Machine OEMs Meet the Moment

Artificial intelligence and automation help modernize machining

As the manufacturing world transforms outside the machine shop, things inside need to change as well. So machine tool suppliers are doing what they can to help shops adjust to the latest production requirements and economic considerations. In addition to upgrading technology in a variety of ways, these companies are assisting customers transition to advanced automation of their machining operations.

Some machine tool upgrades are coming as a result of a strong push from users. For example, electric vehicle manufacturers and others are asking for regular systems with higher spindle speeds and horsepower, according to Tim Thiessen, vice president of sales and marketing at Okuma America Corp., a machine tool builder in Charlotte, N.C. "There are applications that get into (very high) speed machining—35,000 rpm plus—but I’m not talking about that," he said. "I’m saying that what has been the sweet spot within the norm of higher speed machining is moving up."

While Okuma might typically offer 75 hp machines with spindle speeds up to 10,000 rpm, many customers are now requesting 18,000 rpm spindles at 100 or 150 hp, he noted. "It would be one thing if we’re considering that a niche application, but I’m seeing that become more and more mainstream within the industry."

According to Thiessen, Okuma customers want more machine horsepower so they can accelerate to high spindle speeds in a matter of seconds. And they want higher spindle speeds to boost feed rates and reduce cycle times, usually when machining aluminum or titanium, he added.

In addition to making machines more capable, suppliers are trying to make them easier to use. One way is by incorporating conversational control, a text-based technology that lets users input programming information in response to items on simple menus that appear on control screens.

For example, DMG Mori USA Inc. in Hoffman Estates, Illinois, offers what it calls technology cycles, a conversational control option designed to simplify advanced programming for operations such as gear skiving. Instead of creating the necessary program offline, technology cycles "allow complex programming cycles to be input at the machine tool," said Gerald Owen, DMG's general manager of national engineering. They also let operators make adjustments to programs on the fly, he added.

DMG is one of a number of machine makers offering such features. "Combining and simplifying what previously were very high-end functions and (providing) a simpler, easier interface to those is a trend across the industry," Owen said.

Other advanced machine tool features take advantage of developments in the much-discussed field of artificial intelligence. For example, Smooth Ai Thermal Shield from Mazak Corp., Florence, Ky., is included with all of Mazak's newer machines to compensate for thermal distortion of machine components due to temperature fluctuations caused by machine operation or the environment. In the automatic version, sensors continuously gather temperature data, which is stored and analyzed by software that learns from the data so it can make adjustments in process parameters when necessary to prevent temperature-related changes in the machine from affecting part quality.

"The idea is to keep the machine stable throughout the day or machining process," said Jared Leick, Mazak's machining center product group manager. "And the goal is to make sure that you’re getting all good parts off the machine."

A.I. also plays a key role in the operation of Mazak's spindle health monitoring feature. The purpose of this feature is "to prevent a spindle from seizing up or failing while you’re cutting," Leick said. "You don't want to be cutting a $10,000 part and (have) a spindle seize up or stop on you so you have to scrap the part."

Developed in partnership with the University of Cincinnati Engineering School, spindle health monitoring relies on algorithms that compare the vibration and frequency of operating spindle bearings to charts that show vibration and frequency values obtained by testing real spindles. The development team charted data derived from good spindles, defective spindles, and spindles that were at the point of wearing out.

"The idea is to monitor your spindle in real time and send a (signal) to the operator if there's some issue in order to prevent your spindle from failing while it's machining," Leick said.

Another major development in the machine tool industry is the emergence of super-versatile alternatives to dedicated machines for individual operations, which could be called all-in-one machine tools. An example would be a mill-turn machine that can also handle grinding, gear skiving, and advanced metrology.

"That's the industry trend," said Owen at DMG, which makes such machines. "Instead of machines that only do one thing, we’re finally seeing the evolution of machine tools into a one-stop, does-it-all platform."

The advantages of all-in-one machining include improved part accuracy due to fewer setups, as well as the need for fewer different machines on the shop floor. If a single platform can serve as a lathe, a three-axis mill, and a grinder, for example, a shop that requires all three machine technologies doesn't need a separate machine for each technology that takes up valuable floor space, Owen noted. Instead, the shop can get by with a single multifunction machine—or it can fill the same floor space that would be taken up by three single-technology machines with three multifunction machines to greatly expand its capabilities.

Today's all-in-one machines can include more than just multiple machining functions. Owen pointed out that they can also offer functions traditionally performed by peripheral systems, such as advanced metrology. "The advancements in the last five years in metrology on machine tools can be a huge advantage to customers," he said. Instead of purchasing a separate coordinate measuring machine, for instance, "you can basically turn your machine into a CMM. You can use cameras and lasers to measure parts that will give you the same results as a CMM."

On the other hand, Owen noted that the machining capabilities of an all-in-one unit may not match those of a machine designed for a specific operation.

"I would say that a traditional grinding machine is always going to be a little more accurate than a machine tool," he said. So there's probably a point where a dedicated grinding machine would have to be employed, he acknowledged, adding this could be when micron-level accuracies are required.

A modern multifunction machine tool can also be one equipped with a metal additive manufacturing system. Today, these hybrid machines can be seen mainly in the aerospace and automotive industries, according to Eric Wold, regional sales manager at Mitsui Seiki USA Inc., Franklin Lakes, N.J. But Wold believes such machines will eventually be more widely adopted, describing the technology as still being in its infancy.

To illustrate how useful hybrid machine tools can be, Wold points to a customer that repairs impellers. This firm hand grinds away the damaged part of an impeller, then hand welds material back onto the impeller, and finally hand grinds the new material into the proper shape.

"It's kind of a dirty job and doesn't pay very well, so they have high turnover of labor," he noted.

As an alternative to this manual procedure, Mitsui Seiki offers a machine that can remove the damaged area of an impeller with a subtractive process, then build it back up with an additive system that uses a laser to fuse successive layers of powdered metal. When the layer-by-layer additive process is completed, the new material is machined into the final shape.

"It's essentially an automated process," Wold said. "You may have an operator hand loading parts into the machine, but you don't have multiple people hand-working parts."

On the downside, the capabilities of a hybrid machine tool don't come cheap. A Mitsui Seiki hybrid that can handle the impeller job will set purchasers back seven figures, according to Wold. However, he added, taking into account the high employee turnover rate that results when the job is done manually, the return on investment in a hybrid can take less than two years.

As for new builds, Okuma's Thiessen points out that a hybrid machine tool can be a good choice for manufacturing a part made of two different materials. Consider a part that is mostly stainless steel but includes a feature made of an exotic material like Inconel.

"Do you send that out to have it fabricated, or do you machine (the steel) and then put an additive Inconel portion on top of it?" Thiessen asked. "It very much would be a time advantage to be able to keep that in one machine. Even though it takes a little while to lay up the (Inconel), you don't have to take the part out of the machine and put it on a truck."

Then there's the fact that components that require an expensive material like Inconel in a certain area need not be made entirely of that material. "Say it's a 20" [508 mm] diameter part," Thiessen said. "If I can do a feature out of Inconel and the (main) body of the part can be a stainless steel or regular steel, I’ve saved myself a lot."

A hybrid machine tool can complete the additive process and then machine the added material to achieve the final shape and dimensions. Or if a part requires it, Thiessen said, a hybrid can go back and forth between additive and subtractive processes, adding some material and then machining the added material multiple times.

Okuma offers an additive option mainly with its multitasking lathe and five-axis vertical machining centers. To produce hybrid machine tools, the company has teamed up with Trumpf GmbH, which provides the additive technology. In Okuma's five-axis vertical hybrid, for example, a Trumpf laser head is mounted next to the spindle. "When you want to utilize it, a little doghouse opens up and the laser head comes out," Thiessen said.

The bad news for potential buyers is that the laser almost doubles the price of the machine tool, Thiessen cautioned. Therefore, he said, a hybrid "is not something you would just buy and see if you can find a use for it later."

In addition to advancing the technology inside their machine tools, suppliers are assisting customers interested in giving their machines a technological helping hand from the outside by automating their processes. While the onset of the pandemic triggered a lot of talk about industrial automation, it remains a hot topic in industry circles even as the threat of COVID recedes.

"With the lack of skilled machinists and engineers—and even the lack of unskilled labor—I think the level of automation is going to continue to grow exponentially," predicted Mitsui Seiki's Wold.

For machining operations, Wold said this means more than just automated loading and unloading of machines. "You could have a robot that is building tool assemblies, measuring tools and balancing them," he said, as well as a robot that is building fixtures and putting parts into them. "Then there's automation of how you transport tools, parts, and fixtures to the machine tool.

Just carting tools to and from the machine tool sounds like a pretty simple job, but I think in shops it's hard to find people to do that. But a simple robotic cart can be programmed to find its way through the shop to the correct machine tool."

Wold pointed out that the return on investment in this type of automation comes fairly quickly, but the upfront cost can be steep. He puts the cost of a basic system for loading pallets into a small machine tool at $50,000 to $75,000. For larger machines with very large pallet pools that are making expensive parts around the clock, he said, "I think you’re talking millions of dollars" in upfront automation costs.

On the other hand, he noted, "an employee doesn't really have an upfront cost. It's more of a cost that's recurring over time. So I think the challenge for a lot of companies is looking at the ROI (of automation) and not the upfront cost."

Mitsui Seiki doesn't make automation systems for its machines. With the firm focused on building machine tools, "we like to partner with companies that are specialists in automation," Wold said. "I think that works out better for the end user."

One machine tool builder that also makes automation equipment is Grob Systems Inc. in Bluffton, Ohio. Derek Schroeder, the company's sales manager for universal machines, sees machine tool automation becoming more flexible. Instead of systems capable of moving just one size pallet, for example, Schroeder said some automation manufacturers are turning out systems that can handle multiple pallet sizes, as well as cells that handle both pallets and workpieces.

An example of a more flexible type of automation is Grob's new PSS-T300. In addition to automatically removing and loading different size pallets, this tower pallet storage system can serve two different machines.

Another new automation offering from the supplier is the GRC-V vision robot cell, which is designed to pair a single Grob machine with a six-axis industrial Fanuc robot. As the name suggests, the cell is equipped with a vision system that allows it to find and load different parts in order to facilitate frequent part changeovers.

Typically, a robot cell is dedicated to a single part for a long period of time, Schroeder said. With the camera-equipped GRC-V however, "you could put in a different type of part every day or every shift and still have it robotically loaded."

Robot cells dedicated to a single part may also have grippers that are hard to adjust to accommodate different part sizes. In order to change over from a 10" [254 mm] wide part to one that's 16" [406 mm] wide, for instance, "someone would have to unbolt the gripper, move the fingers, and reteach the (positions) inside the cell," Schroeder said. "That changeover takes time and a pretty skilled person."

Therefore, Grob has also come out with an automatic gripper adjustment system. Instead of manually making the required changes to a gripper, Schroeder explained, a cell controller using this system brings the gripper to an adjustment stand inside the cell, where the fingers are automatically moved into the right positions to pick up a different size part.

Once it's up and running, of course, an automated process is easier on shop personnel than a manual one. But how easy is it to get to that point?

"I think there's a perception that robots are very difficult to deal with," Wold said. But good mechanical engineers who program CNC machines in shops won't find that to be the case, he insisted. "Once they get up to speed on a robot, they will tell you it is much easier than CAM programming a CNC."

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