TECNA 2933 Light Servo-Driven Robotic Spot Welding Gun

The TECNA 2933 Light robotic spot welding gun is designed for automated resistance welding applications requiring an X-type articulated welding mechanism and servo-controlled electrode movement. The gun uses TECNA's universal motorless actuator, designed to be driven by a compatible servomotor from the robot manufacturer. This arrangement allows the electrode closing and opening movements to be coordinated with the robotic welding sequence, making the gun suitable for integration into industrial production cells.

One of the main considerations when selecting the TECNA 2933 is the relationship between electrode force and welding arm length. With the specified 4.9 Nm actuator arrangement, the gun develops 600 daN using 300 mm arms, 470 daN with 450 mm arms and 380 daN with 600 mm arms. Longer arms provide access to weld locations positioned further inside a sheet metal assembly, but the mechanical leverage reduces the force available at the electrodes. The correct configuration therefore depends on both the required reach and the clamping force established for the welding process.

The gun is available with 52 kVA or 82 kVA Light MFDC welding transformers, with nominal power specified at a 50% duty cycle. The 52 kVA transformer has a no-load secondary voltage of 6.1 V, thermal current of 5.5 kA and short-circuit current of 20 kA. The 82 kVA version provides 9.1 V, 6 kA and 25 kA respectively. Both transformer configurations are available for 500 V / 1000 Hz or alternatively 600 V / 1000 Hz supply. Transformer selection must reflect the required welding current, the properties of the materials and the electrical characteristics of the secondary welding circuit.

The MFDC resistance spot welding process uses electrical current and electrode pressure to generate heat at the interfaces of the metal sheets. The resulting weld nugget is affected by welding current, welding time, electrode force, material thickness and surface condition. Although the servo-driven mechanism allows the electrode movement to be managed through the robot control system, the mechanical drive and the welding controller perform different functions. Both must be configured correctly to obtain suitable welding conditions.

TECNA designed the 2933 actuator for use with compatible servomotors from industrial robot manufacturers. The manufacturer's documentation lists motor configurations associated with Yaskawa, Fanuc, ABB, Kawasaki, Nachi, KUKA, Hyundai and Estun. A servomotor speed of 3000 rpm is specified in the technical catalogue. The available motor torque, mechanical coupling and robot control interface must be evaluated before selecting a particular combination. Compatibility with a robot manufacturer's motor range does not mean that every motor model can be installed without further technical assessment.

Servo actuation is particularly useful when the electrode movement needs to be adapted to the component geometry or welding sequence. Approach speed and closing movement can be programmed to reduce unnecessary mechanical impacts when the electrodes contact the workpiece. This can be relevant when welding thin sheets or assemblies in which excessive mechanical stress may affect component positioning. The actual result depends on the actuator configuration, robot programming and correct application of the required welding force.

Robot payload and gun mounting geometry are equally important during integration. With 300 mm arms, arm fittings, transformer and a reference servomotor weighing 6 kg, the TECNA 2933 has a documented mass of 72.9 kg with the 52 kVA transformer or 74.9 kg with the 82 kVA transformer. These figures must be considered together with the centre of gravity, inertia and acceleration requirements of the robotic cycle. Alternative motors, longer arms or different mounting arrangements may change the loads experienced by the robot wrist.

TECNA provides several robot connection arrangements, including top, bottom, rear and 45-degree mounting configurations. Right-hand and left-hand mirrored versions and symmetrical layouts are also illustrated in the manufacturer's catalogue. These mounting options allow the gun to be positioned according to robot movement, fixture clearance and access to the required welding points. The installation must also consider cooling connections, cables and potential interference with nearby equipment.

The available welding arm and electrode holder configurations include copper arms and arrangements incorporating aluminium components. Arm geometry affects access to the joint, current conduction and structural behaviour under load. Additional options include an actuator load cell for monitoring electrode force during welding and a servomotor cooling system intended for demanding operating conditions. The suitability and availability of these options must be checked against the selected gun configuration.

The TECNA 2933 specifies 12 l/min cooling water flow for the gun and 4 l/min for the transformer. Adequate cooling is necessary to manage heat generated in the electrodes and current-carrying components during repeated welding cycles. Insufficient water circulation may accelerate electrode wear and cause variations in contact conditions. Cooling requirements must therefore be considered when designing or adapting the services of the robotic welding cell.

The TECNA 2933 robotic welding gun can be used in automated sheet metal assembly, automotive manufacturing and industrial production of resistance spot welded components. A.T.S. supplies the equipment and provides technical advice on transformer selection, required arm length, available welding force, motor compatibility and robot mounting. Evaluating these factors before installation helps manufacturers select a configuration suited to the actual welding application and the operating limits of the robotic system.