No matter what type of welding tongs you use – X-welding tongs for spots that are hard to access, or C-welding tongs for simpler constructions – the electric cylinders by SEW‑EURODRIVE are perfectly suitable for both applications and will provide you with a repeat accurate welding power: Our electric cylinders can provide a peak drive force of up to 10 kN in C-welding tongs, and up to 24 kN in X-welding tongs.
Spot welding – A challenging task
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Wartungsfreie Antriebe für Schweißzangen. Keine Zukunftsmusik sondern Realität. Dank der patentieren Ölbadschmierung des Elektrozylinders von SEW-EURODRIVE!
There's no accounting for taste when it comes to the looks of a car body – but when it comes to the importance it's greatest task, protecting the passengers from harm as good as possible, everyone will agree upon it. In order to ensure the safety of the passengers, the car body must be torsionally rigid and the other components must be firmly attached to it. In case of alternative drive and mobility concepts, the need to combine a mixture of different materials, such as steel, aluminum, plastic, and composite materials must also be taken into consideration.+
This secure connection is created by thousands of welding spots on the car body, the doors, the hood, etc. Each component contributes to the rigidity of the vehicle and thus to protecting the passengers. In car body manufacturing, the welding spot connections are performed fully automatic with consistent precision and quality.
For exactly this purpose, electric cylinders are used to evenly generate the force of the welding tongs. In order for a welding spot to meet all quality requirements, the welding electrodes must be constantly pressed together and held with the correct amount of force during the welding procedure.
Repeat accuracy, process reliability and durability are just as important quality criteria for the used welding tongs drive, as accurately positioning the welding spots so that the surrounding surfaces aren't damaged. This includes that welding spatter does not occur when a welding tong application functions optimally.
The technical solution

The mechanical design of our electric cylinders is variable, so that it exactly fits to the used welding tong construction, whether you use X-tongs or C-tongs.
The design of the electric cylinder is selected depending on:
- Available installation space
- Required stroke
- Required welding power
- Required speed
- Used control system

More properties of the electric cylinders:
- Maintenance-free for the entire service life due to the patented bath lubrication
- No regreasing required throughout the entire service life
- Very high efficiency
- Easy to install
- Excellent power density / enhanced heat distribution via bath lubrication
- Twice the service life as compared to the market standard
- Low costs throughout the service life and higher OEE as compressed air preparation of the electric cylinder is not needed
- Easily integrated into control systems using flexible encoder systems and connector options
- Exact positioning thanks to ball screws using servo drive technology with high-precision encoders
- Perfect force and repeat accuracy throughout the entire service life, with no need of additional sensors
- Very low noise as compared to pneumatically operated welding tongs
System integration via plug-and-play
Two variants to integrate electric cylinders are available:
- As 7th axis in the robot controller: With this variant, the motion of the robot (6 axes) and the opening/closing motion of the welding tongs (7th axis) are defined by the robot controller, e.g. KUKA, ABB or Fanuc. An welding controller is additionally required to regulate the welding current.
- Using the Bosch Rexroth welding control PRC7300 or PRC7400: A robot controller controls the 6 axes, but out electric cylinder and the welding current are controlled and adjusted to each other by the PRC7300 and PRC7400.
Comparison of the 3 systems
Convetional | Market standard | Future-proof | |
---|---|---|---|
Design / selection criteria | Pneumatic cylinders | Planetary screw drive with grease lubrication | Ball screw with bath lubrication |
Service life | Depending on maintenance | Depending on regreasing | For the entire service life |
Speed | Up to 3 m/s | Up to 1.5 m/s | Up to 0.75 m/s |
Weight and required space | Low | Moderate | Moderate |
Noise level | High | Moderate | Low |
Efficiency | 7 – 10% | 60 – 80% | 86 - 92% |
Force precision | Low | Force gauge required | +/- 150 N |
Positioning accuracy | Moderate | High | High |
Maintenance | Regular tightness maintenance every 1.2 million cycles | Regular relubrication every 2 million cycles |
Maintenance-free for the entire service life |
Controllability in the process (speed, power, starting behavior) | No speed control | Average control, slip-stick effect at the beginning of a stroke | Easy and precise controllability |
Environmental impact | Very low efficiency 1 | More grease required, low efficiency | Oil only needs to be disposed of after the service life ends, very high efficiency |
Characteristic stability in case of temperature changes etc. throughout the service | Risk of leaks in the compressed air system, speed depending on the compressed air | Very high stability, independent of the temperature | Very high stability, independent of the temperature |
Additionally required tools | Compressed air supply, pressure reduction, sensors, pneumatics controller | Cables for motor feedback and power supply, servo controller, local relubrication tools | Cables for motor feedback and power supply, servo inverter, |
Welding spot quality | Repeat accuracy, positioning and force control depending on air leaks, the construction cannot be controlled very accurately |
High repeat accuracy, positioning and force control |
High repeat accuracy, positioning and force control |
Reliability of the overall system | Ca. 11 million cycles when the cylinders are regularly checked and resealed |
Ca. 11 million cycles when the cylinders are regularly checked and resealed | 20 million cycles |
|
Technical Data
Electric cylinder | Stroke | Maximum feed speed |
Peak feed force | Continuous feed force |
Weight |
---|---|---|---|---|---|
mm | m/s | kN | kN | kg (stroke lenght 160 mm) |
|
Size 50 | 70 – 600 | 0.75 | 2.65 – 8 | 0.6 – 3.2 | 5.8 – 13.6 |
Size 63 | 60 – 600 | 0.45 | 10 | 2.4 – 5.2 | 8.8 – 18.6 |
Size 71 | 100 – 1200 | 0.45 | 18 – 24 | 6.2 – 12 | 21.6 – 48.7 |
Dimensions - axially parallel
Electric cylinder | A | B | H | Y | LB |
---|---|---|---|---|---|
Size 50 Type S / M / L |
73 | 217 | 70 / 100 / 150 / 200 / 300 / 400 / 600 | 221.5 / 251.5 / 301.5 / 351.5 / 451.5 / 581.5 / 781.5 | Type S: 174.5 Type M: 223.5 Type L: 262.5 |
Size 63 Type S / M / L |
88 | 245.5 | 60 / 100 / 160 / 180 / 200 / 400 / 600 | 235.5 / 275.5 / 335.5 / 355.5 / 375.5 / 607.5 / 807.5 |
Type S: 252.8 Type M: 302.8 Type L: 352.8 |
Size 71 Type S / M / L |
115 | 291 | 100 / 160 / 200 / 400 / 600 / 800 / 1000 / 1200 |
326 / 386 / 426 / 686 / 886 / 1146 / 1346 / 1546 |
Type S: 229 Type M: 254 Type L: 304 |
|
Dimensons - axially serial
Electric cylinder | A | B | H | Y | LB |
---|---|---|---|---|---|
Size 50 Type S / M / L |
73 | 120.7 | 70 / 100 / 150 / 200 / 300 / 400 / 600 |
221.5 / 251.5 / 301.5 / 351.5 / 451.5 / 581.5 / 781.5 | Type S: 156.4 Type M: 195.4 Type L: 234.4 |
Size 63 Type S / M / L |
88 | 245,5 | 60 / 100 / 160 / 180 / 200 / 400 / 600 | 235.5 / 275.5 / 335.5 / 355.5 / 375.5 / 607.5 / 807.5 | Type S: 163.7 Type M: 214.2 |
Size 71 Type S / M / L |
115 | 295 | 100 / 160 / 200 / 400 / 600 / 800 / 1000 / 1200 |
326 / 386 / 426 / 686 / 886 / 1146 / 1346 / 1546 | Type S: 211 Type M: 236 Type L: 286 |
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