Anybody tasked with equipping an assembly line with torque electric screwdrivers will run into a few different technologies while researching their options. These include clutch screwdrivers, current-controlled screwdrivers and transducer screwdrivers.
Selecting the appropriate type of electric screwdriver depends on a variety of factors: budget, precision requirements, complexity of the assembly job, as well as any clean-room and safety regulations.
Clutch-controlled electric screwdrivers
The simplest and most cost-effective tools in the market tend to be clutch-based. Common in the electronic industry, these tools use a clutch to control the amount of torque that’s applied to a fastener.
These tools are very easy to install, operate and maintain. Torque is set near the front of the screwdriver and, during the fastening operation, once the pre-set torque is achieved, the clutch disengages the electric motor.
Clutch screwdrivers like Kolver’s RAF & FAB series (and the brushless KBL series for those seeking maintenance-free screwdrivers) are an excellent choice for high-volume applications in the 0.4 - 44.5 lbf-in range that require ESD compliance, excellent ergonomics & reliability and a quieter and pollutant-free work environment.
Clutch screwdrivers do require somewhat-frequent calibration and they are not able to detect situations where the pre-set torque has been achieved in a defective way (for instance, a floating screw); for applications with higher complexity and precision needs, more advanced technologies are available. Read on to find out what they are…
FAB screwdriver, clutch detail
Current-controlled electric screwdrivers
As mentioned before, there’s many cases when the operator requires a more sophisticated tool for their fastening operations.
For instance, if an operator needs to tighten different fasteners at different torque values and speeds, they will need a programmable electric screwdriver. They may also need to ensure a lower torque variance between fastening operations or be able to measure & display the torque being applied while in use.
A smarter electric precision screwdriver is therefore needed and that’s where current-controlled electric screwdrivers like Kolver’s PLUTO, MITO and NATO come in.
These tools make it possible, via a control unit, to control and measure both the torque as well as the rotation angle of the screw, guaranteeing remarkable precision in the tightening process.
Featuring a wide torque range of up to 620 lbf-in, these current-control screwdrivers can simultaneously handle up to 8 different types of joint for a single assembly task and their unique electronic torque control system ensures high repeatability between operations as well as full traceability of each operation for quality control.
Generally speaking, current control tools require less-frequent calibration than clutch tools, all while offering a significant improvement in precision of final torque.
Current control tools are considered an excellent balance between cost and precision and a great match for assembly where higher torque accuracy is required for error-proof manufacturing and where communication & traceability is important.
PLUTO screwdriver and its control unit
Torque-controlled electric screwdrivers
However, there is an even smarter class of torque electric screwdrivers, that utilize a built-in transducer for maximum precision in applying the desired torque.
The transducer controls and displays the torque and angle output in real-time, and can also visualize them as graphs, giving the user powerful ways to evaluate different joints and materials.
This class of electric screwdrivers typically comes with highly sophisticated controllers that support more options and more complex tightening strategies than current-control tools, and are the ideal solution for Industry 4.0 production lines.
They also allow for a number of different programmable joints that’s often more than an order of magnitude greater than typical current control screwdrivers, all while offering more user-friendly interfaces.
For instance, Kolver’s K-DUCER line of electric screwdrivers includes a state-of-the-art touch-screen controller that’s as easy to use as an iPhone app but gives the operator up to 200 different programs as well as very advanced torque strategies.
For example, a self-threading application might require an initial torque to overcome the self-threading action that is higher than the target-closing torque. In this case, the user would program the K-DUCER screwdriver to have a max-power torque phase to overcome the self-threading resistance and then proceed with the next programmed steps to achieve the desired target torque, tracking and reporting the entire operation within the controller and over the network.
Another use case that would warrant a transducer screwdriver is running or prevailing torque, common in the aerospace and automotive industries, where a variable amount of driving torque is required to overcome the friction of a fastener. This friction contributes to the total torque applied to the fastener, yet does not directly affect the clamping force to it. In other words, the residual torque will end up being lower than the applied torque by the amount of torque needed to overcome that friction, unless the right amount of compensation is applied.
A transducerized electric screwdriver can dynamically detect and overcome this driving torque and prevent it from affecting the desired torque value by compensating for the encountered friction.
Transducerized smart tools can help with many other complex operations and therefore the higher cost is usually warranted.
K-DUCER screwdriver and its control unit
Conclusions
In summary, clutch electric screwdrivers are common for applications where accuracy and reporting aren’t important. They are cheaper than current control and transducer tools and no programming or set-up is required, other than calibration, which is then carried out with regular cadence.
Current control screwdrivers, while pricier, give operators greater flexibility, higher accuracy and robust quality-control tools. Finally, transducerized screwdrivers justify their generally-higher price tag with best-in-class usability, easier calibration, ultimate precision and full Industry 4.0 compliance.
Selecting the appropriate type of electric screwdriver depends on a variety of factors: budget, precision requirements, complexity of the assembly job, as well as any clean-room and safety regulations.
Clutch-controlled electric screwdrivers
The simplest and most cost-effective tools in the market tend to be clutch-based. Common in the electronic industry, these tools use a clutch to control the amount of torque that’s applied to a fastener.
These tools are very easy to install, operate and maintain. Torque is set near the front of the screwdriver and, during the fastening operation, once the pre-set torque is achieved, the clutch disengages the electric motor.
Clutch screwdrivers like Kolver’s RAF & FAB series (and the brushless KBL series for those seeking maintenance-free screwdrivers) are an excellent choice for high-volume applications in the 0.4 - 44.5 lbf-in range that require ESD compliance, excellent ergonomics & reliability and a quieter and pollutant-free work environment.
Clutch screwdrivers do require somewhat-frequent calibration and they are not able to detect situations where the pre-set torque has been achieved in a defective way (for instance, a floating screw); for applications with higher complexity and precision needs, more advanced technologies are available. Read on to find out what they are…
FAB screwdriver, clutch detail
Current-controlled electric screwdrivers
As mentioned before, there’s many cases when the operator requires a more sophisticated tool for their fastening operations.
For instance, if an operator needs to tighten different fasteners at different torque values and speeds, they will need a programmable electric screwdriver. They may also need to ensure a lower torque variance between fastening operations or be able to measure & display the torque being applied while in use.
A smarter electric precision screwdriver is therefore needed and that’s where current-controlled electric screwdrivers like Kolver’s PLUTO, MITO and NATO come in.
These tools make it possible, via a control unit, to control and measure both the torque as well as the rotation angle of the screw, guaranteeing remarkable precision in the tightening process.
Featuring a wide torque range of up to 620 lbf-in, these current-control screwdrivers can simultaneously handle up to 8 different types of joint for a single assembly task and their unique electronic torque control system ensures high repeatability between operations as well as full traceability of each operation for quality control.
Generally speaking, current control tools require less-frequent calibration than clutch tools, all while offering a significant improvement in precision of final torque.
Current control tools are considered an excellent balance between cost and precision and a great match for assembly where higher torque accuracy is required for error-proof manufacturing and where communication & traceability is important.
PLUTO screwdriver and its control unit
Torque-controlled electric screwdrivers
However, there is an even smarter class of torque electric screwdrivers, that utilize a built-in transducer for maximum precision in applying the desired torque.
The transducer controls and displays the torque and angle output in real-time, and can also visualize them as graphs, giving the user powerful ways to evaluate different joints and materials.
This class of electric screwdrivers typically comes with highly sophisticated controllers that support more options and more complex tightening strategies than current-control tools, and are the ideal solution for Industry 4.0 production lines.
They also allow for a number of different programmable joints that’s often more than an order of magnitude greater than typical current control screwdrivers, all while offering more user-friendly interfaces.
For instance, Kolver’s K-DUCER line of electric screwdrivers includes a state-of-the-art touch-screen controller that’s as easy to use as an iPhone app but gives the operator up to 200 different programs as well as very advanced torque strategies.
For example, a self-threading application might require an initial torque to overcome the self-threading action that is higher than the target-closing torque. In this case, the user would program the K-DUCER screwdriver to have a max-power torque phase to overcome the self-threading resistance and then proceed with the next programmed steps to achieve the desired target torque, tracking and reporting the entire operation within the controller and over the network.
Another use case that would warrant a transducer screwdriver is running or prevailing torque, common in the aerospace and automotive industries, where a variable amount of driving torque is required to overcome the friction of a fastener. This friction contributes to the total torque applied to the fastener, yet does not directly affect the clamping force to it. In other words, the residual torque will end up being lower than the applied torque by the amount of torque needed to overcome that friction, unless the right amount of compensation is applied.
A transducerized electric screwdriver can dynamically detect and overcome this driving torque and prevent it from affecting the desired torque value by compensating for the encountered friction.
Transducerized smart tools can help with many other complex operations and therefore the higher cost is usually warranted.
K-DUCER screwdriver and its control unit
Conclusions
In summary, clutch electric screwdrivers are common for applications where accuracy and reporting aren’t important. They are cheaper than current control and transducer tools and no programming or set-up is required, other than calibration, which is then carried out with regular cadence.
Current control screwdrivers, while pricier, give operators greater flexibility, higher accuracy and robust quality-control tools. Finally, transducerized screwdrivers justify their generally-higher price tag with best-in-class usability, easier calibration, ultimate precision and full Industry 4.0 compliance.