Robots come in all shapes and sizes. But, some of the most popular machines feature six-axes of motion.

The versatile devices can approach a workpiece from any angle and can handle a wide variety of production tasks. That makes them ideal for applications that require complex motions, such as picking randomly oriented parts from a bin.

Six-axis robots can be mounted to a floor, a table, a wall, a ceiling or a linear actuator. They feature a high payload capacity, in addition to wide horizontal and vertical reach.

Traditionally, six-axis robots were not as fast and precise as Cartesian or SCARA robots. That’s why they were often relegated to dark corners of automotive plants, where they were primarily used for welding and painting applications. The machines were large, intimidating, stayed in one place, and worked behind safety curtains or fences.

Today, thanks to new technology, six-axis robots are starting to appear in a wide variety of industries, such as appliance, aerospace and electronics. And, they’re being deployed for a variety of assembly tasks, such as screwdriving and adhesive bonding.

The machines are now more affordable and easier to program than ever. As a result, even small manufacturers are investing in six-axis technology.

In some factories, the robots are starting to replace conveyors and forklifts. They are being piggybacked onto automated guide vehicles (AGVs) to extend their range. The mobile platforms can easily move around a plant floor and take robots wherever they’re needed.

Last year was record-breaking for the U.S. robotics industry. Demand grew by 10 percent over 2015 levels, sparked by a 61 percent increase in assembly applications and growing demand outside the auto industry.

“The use of robots is rising in small- and medium-sized companies that see robotics as a key factor in improving productivity and product quality to stay competitive,” says Jeff Burnstein, president of the Robotic Industries Association. “We expect these trends to continue well into the future.”

A New Generation

Today’s six-axis robots are quite different than what was available 10 or 15 years ago. The machines are less expensive and easier to use, and there are more options available than ever. They’re also more compact.

“Prices have come down dramatically in the last decade or so,” says Dean Elkins, senior general manager of sales at Yaskawa America Inc.’s Motoman Robotics division. “Robots today are about 25 percent less expensive than they were a decade ago. At the same time, programmability has become much easier. For instance, teach pendants are now much more intuitive.”

One of Motoman’s newest six-axis robots is the HC10, which features a speed- and force-limiting design that allows the machine to work safely in close proximity to humans.

“Utilizing easy guide-through teaching, it is fast to deploy or redeploy on demand,” notes Elkins. “The HC10 is easily adaptable to changing requirements, and can be integrated with existing automation infrastructure.”

The highly configurable machine offers a 10-kilogram payload and 1,200-millimeter reach. It can perform a broad range of material handling, machine tending or light assembly tasks.

“Robots are now quicker, more accurate, smaller and cheaper, with added reliability,” claims Nigel Smith, CEO of TM Robotics Inc., which markets Toshiba Machine’s line of products. “Compared to what used to be available in the past, the machines are now seen as more of a commodity rather than a luxury.”

Indeed, Smith says many manufacturers are no longer intimidated by six-axis robots.

“Today, they want robust, highly accurate robots that are suitable for high-speed assembly and material handling applications,” he points out. “They’re also looking to six-axis robots for increased dexterity.

“Manufacturers are trying to squeeze more and more functionality into a single cell, so the more flexible the robot is, the more likely it is able to help meet these demands,” says Smith. “Six-axis robots have more dexterity than traditional gantry-style machines.

“With more and more customers looking to install automation, the dexterity and flexibility of six-axis robots are solving a lot of issues and allowing for much higher efficiency across a wide range of industries, from automotive to medical,” explains Smith.

At the Automate show in Chicago earlier this month, Toshiba launched a new line of six-axis robots called the TVM series.

“It’s a cost-effective, energy-efficient, easy-to-program option for manufacturers,” says Smith. “This series is made for [manufacturers] that are looking for light-to-medium duty robots to perform tasks without being too cost prohibitive or sacrificing speed.”

Smaller Footprints

To meet performance and productivity objectives, more manufacturers are looking for easy-to-install robots with short cycle times that can be used in tight spaces, but are safe to operate with workers nearby. Thanks to new materials and new technology, dense robotic cells can now be designed to save on costly floor space.

“Six-axis robots have evolved significantly and are [now] very different than they were [in the past],” says Tobias Daniel, head of sales and marketing at Comau Robotics. “They are able to perform more tasks than in the past.

“This has required [robot suppliers] to increase performance, evolve the materials used to construct robots and modify the size of the [machines]. Today, alongside the large robots that occupy factories, we also find compact, small-sized six-axis machines built out of lightweight materials.”

Comau’s latest product, the Racer5, features an aluminum arm that can handle payloads up to 5 kilograms. The small robot was designed for high-speed assembly and pick-and-place applications in restricted spaces.

“Manufacturers continue to reduce the mass of robot arms to improve acceleration and speed of robots, while maintaining payload capacity,” explains Samir Patel, director of product and advanced engineering at Kawasaki Robotics USA Inc. “By optimizing arm design, the footprint of robots has decreased by as much as 40 percent.”

“Today, six-axis robots are compact in design, faster and more precise,” adds Phil Baratti, applications engineering manager at Epson Robots. “They are also using new drive technologies to manage higher payloads while maintaining rigidity.

“Features that we’ve added into all our products include a slimline design and added rotational capabilities of the pitch axis,” Baratti points out. “We have cut back the material on the robots in a way that allows additional rotation range on joints two, three and five, while maintaining the integrity in the structure of the arm.

“This allows customers to take advantage of an increase in overall working space by reducing the dead space closest to the base of the robot and allowing the arm to pull in closer between joints two and three, and joint five to joint four,” explains Baratti. “Every additional degree of motion helps in tight space applications.”

Epson engineers took that into consideration when developing the new Flexion N2 robot. Its compact arm has the unique ability to fold through itself vs. moving around itself. This reduces the number of intermediate points and shortens cycle times. As a result, the machine requires 40 percent less workspace area than standard six-axis robots. It boasts a 450-millimeter reach and 3-kilogram payload capacity.

“This patented folding arm technology has never been seen before in the automation industry,” claims Baratti. “Unlike any other six-axis robot on the market, the Flexion N2 features a unique tight space motion capability that keeps arm extremities out of the way, maximizing motion efficiency for faster cycle times.

“Applications that were previously unattainable, due to space restrictions, are now possible,” Baratti points out. “Several applications, specifically in the medical and electronics industries, require extreme precision and dexterity for handling small parts in a very tight environment.”

Another trend in six-axis robots is mobility. Some suppliers are merging robotic technology with AGVs.

“By attaching a robot to the back of an AGV, the machine becomes untethered,” says Yaskawa Motoman’s Elkins. “We consider it be an unanchored conveyor.

“This allows engineers to create an environment where the robot can service multiple machines, pick from multiple locations or perform multiple assembly operations at several workstations,” adds Elkins. “It helps free up floor space that might normally be obstructed by conveyors.”

Yaskawa Motoman recently launched the YMR12. It’s a combination of a Motoman MH12F robot, which features a 12-kilogram payload, and OTTO Motors’ OTTO 1500 self-driving vehicle, which boasts a 1,500-kilogram payload.

“This fully autonomous platform can perform multiple material handling operations and logistics tasks throughout [a plant] and can communicate with other machines via wireless direct connection to a PLC,” says Elkins. “The YMR12 is equipped with a vision system and an adaptive gripper. It provides a viable alternative to the traditional method of utilizing a fixed robot station.”

Human-Robot Collaboration

Collaborative robots are the hottest trend in the automation industry. In fact, the technology dominated the exhibit hall and educational sessions at the recent Automate show in Chicago.

Next-generation machines equipped with state-of-the-art sensor technology allow robots to operate side-by-side with humans. Unlike traditional six-axis robots, collaborative machines are lightweight, flexible and can easily be moved and reprogrammed to solve new tasks. They require little or no safety barriers, which consume valuable bench and floor space, obstruct access to equipment and reduce productivity.

One manufacturer that is harnessing the power of collaborative robots is Whirlpool Corp. Several of its U.S. plants have added the machines to their assembly lines. They are used for repetitive tasks, as well as applications that require precision, such as applying the same amount of glue in an exact location.

Whirlpool is using six-axis robotic arms supplied by Universal Robots.

“Collaborative robots allow us to be much more flexible,” says Eric Howe, senior engineer and automation lead. “Because they’re fairly small and lightweight, they can easily be moved, if needed. They also are easier to program than traditional robots, which saves time. And, they’re relatively inexpensive when compared to other technologies.

“The addition of the robots allows our employees to focus on tasks that require greater cognitive skill,” adds Howe. “We’re developing a user interface in-house so that we can be flexible and self-sufficient as we continue our implementation.”

Another manufacturer that has successfully deployed collaborative robots on its assembly lines is BMW. At the automaker’s plant in Leipzig, Germany, a lightweight robot interacts closely with human assemblers. It dispenses adhesive along the edge of windshields. Safety sensors monitor the functions at all times and stop the process immediately if an obstacle is detected.

“[Collaborative robots] are becoming more common in areas [where robots traditionally worked] behind safety fences,” says Christian Dunckern, head of production planning, toolmaking and plant engineering at BMW. “Their flexibility, modest space requirements and high level of safety grant people access to areas that used to be off limits.

“Thanks to the broad range of possible applications, lightweight robots open up new potentials in the field of traditional automation and give [engineers] more leeway to implement improvements,” adds Dunckern.

Intelligent control systems, plus advances in computing power and safety systems, have made human-robot collaboration a reality.

“It used to be that robots were [only] employed in what we called dumb, dirty and dangerous tasks, sparing humans from the drudgery of performing these types of operations,” says Paul Deady, North American automotive segment manager at Stäubli Robotics. “Today, the ability to utilize advanced sensors to understand what’s happening around a robot and cause the robot to respond appropriately, and with absolute safety, is a tremendous advance to the state of the art in robotics controls.”

At the recent Automate show, Stäubli unveiled its TX2 line of six-axis robots and its CS9 controller. The robots are available in six different models that can handle loads between 2 and 15 kilograms, with a reach between 515 and 1,450 millimeters.

“With the launch of the TX2 series and CS9 safety control, Stäubli has opened a new chapter in man-robot collaboration,” claims Deady. “The robots have a separate safe digital encoder for each axis and an integrated safety board. All safety features comply with the stringent requirements of the highest safety category, SIL3/PLe.”

To ensure maximum safety, every movement of the robot is monitored by sensors. In addition, all the coordinates of the robot, as well as its speed and acceleration, are recorded in real time.

“Generally speaking, robots are either purpose-built for speed and precision, but must be caged up away from people, or they are built to safely work around people, but they compromise speed and precision,” says Deady. “With our new robots, there is no need to make that choice. 

“What is unique about [our] offering is the ability for the same robot to operate in a mode that makes it safe to work around people, or in a full production mode,” explains Deady. “[Manufacturers] have the ability to dynamically switch between these two modes as appropriate, using sensors to understand what is going on around the robot.”

Large and Small Extremes

Six-axis robots are also growing larger and smaller. At one extreme, there are massive machines that can lift extra heavy payloads. On the other end of the spectrum, tiny tabletop units can carry out many of the same functions as their big siblings.

Mega material handling robots are ideal for moving automobile, tractor and truck frames, boat hulls and heavy aerospace structures. They eliminate the need for overhead gantry cranes and hoists.

A heavyweight battle for the title of world’s largest and strongest robot is currently being waged by ABB, Fanuc and Kawasaki.

ABB’s IRB 8700 has a reach of 3.5 meters and can handle payloads of up to 800 kilograms. Fanuc’s M-2000iA/1700L can lift objects that weigh up to 2,300 kilograms, with a reach of 4.6 meters. Meanwhile, Kawasaki’s MG15HL can accommodate payloads up to 1,500 kilograms. It boasts a 4 meter horizontal and vertical reach.

The IRB 8700 made its North American debut at the recent Automate show. It wowed attendees by carrying four 70-inch video screens and a 50-inch projector with interactive displays. The powerful machine was equipped with ABB’s SafeMove2 robot monitoring software.

“The IRB 8700 is intended for palletizing applications and for moving car bodies around auto plants,” says Nicolas De Keijser, assembly and test business line manager at ABB Robotics. “The robot automatically adapts and adjusts its speed to accommodate heavy and wide parts.

“It only has one motor and one gear per axis, while most other robots in this size class use dual motors and gears,” adds De Keijser. “Fewer components and shorter cycle times make the machine 25 percent faster than any comparable robots in its payload range.”

One of the most intriguing machines on display at Chicago’s McCormick Place earlier this month was not a big behemoth. Instead, it was the Meca 500 from a Canadian startup called Mecademic Inc., which claims that it makes the world’s smallest six-axis robot.

The benchtop unit weighs less than 5 kilograms, has a payload capacity of 0.5 kilogram and boasts a repeatability of 0.005 millimeter. Potential assembly applications include electronics, medical devices and watchmaking.

“It is not only twice as small as any other small industrial robot arm, but has no bulky controller cabinet and no thick tangling cables,” says Ilian Bonev, Ph.D., director of the Control and Robotics Laboratory at l’Ecole de Technologie Superieure (ETS) in Montreal and co-founder of Mecademic. “Its controller is fully embedded in its palm-sized base.

“Unlike virtually all other industrial robots, we’ve designed our [machine] as a component, rather than as a complex standalone system,” notes Bonev. “We’ve also designed a very simple communication protocol with less than 50 proprietary commands.

“We’re addressing a growing demand for precise, delicate manipulation of small parts in confined spaces,” claims Bonev. “Products are getting smaller and need to respect close tolerances. Factories lack space and need to be more energy efficient.

“We thus enable a whole new range of applications, products and discoveries that were nearly impossible before,” says Bonev. “Most of our customers simply couldn’t perform their task before because of lack of space.”