As error proofing, quality control and flexibility become essential on today’s assembly lines, more manufacturing engineers are going electric. State-of-the-art tools allow engineers to adjust tool speed to match various applications and control more aspects of the fastening process, including key parameters such as torque and angle.

“The initial cost [may be] a shock,” says John Hodge, product specialist at Stanley Assembly Technologies. “But, the total cost of ownership [is an important factor to consider] due to the minimal maintenance [required compared with air tools] over the life of the tool.

“The most popular feature is error-proofing capabilities, due to the feedback you get from DC electric tools,” Hodge points out. “Younger engineers are more datacentric than older engineers and only DC electric tools can provide that.

“Fasteners are getting smaller and more engineered, so the typical ‘tighten to torque’ [mindset] doesn’t work anymore,” adds Hodge. “Because DC electric tools can be controlled in many ways, they are becoming [popular] on the plant floor due to the fastening strategies that can be employed to secure these new fasteners.”

Many manufacturers are using DC electric systems to improve their overall assembly process. With the global push toward improving quality control and reducing warranty costs, many companies have implemented lean manufacturing principles, such as poka yoke, to stay competitive in the marketplace.

“Manufacturers are implementing DC electric [tools] as one more piece of the quality equation,” claims Tom Hutchens, divisional sales manager at AIMCO. “Accuracy, flexibility and networking capabilities make DC electric systems a perfect fit for manufacturers to invest capital and show positive ROI.”

“Only DC electric tools offer the accuracy, control and process security necessary for safety-critical, function-critical and quality-critical applications,” adds Dan Cejka, product manager for tightening and welding systems at Bosch Rexroth Corp. “Other types of tools cannot provide the accuracy and feedback required for these types of assemblies.

“Process feedback and torque verification is critical to many customers,” explains Cejka. “DC electric tools [can] handle complex applications, such as thread forming or tapping, which can’t be done with mechanical clutch tools. They also can fasten multiple bolt assemblies in a single pass by synchronizing tightening to achieve an even clamp load, improving both product quality and throughput.”

“Today’s demand for quality with a highly accurate and repeatable fastening [process] is the main reason why customers start looking to electric tools,” notes Paul Gomez, director of engineering at FEC Automation Systems. “A multitude of fastening parameters [can be] programmed and selected for multiple models being run on the same assembly line. And, [engineers can] collect and store data from each fastener [used in the assembly] operation.”

According to Gomez, the No. 1 reason why manufacturers buy DC electric tools is to improve the accuracy of their fastening applications. “They have a fastener that needs to be torqued to a given specification and they need the confidence that the torquing operation [will be] performed each and every cycle within those specifications,” he explains.

Electric tools offer more accurate torque, repeatability, traceability and dependability than air-powered alternatives. “There are many capabilities not offered with conventional assembly tools,” claims Mike Scott, sales manager at ASG Precision Fastening Product Group. “There are multiple torque control strategies available, including simple ratcheting clutches, shut-off clutches with electronic dynamic braking, and closed-loop torque and angle control.

“This provides excellent torque control possibilities,” adds Scott. “Also, there are various choices for input-output, [ranging] from simple complete output signals to complete torque-, angle-, time- and date-stamped data through shop-wide networks.

Scott says his company plans to release a higher torque DC-transducerized system with “extreme enhancements in ergonomic technology through pulse fastening. Pulse fastening technology significantly reduces the torque reaction experienced in the fastening process, while maintaining torque accuracy.”

Green manufacturing is another trend that’s making DC electric screwdrivers and nutrunners more appealing to engineers today. “With [more] manufacturers looking for greener technology, more of them are turning to electric technology every day,” says Russ Hughes, product marketing specialist at Desoutter Industrial Tools. “Electric tools have several advantages over pneumatic tools. [For instance, they are less expensive] to operate. [They also] leave a smaller CO₂ foot print on the environment.”

Diverse Applications

Electric screwdrivers and nutrunners are used in many industries. The technology is popular in the automotive sector, due to high production volumes and the large number of fasteners used on assembly lines.

According to Hutchens, 70 percent to 80 percent of automakers and Tier 1 suppliers have already converted to DC electric fastening systems. “However, many other [industries] have invested in the technology, including aerospace, medical, heavy agriculture, appliance and energy,” he points out.

“Anyone using threaded fasteners [benefits from DC electric tools],”  claims Mark Hasz, assembly tool marketing manager at Ingersoll Rand. “The bulk of the volume is [still in] automotive manufacturing, but we’re now seeing the same focus on quality control in appliance, electronics, farm and construction equipment, and many general assembly applications.”

In these industries, there’s a move to expand the use of DC electric tools from applications with a few critical joints—such as the hinge on a refrigerator door or the retaining bolts on a washing machine drum—to more general applications with a move toward total process control.

“Automotive manufacturers were the first to realize the potential DC electric tools [can have on improving] the quality of their products,” adds Hughes. “From this, it trickled down to the tier suppliers as a mandate to prove the quality of the product with the needed traceability demand from their customers.”

Hughes says household appliance manufacturers are using DC electric tools today to assemble everything from radios and refrigerators to hot water tanks and electric meters. “All [this activity is] an effort to increase the quality of their products and increase their error-proofing capabilities over pneumatic tools,” he explains.

“Off-road equipment manufacturers also have [adopted] DC electric tools to help with their error-proofing,” Hughes points out. “And, aerospace manufacturers are turning to [the technology] every day.”

Desoutter recently introduced a cordless tool called Bflex, which was designed specifically for off-road and aerospace assembly applications. The standalone tool does not require a controller. Operating parameters are stored directly on the tool. It stores results and graphs for exporting at a later time.

Bosch Rexroth has also developed wireless fastening tools. Its new Nexo line incorporates the entire controller onboard the tool. “This provides the control and process security of a DC tool without the restriction of cable or need to maintain connection to an external controller,” says Cejka. “[Because of the] integrated controller and color HMI [the tools can operate] in wireless deadspots or shielded areas without loss of functionality.”

What’s New

Manufacturing engineers have a wide variety of DC electric tool options to choose from today, including both corded and cordless models. The tools are lighter, faster, smaller and smarter than what was available a decade ago. In addition, state-of-the-art software makes it easier to connect with plant-floor networks and integrate the tools with quality and error-proofing systems.

The biggest trend in DC electric technology is cordless tools. “The battery technology needed to effectively drive the motors didn’t exist 10 years ago,” says Hughes. “Today, with lithium-ion batteries, we are able to run faster and last longer on a single charge, making DC electric cordless tools a reality.”

According to Hasz, cordless tools allow assemblers easy access when working inside vehicles. “This helps eliminate safety and quality issues resulting from cords getting snagged on moving assembly lines or parts,” he points out. “It also reduces maintenance costs—the cord is the most frequently replaced part.”

Ingersoll Rand recently unveiled its QX Series of pistol tools. They feature a closed-loop transducer system that can operate either independently or in unison with the plant control system via a wireless system.

The QX tools produce between 0 .8 and 12 newton-meters of torque and can store up to 1,200 fastening cycles on board. They are powered a 20-volt lithium-ion battery.

“The software on the tool allows the operator or the plant control system to select any of the eight configurations that are user programmable,” says Hasz. “Key items that are programmed are target torque; torque upper and lower limits; free speed; shift down speed; angle; and direction of fastening. Three different fastening strategies are selectable: torque, angle and prevailing torque, along with the ability to have multiple steps and gang count.”

Many state-of-the-art DC electric tools are much easier to integrate into an assembly line than in the past, thanks to options that allow manufacturers to choose

their own fieldbus technology. “Controllers are now much more flexible, with built-in learning modes to help the operator optimize the tool for a specific joint,” says Hughes. “[That helps] keep things simple in the transition from pneumatic tools to DC electric.”

“Today’s technology provides the opportunity to verify, track and store fastening results, which [provides a history of the assembly process],” adds Gomez. “The size and speed of the tools [is also different, which allows them] to adapt easily to flexible and lean assembly processes. [And the smaller] size of the tool controllers reduces plant floor space.”

FEC Automation Systems plans to unveil a new multispindle DC electric fastening system later this year. The controller hardware is the same platform across three product lines—a multispindle nutrunner, a hand tool nutrunner and a servo press.

“It will incorporate the function that was once a separate ‘master’ or ‘multi’ controller into the spindle controller, eliminating the need for it,” says Gomez. “The controllers will power smaller, higher-speed multispindle tools.”

Many engineers are demanding that controllers take on more integration work and make the fastening process more streamlined. “Tools and controllers are asked to include bar code scanners and have wireless power and wireless communications to control the data collection systems,” notes Hodge. “[Many manufacturers] now have a ‘plan.’ [They’re] looking at spare parts, commonality and how each tool will fit into the bigger plant integration scheme.”

Stanley Assembly Technologies recently unveiled its QPM EB line of tools. “This refreshes the old standby QPM E family of tools we had,” says Hodge. “We updated the motor [so that it’s faster and more efficient] and added new gearing to match the faster motor. [We also] created a new angle head to fill a gap in the sizes we offered and added a redundant transducer to the fixtured tools.” The tools were also redesigned to work with new controllers.

“On the controller side, you see many of the same feature sets offered years ago, but now [available with] additional benefits related to plug-and-play strategies and multisystem integration,” adds Hutchens. “The user interface has become similar to smart phones and notebook computers, so set up time is easier and uptime on the assembly floor is improved.”

 AIMCO’s newest DC electric tool offering is its Acradyne HT Series. “It combines the feature sets of our existing DC systems for critical high-torque applications,” Hutchens points out. “The transducer torque control system provides consistent, reliable torque values, as well as the ability to control or monitor rotational angle during the tightening process.”