Robotics and Energy Cost Reduction
| By: Bennett Brumson, Contributing Editor
With the price of fossil fuels at historic highs, reducing the cost of the energy component of production is on the mind of manufacturers all over the globe. There are several strategies to meet this challenge. One proven method is to deploy robotics.
‘‘Robots with servo motors are already very efficient relative to power usage. Today’s AC servo-controlled robots use far less power than the DC servo-controlled robots of years ago,’‘ says Chris Anderson, Welding Technology Leader at Motoman Inc., a robot manufacturer and systems integrator headquartered in West Carrollton, Ohio.
Lights Out, Nobody Home
Because robots can operate unsupervised, they can produce items while people are not present. The ability to operate in the dark or in unheated environments can lead to substantial energy savings on the part of manufacturers.
‘‘If factories use robots, they can have lights out facilities,’‘ asserts Dick Johnson, General Manager of the material handling segment at FANUC Robotics America, Inc., Rochester Hills, Michigan. Johnson adds that robots can help save money on energy costs by decreasing the need to heat and cool a factory. ‘‘Robots are designed to work across a wide variety of temperature ranges, and are less fragile than human operators. There is less of a need to cool or warm a production plant,’‘ Johnson says.
Likewise, David Arceneaux, Business Development and Marketing Manager at Stäubli Robotics, Duncan, South Carolina, says robots require fewer utilities to perform their functions. ‘‘Robot can operate in dark environments, so there is no need for overhead lighting in fully automated work cells. If the same operation was done manually, there would be a need for overhead lighting and other facilities.’‘
Arceneaux’s colleague at Stäubli, James Cook, agrees. Cook, an applications engineer at Stäubli, says robots can help lower building costs by providing for smaller work cells. ‘‘Manufacturers can fit a larger number of compact cells in the same space to increase production without adding heating, lighting or cooling to the cost of the building,’‘ Cook says.
Saving money on utilities is also a concern for John Kowal, Global Marketing Manager at, ELAU Inc., Schaumburg, Illinois. ELAU is a specialist in packaging robotics. ‘‘Floor space is a measure of energy usage because that floor space has to be heated, cooled and lighted. The more that can be produced in a small space, the less the building will cost. Lowering energy costs can be done through the use of compact robotics,’‘ Kowal says.
FANUC Robotics’ Dick Johnson also says that robot controllers can help lower the energy bottom line by turning off peripherals when they are not needed. ‘‘Controllers can shut off motors, machine tool coolant pumps, and spindles. This will reduce energy usage significantly over time. A person might or might not remember to shut off a machine during lunch or breaks, but if a robot is programmed to do that, it always will.’‘
The ability of the robot controller to manage all aspects of the work cell makes way for more efficient use of energy. Michael Calardo, Vice President for Product Management at ABB Inc. speaks on the role robotic controllers have in lowering energy costs. ABB is a robot manufacturer and systems integrator located in Auburn Hills, Michigan.
‘‘Robots have improved control of motion, so there is a lot of energy savings because acceleration and deceleration are done in a much more controlled way,’‘ Calardo says. Calardo adds that this improvement comes from more sophisticated algorithms in control technology.
Calardo went on to say that the change to direct current control of weld guns from standard 60 cycle alternating current is a source of energy saving in robotic work cells. ‘‘Direct current weld guns run at 1,000 Hertz instead of 60 Hertz. This reduces the size of transformers and the size of cables used, which is less weight the robot arm has to carry,’‘ Calardo says. A lighter-weight robot arm translates into less energy used and a higher payload capacity.
Another innovation that helps robotic systems use less energy stems from the change to field bus I/O systems from 110 volt relays. ‘‘Field bus I/O systems use 24 volts rather than 110 volts, which makes for more energy efficient devices because they are not powering a lot of relay coils,’‘ Calardo says. Relay coils waste energy in the form of heat loss.
Depending on the application being integrated, robots can reduce the energy cost of production.
‘‘Robots are very energy efficient. The energy cost to run a robot can be less than a dollar a day, depending on the application,’‘ Motoman’s Chris Anderson says. Randy Schuetz, the coating technology leader at Motoman, maintains that robotic painting calls for less energy use than that of manual painting or even that of fixed painting automation systems.
‘‘There are reduced exhaust air and make-up air requirements for robotic spray booths. A typical
manual spray booth requires an airflow velocity of 100 feet per minute whereas less than 60 feet per minute is required by robotic equipment.’‘ The equipment that provides air flow to robotic paint booths needs to deliver less than 60 percent of that air, so less energy is required to perform its task.
Schuetz adds that robotic painting lends itself to reduced fluid flow requirements, so it is more energy efficient in delivering the paint over manually applied paint. ‘‘Robotic spray equipment typically achieves higher transfer efficiency versus manual spray equipment and reduced paint usage. Higher paint usage requires more energy for temperature control for proper paint circulation,’‘ Schuetz says.
Material handling is another application where robots could assist in achieving energy cost savings. Dick Johnson of FANUC Robotics speaks of this. ‘‘Large payload material handling saves the most energy. FANUC Robotics installed a robotic system replacing fixed automation that was hydraulically controlled. An electric robot, when not moving, shuts itself off, so very little energy is being used,’‘ Johnson says. Johnson went on to explain that the original equipment had a standard hydraulic pump that pressurized fluid to perform work.
‘‘When the system is not working, the fluid is dumped over a pressure relief valve which caused the fluid to heat. There is a chiller that cools that hydraulic fluid. One can argue that the system used more energy when not working than when it was working,’‘ Johnson says.
Spot welding is another energy-intensive application where robotics could help to bring energy cost under control. It is primarily due to the increased use of servo controlled weld guns over relatively inefficient pneumatic weld guns.
‘‘I see the greatest efficiency gains in spot welding not only because of much more efficient robots but also more efficient weld controllers. ABB uses servo spot welding guns rather than pneumatic spot welding guns,’‘ says Michael Calardo of ABB.
End effectors are a significant element within work cells and the energy they consume is not trivial. To lower energy costs, a good place to do that is through end effectors.
Andy Lovell, application engineer at PIAB Vacuum Products, Hingham, Massachusetts, an end-of-arm-tooling provider, addresses energy efficient end effectors. ‘‘If designers can build an end effector to do the work required of it and can make it light weight and as simple as possible, that translates back to the robot becoming lighter in weight and easier to maneuver,’‘ Lovell says.
Systems integrators have to take into account the mass of the product being produced as well as the mass of the end effector handling the product. ‘‘Having a small, light weight end effector impacts the size and the complexity of the robot. Smaller and lighter robots save energy through down-sizing,’‘ Lovell adds. Using appropriate sized equipment saves weight, thus saving a lot of energy over time.
Dick Johnson of FANUC Robotics compares hydraulic end effectors with those that are servo controlled. ‘‘Hydraulic end effectors are not used much anymore. There is an increase in the use of servo end effectors because they are the most efficient’‘ Johnson says. ‘‘A servo controlled end effector uses energy while it is turning. When the servo stops turning, the end effector can hold the product but not expend any energy.’‘
Johnson continues by recalling a work cell that used vacuum as a power source for end effectors. ‘‘One approach is to drive a vacuum motor that is placed near the robot’s base. In one work cell, FANUC Robotics had a palletizing robot using a vacuum plenum that picked up and palletized bags of product. It was relatively energy inefficient.’‘
Johnson explains the more energy efficient alternative system. ‘‘We replaced the plenum with a fork gripper that was powered by air cylinders. This is much more energy efficient,’‘ Johnson says. ‘‘Throughput increased from twelve bags per minute to 28 bags. This is a win-win arrangement, from both an energy point of view and throughput.’‘
Johnson adds that the vacuum-powered plenum system could hold the bag, but not firmly enough to convey it at high speeds. With forks, the bags were securely grabbed.
Waste Down, Productivity Up
Robots are the perfect solution to reduce both material waste and energy use simultaneously. James Cook of Stäubli connects the use of robotics with the reduction of wasted material and reduced energy.
‘‘Robots waste much less material than manual production or hard automation. A robotics painting system uses the same amount of paint for each part, greatly reduces over-spray, and eliminates the need for touch ups,’‘ Cook says. ‘‘Robots used for assembly or material handling always repeat the process exactly, reducing or eliminating defective parts,’‘ adds Cook. The same is true for welding and dispensing applications.
Hard automation equipment sitting idle or having to rework parts waste both material and energy. All applications can benefit from the use of robotics. The savings of energy and the reduction of waste increase throughput, efficiency and profit.
In the foreseeable future, the price of fossil fuels will most likely stay at the current historical highs or even climb further. Now is the time for manufacturers to consider strategies to produce their product while still making a profit. Smart companies will examine flexible robotics as part of that strategy. The robotics industry will meet that demand by making their products better, lighter, and faster. ABB’s Michael Calardo sees the robotics industry doing just that.
‘‘I see lighter weight smaller, and, trimmer robotic arms while increasing payload. Our goal is to improve that ratio,’‘ Calardo says. ‘‘The more the ratio between the arm’s weight and its payload can be improved, the more energy efficient the robot is.’‘ That improved ratio of a less dense but stiffer robotic arm combined with advances in control algorithms, will lead to even greater energy efficiency through robotics.
Editor’s Note – Editor’s note - For more information, you may contact any of the experts listed in this article or visit Robotics Online, Tech Papers.
-Chris Anderson, Motoman Inc., 937/847-6200, [email protected]
-Dick Johnson, FANUC Robotics America, Inc, 248/377-7678, [email protected]
-David Arceneaux, Stäubli Robotics, 864/486-5416, [email protected]
-James Cook, Stäubli Robotics, 864/433-1980, [email protected]
-John Kowal, ELAU Inc., 847/490-4270, [email protected]
-Michael Calardo, ABB Inc., 248/391-8478, [email protected]
-Andy Lovell, PIAB Vacuum Products, 800/321-7422, [email protected]