Peter Zelinski has been a writer and editor for Modern Machine Shop for more than a decade. One of the aspects of this work that he enjoys the most is visiting machining facilities to learn about the manufacturing technology, systems and strategies they have adopted, and the successes they’ve realized as a result. Pete earned his degree in mechanical engineering from the University of Cincinnati, and he first learned about machining by running and programming machine tools in a metalworking laboratory within GE Aircraft Engines. Follow Pete on Twitter at Z_Axis_MMS.
Toolholder, tool and retention knob are all shipped as an assembled, pre-balanced unit that is tailored to the dynamics of the user’s particular Okuma machining center, allowing that machine to achieve something near to the smoothest and most productive possible milling available to it. The placement of a custom setscrew slot in the tool ensures the proper tool overhang length for this dynamic optimization.
Every milling process has a spindle speed, or a set of spindle speeds, at which it inherently wants to cut. Run at one of these particular speeds—often known as the “sweet spot”—and chatter will quiet down. Thus, heavier cuts become possible and higher tool life is achieved.
But here is the problem: Those seemingly magical spindle rpm values are different for every different combination of machine, toolholder, cutting tool and tool overhang length. Finding the right speed for every important combination can take a lot of either test cutting or “tap tests” (vibration measurement) to identify the particular dynamics of each machining combination. Then, keeping track of all those combinations so that the right speed is programmed for the right setup can be just as difficult.
At IMTS, Velocity Products will debut a solution to this problem. Within Okuma’s booth at the show, the company is exhibiting its new “Smart Tool” system—a custom combination of tool and toolholder, with tool overhang length controlled by the positioning of a custom set-screw slot in the tool, all optimized for the end user’s particular machining center. The system even comes with BlueSwarf Tool Dashboard software for quickly finding the spindle speed, feed rate and depth of cut delivering the optimal performance for this combination of machine and tooling within a given material.
Each Smart Tool assembly also comes with a BlueSwarf Tool Dashboard, allowing the user to quickly find the combination of cutting parameters delivering optimal performance with that particular tool setup.
Velocity is the company marketing the Smart Tool system, but it could not have achieved it alone. The promise of delivering “sweet spot” milling as an out-of-the-box product in this way is actually the result of four different companies working together. The other three are milling dynamics specialist BlueSwarf, toolholder manufacturer Briney Tooling Systems and cutting tool maker Fullerton Tool Co. (Briney and Fullerton will be exhibiting the system in their IMTS booths as well.)
And one other company significant to the product is Okuma. Importantly, the Smart Tool system is available only for Okuma machining centers. Providing optimized tooling packages for every major machining center model would have been an impossibly vast challenge. Instead, the partner companies’ connection to Okuma made it possible to create a solution that serves the many users of this company’s set of machines. Velocity is part of the Morris Group, an Okuma distributor, and BlueSwarf is part of Okuma’s “Partners in THINC” network, which opened the way for sufficient access to the company’s machine tools to be able to measure their dynamic properties and begin to mathematically model optimal tool-toolholder combinations for the various machines in this family.
Now, Smart Tool users on Okuma machines will be able to mill at smooth-cutting sweet spots without performing any vibration measurements of their own. Because machine tool users routinely get by without running at these sweet spots, the Smart Tool partners say that a doubling of tool life and metal removal rate is a realistic outcome once the shop begins to use a tool assembly that has been dynamically tuned to its machine.
When the tool in the system wears out, it is reordered from Velocity. A unique order number identifies the user’s particular Smart Tool assembly. Velocity coordinates with Fullerton, which manufactures the tool with the setscrew slot in the right location for the necessary overhang length for that assembly. The custom-tuned product is thus delivered as if it were an off-the-shelf item.
Indeed, the manufacturing of that tool is liable to be close to many of its users. The same is true for the toolholder, because both Fullerton and Briney perform their manufacturing in Michigan. Therefore, there is this one other sense in which the Smart Tool system is optimized to the concerns of many users, the companies say: The entire system is made in the U.S.
A machine such as this one, which combines additive manufacturing with subtractive machining through five axes of motion, can be controlled using today’s existing CNC technology.
So-called “hybrid” machine tools, which combine additive manufacturing with CNC machining, might prove to be the most effective way for many manufacturers to implement additive manufacturing. The adoption and development of these machines is liable to advance. But even so, CNC technology will not have to race to keep up, says Randy Pearson, international business development manager for Siemens. He points out that existing, standard CNCs have been implemented on hybrid machines today. This level of control technology is up to the task of running the multi-process machines, he says.
Indeed, more challenging unions have already been achieved. Siemens has demonstrated a machine tool and robot under the coordinated control of a single CNC. Part of the challenge in this is that the robot and machine tool obey different command languages. Uniting metal cutting with additive manufacturing does not feature this challenge, he says, because the additive process uses just a modified set of codes within the language of the machine tool. Seen in this light, additive is a natural function for the machine tool to take on, and the control is ready for this addition.
Pearson says, “Whether the parameters involve laser gases, powdered metal deposition and inert atmosphere vacuum or five-axis rotation of a milling head or rotary table, the function of the control remains nearly identical. In this way, a single control can run two varying technologies for fabrication and chip cutting, either on a single channel or on a two-channel unit.”
Additive manfuacturing can make a part as if from nothing. Without tooling and without a pattern, the machine can generate a precise, solid, intricate form. But is “nothing” really the best starting point?
DM3D, a Michigan-based manufacturer of production AM parts, has recently been advancing a different idea. In some cases, rather than using AM to grow the complete part, the far more efficient use of additive is to start with a basic workpiece and grow the necessary details onto this part. “TransFormAM” is the company’s brand name for this idea.
The part above provides an illustration. This 25-inch diameter Inconel 625 component represents a jet engine casing. For a part like this to be grown entirely through AM would take something like 500 hours, says DM3D. An alternative is to begin with a cylindrical blank of material produced through forging or roll forming. When the company made the part this way, using AM just to add features and details, the additive cycle time was only 21 hours.
Automation is a broad topic that we often picture narrowly. Say “automation,” and we tend to picture robots—even though the range of what automation might involve includes these devices and more. Similarly, we tend to imagine that automation refers to technology taking the place of people. In fact, productive uses of automation in manufacturing often involve people and technology working in parallel to complement one another. I had a chance to talk about automation—its importance, its value, and why it is succeeding now—in this video.
A collaborative robot (green) ran alongside a demonstration of a fenceless robot at the automation integrator’s event. A fenceless robot uses sensors to halt the robot’s operation if a person comes too close.
One of the most significant recent developments in industrial robotics is the commercial introduction of collaborative robots. A collaborative robot (sometimes shortened to “cobot”) is a force-limited, contact-sensing robot that is safe to apply in the near and immediate presence of a human being, without guarding, because the robot will stop if it contacts a person and it will not move with enough energy to injure a person if it does make contact.
Last week, robotics integrator Acieta hosted a day-long event at its Council Bluffs, Iowa, headquarters focused on collaborative robots. Speakers represented not just Acieta but also ATI Industrial Automation, FANUC America, Schunk, Distefano Tool & Manufacturing Co. and the Robotics Industry Association.
Acieta founder John Burg described to me why it was important for the company to host this event: Manufacturers are rightly impressed with the possibilities of collaborative robots, he says, and many engineers are being urged by their management to explore a collaborative automation solution. Yet many of those applications simply do not lend themselves to a robot of this type.
Here is a recent example of an application he has seen in which a collaborative robot makes sense: A basket that is sent into heat treatment is manually loaded with parts. Various baskets have warped differently after many heat-treat cycles, so automated loading of the baskets is problematic. However, a robot lifts the basket of parts once it is full. Here, collaborative technology makes it safe and simple for a person and a robot to work on the task together.
But in a different application in which the user was initially focused on a collaborative robot, Mr. Burg says this user needed to achieve a narrow cycle time target for the productivity of the robot loading. Part of the way collaborative robots protect against injury is by moving slower than other robots have the capability of doing. And as it happened, this limited speed proved too slow to meet the needs of that application.
A presentation at the event by Schunk Regional Sales Manager Larry Bergren gave attention to another straightforward consideration relevant to collaborative robots. Namely, the gripper is not necessarily collaborative. A standard robot gripper does not offer the same responsiveness to contact that the robot itself does, he says.
Schunk has such a gripper under development and plans to introduce it soon, but the product is not ready for market yet. For now, he says, the company will offer a selection of grippers to complement collaborative robots. Grippers in this category can limit grip force, are covered in soft material and designed to limit sharp edges and pinch points, and feature a light indicating when the gripper is about to move. All of these features enable safe use near humans until the fully collaborative gripper comes.
In a different presentation, Claude Dinsmoor, general manager for material handling segment robotics with FANUC America, described some of the background of collaborative robotics as well as his view of a possible future.
This type of robot became viable for widespread industrial application in part because of an ISO standard, he says. A standard related to the safe application of industrial robots was revised in 2012 to address power- and force-limited robots. Guidance added later addressed the maximum force that different parts of the human body could acceptably experience in a contact with a moving robot. Those parameters enabled the development and introduction of robots that could be assured of not causing injury in moving contact. The result is a robot operating under very different rules than conventional robots, he says, because the latter are almost always kept segregated from humans. To note the difference, FANUC departed from its trademark yellow color in order to make its collaborative robots green.
A factor he noted is the planning this robot might create the need for, specifically because of the breadth of interaction it might have with people. The robot itself is safe to operate near a person, but how many people in the organization will have access to it? In a wide-open cell, any employee walking through the shop might step close to the robot. The entire environment this robot figures into potentially has to be evaluated for safety with this possibility in mind.
Indeed, that consideration is partly why achieving unguarded safety through collaborative robots might ultimately prove to be simply an interim step, he says. Today, a robot limited in speed and payload presents the most effective option for using robots near people. But another option already in use involves applying sensors to allow regular robots to be “fenceless.” The robot controlled in this way will slow when a person comes near, and it will stop when a person comes very close. In the future, continued advances in sensing technology might lead to even more effective fenceless robots that are safely capable of fast and highly productive use near people.
Collaborative robots are force-sensing robots that are safe to operate near people. These machines ran in unguarded demonstrations at the Acieta event focused on this technology.