weakest section of the insert is far away from the main cutting zone, for greater reliability and protection against wear. It also means that machining against a corner or wall will not impact the next edge or leading corner, so there is equal performance per edge.

CoroMill Plura HD is for heavy-duty steel and stainless steel machining, offering safe and efficient solid end milling. CoroMill Dura end mills can be used in all processes needed to produce a component ― including roughing, finishing, semi-finishing, and ramping.

Master machining

The Sandvik Coromant team made several adaptations to their machining strategy. “The initial 3D model was not the type of model CAD/CAM systems can work with,” Loikkanen recalled. “It had to be converted from a 3D-mesh model, which is essentially a shell of surface polygons commonly used in 3D animation studios, to a solid 3D model with density, and that was a pretty challenging process.

“Once completed, the model was sectioned into 17 pieces, and all interfaces between them had to be modelled with a tight fit to make the intersections invisible when the parts were put together,” he further recalled. “It took time to get everything perfect.”

“We also had some challenges during rough machining due to the size of the component in relation to the machines,” added Pettersson. “This was solved by simulating NC-code and finding all the areas where we would reach the machine work envelope limit and by altering the CAM sequence.”

But developing a never- seen-before statue wasn’t the only accomplishment for Sandvik Coromant. “Along the way, we implemented several techniques that can be applied to future digital machining projects,” said Loikkanen. “Because of the pure amount of programming work, building the statue would have been impossible without a digital twin. All the testing was done digitally to save a huge amount of time that would otherwise be spent on trial-and-error testing. This is certainly something we can apply in future projects to save time and reduce the number of scrap components.”

Pettersson noted that programming and simulation became faster and faster as they proceeded with each component. “Machining took about the same time throughout, mainly because the cutting data and tooling selection never changed that much,” Pettersson said. “This point brought me to one conclusion: the extensive product data and recommendations we give are accurate and are easily attained either from our website, tool guide, Tool Library, or even integrated directly in CAM systems themselves.”

The statue is now on display at the museum in Stockholm, exhibiting the creativity possible with both digital and physical manufacturing tools. “I’m incredibly proud we’ve pulled this off,” according to Loikkanen. “Hopefully those visiting Tekniska Museet, and anyone else who sees that statue, can appreciate that it’s an artwork like no other.”

“The techniques we used and the methods we employed really show what Sandvik Coromant can do,” added Pettersson.