Motion control for metal forming, fabrication and welding

In short:Metal forming and fabrication machines need high force or torque with controlled motion: roller-screw actuators and servo presses for pressing and punching, servo motors on feeds, benders and roll formers, high-torque gearboxes on weld positioners, and slip rings that carry weld current and signals across rotating axes. Size from the peak load and how long it lasts, then check heat, screw life and safety category.

Typical requirements

Machinery we specify motion for

• Servo presses and punch presses
• Press brakes and sheet metal folders
• Laser cutting machines and tube lasers
• Roll forming lines and flying cut-off
• Tube bending and end forming
• Resistance spot and projection welding
• Weld positioners, turning rolls and wire feeders
• Casting, foundry and mould handling
• Metal additive manufacturing

What metal forming and fabrication demand from motion

Forming and fabrication machines combine very high forces with short, repeated strokes. A punch press, press brake or clinching head may see several kilonewtons to hundreds of kilonewtons for a fraction of a second, thousands of times a shift, in a shop full of scale, spatter, oil mist and vibration. Laser cutters add high acceleration and accuracy; welding cells add weld current, noise and heat.

Three shifts are under way across the sector:

• Hydraulics to electric. Roller-screw actuators and servo presses replace hydraulic cylinders where force and position must be controlled, oil is unwelcome and energy matters. Tolomatic’s metals and fabrication list covers cutting, punching, stamping, pressing, forming, tube bending, clamping, welding and riveting, and a casting manufacturer that replaced high-maintenance hydraulic actuators with an electric roller-screw actuator.
• Flywheels to servo drives. Servo presses make slide motion programmable.
• Pneumatics to servo on weld guns, clamps and part ejection, for repeatable force.

Where motion components sit in a fabrication shop

Servo presses and electric press actuators

A servo press replaces the flywheel and clutch with servo drive. Schuler builds monoblock servo presses at 2,500, 4,000 and 6,300 kN, driven directly by gearless torque motors, with programmable strokes and rest times so welding or laser operations can run in the die. Its pendulum mode, which runs a shortened stroke back and forth, raises stroke rate and is described as highly energy-efficient.

Below that scale, electric rod actuators handle punching, piercing, clinching and assembly pressing. Published roller-screw ranges run from the RSA-HT (about 58 kN) to the RSX (about 294 kN in the catalogue range). For conversions, read our hydraulic to electric actuator guide and ball screw vs roller screw.

Press safety in Europe is covered by the EN ISO 16092 series. Pilz summarises it: Part 1 covers all presses, Part 2 mechanical presses (replacing EN 692), Part 3 hydraulic presses (replacing EN 693, harmonised since March 2019) and Part 4 pneumatic presses, with safety functions now assessed to EN ISO 13849-1. Presses are Annex IV machinery, with a stricter conformity route.

Press brakes: hydraulic, hybrid or electric

The Fabricator describes the three drive types. Ball screw electric brakes use a servo motor and belt to a screw; they draw very little power at idle and some reach about 1 µm positioning, but historically they have been lower tonnage machines. Pulley-drive electrics multiply motor force through a pulley system. Hybrids drive a fixed-displacement pump with a servo motor, using about one-third to one-half the oil of a conventional hydraulic brake. During the bend all types draw similar power; the savings come from idle time. Backgauge axes on all of them are servo axes needing accurate, rigid feedback.

How to size a weld positioner drive: a worked example

Take a two-axis positioner carrying a 500 kg fixture and workpiece. The combined centre of gravity sits 150 mm off the rotation axis and 300 mm above the tilt axis. Rotation runs up to 3 rpm.

1. Rotation torque. 500 × 9.81 × 0.15 ≈ 736 Nm eccentric torque. Add bearing friction and a small acceleration allowance: call it 800 Nm.
2. Tilt torque. 500 × 9.81 × 0.30 ≈ 1,470 Nm, worst case with the table at 90°. Call it 1,600 Nm.
3. Ratio. A 3,000 rpm servo motor to 3 rpm needs about 1,000:1, for example a 100:1 planetary gearhead driving a 10:1 pinion and slewing ring.
4. Motor torque. Rotation: 800 ÷ (1,000 × 0.9) ≈ 0.9 Nm. Tilt with a similar ratio: about 1.8 Nm. Small motors suffice; the gear train and bearing carry the real load.
5. Brake and back-driving. With power off, the eccentric load tries to turn the table. The motor brake must hold the reflected torque with margin, and the gearbox and slewing ring must take the full static torque and tilting moment.
6. Weld current. If the positioner rotates continuously, the earth return passes through a high-current brush ring or rotary earth sized to the weld current and duty cycle; sensor and clamp signals go on separate, shielded rings. See slip rings for welding positioners and high-current slip rings.

Treat these numbers as illustrative. Use the gearbox maker’s efficiency, output bearing and emergency-stop torque data.

Laser cutting, roll forming and tube bending

Laser cutters need acceleration and contour accuracy. SCHLEIFRING notes that slip rings on cutting centres carry power and data to the motor and help keep the laser head aligned. Linear motors on the gantry remove screws and backlash; see the linear actuators hub. Roll forming lines use servo stand drives and a flying shear or punch that matches line speed during the cut, so feed length accuracy depends on encoder resolution and on the controller’s cam profile. Tube benders coordinate bend arm, carriage, rotation and clamp axes; electric clamp and pressure-die actuators replace hydraulics on many modern benders. See servo vs stepper for smaller auxiliary axes.

Foundry, casting and steel mill duty

Foundries and steel plants are where electric actuation is hardest and where hydraulic leaks cost most. Radiant heat, molten metal splash, abrasive dust and scale attack seals, wipers, cables and encoders. Before choosing a standard industrial actuator, check its rated ambient temperature range against the real temperature at the mounting point, not the shop average, and add heat shields, cooling air or a remote motor mounting where needed. Specify IP65 or IP67 sealing, a rod boot or scraper, and connectors and cables rated for the heat. Keep feedback devices and drives as far from the heat source as possible, and plan for failure modes: a fail-safe brake or spring return may be needed where a stalled actuator would leave a ladle or mould in an unsafe position. For mould handling and ejection on casting machines, the same sizing approach as a press applies: force, stroke, speed, and how long the force is held.

Things that catch engineers out

1. Sizing on peak force only. Holding force heats the motor; check RMS torque and screw life.
2. Side load on rod actuators. Guide the tooling; actuator rods are not designed for bending loads.
3. Weld noise on encoder and fieldbus cables. Separate routing, shielding and earthing matter.
4. Eccentric loads back-driving positioners. Brakes and gears must hold the full static torque.
5. Scale, slag and dust. Specify wipers, bellows, sealed scales and suitable IP ratings.
6. Regenerative energy from presses and shears. Plan resistors or a shared DC bus.

What to send an engineer

• Machine type and the force or torque profile through each cycle.
• Stroke, speeds, cycle rate, shifts and expected life.
• Moving mass, orientation, centre of gravity (positioners) and space envelope.
• Environment: heat, spatter, scale, oil, vibration.
• Controller, fieldbus, encoder interface and safety functions with target PL.
• For conversions: existing cylinder bore, rod, pressure and stroke.

Our specialist engineering and supply partners can propose matched actuators, motors, gearboxes and drives. Start in the spec builder.

Standards to have in view

• EN ISO 16092-1 (presses: general safety requirements)
• EN ISO 16092-2 (mechanical presses; replaces EN 692)
• EN ISO 16092-3 (hydraulic presses; replaces EN 693)
• EN 12622 (hydraulic press brakes: safety)
• EN ISO 11553-1 (laser processing machines: safety)
• IEC 62135-1 (resistance welding equipment: safety)
• ISO 13849-1 (safety-related parts of control systems)
• Regulation (EU) 2023/1230 (machinery; applies from 20 January 2027)

Which standards apply depends on the end product and its market. Your engineer will confirm what the component itself needs to meet.