Home / Electric, Magnetic & Vacuum Clamping

Electric, Magnetic & Vacuum Clamping

Power-driven devices that hold the workpiece without conventional mechanical clamps. Ideal for thin plates, non-magnetic or easily damaged parts, and for fully automatic cycles.

1Electric (Motor-Driven) Devices

A small electric motor drives the clamp through a screw or cam mechanism. Used where shop air or hydraulics are not available, or where precise, stepless clamp travel is required.

Self-locking screw drive holds the clamp without power.
Controllable force and stroke; easy to automate with limit switches.
Slower than pneumatic or hydraulic for large strokes.

Always fit a torque or force limiter so the motor cannot over-clamp a thin or fragile part.

2Electromagnetic Chuck

A DC coil magnetizes the whole top plate; the workpiece is held by magnetic attraction. Force is constant and controllable by current.

Holds ferromagnetic parts across the full plate area.
Fast, even holding — ideal for grinding and milling thin plates.
Fails safe only with residual magnetism control; add a mechanical backup for vertical or heavy parts.

Flux exits the poles, closes through the workpiece and returns through the coil core

Permanent Magnet Chuck

Uses permanent magnets switched on/off by rotating an internal magnetic circuit. No power needed to hold; ideal for work on light-duty machines.

Zero running cost and no heat generation.
Lower holding force per area than an electromagnetic chuck.
Not suited to interrupted cuts with heavy vibration.

Rotating a drive inside the chuck flips the strips between holding and neutral

3Vacuum Chuck

The workpiece seals against a faceplate; a vacuum pump removes air beneath it, and atmospheric pressure presses the part down. Holds ANY material — steel, aluminium, glass, plastic, ceramic.

F = p · A

F — holding force (N)
p — vacuum differential (N/mm²; 0.06–0.09 MPa typical)
A — effective sealed area (mm²)

A 250 × 250 mm plate at 0.08 MPa holds ≈ 5000 N. A clean seal and a flat, burr-free part are essential.

Atmospheric pressure presses the part onto the sealed pad while the pump removes the air beneath it

4Vacuum Workholding Notes

Grooved or drilled top plates adapt the vacuum zone to the part outline.
Keep the surface clean and flat; chips break the seal and cut the holding force.
Use a vacuum reservoir and check valve to hold pressure on pump failure.
For thin sheets, support the full area to prevent deflection under suction.

The groove network carries vacuum to the rim of the part so the seal covers the outline

5Self-Clamping Devices

A self-clamping device uses the cutting force itself to increase clamping action — the harder the cut, the tighter the hold. Common on milling and planing fixtures.

Wedge or cam surfaces convert cutting force into extra clamp force.
No external power source required.
Direction-sensitive: the cutting force must act to tighten, not release, the clamp.

Check the cutting direction carefully — a reversed feed would release the workpiece.

Selection Guide

Device	Material held	Best for	Limitation
Electromagnetic	Ferromagnetic only	Grinding/milling steel plates, heavy parts	Power needed; not for non-magnetic
Permanent magnet	Ferromagnetic only	Light work, no power available	Lower force, sensitive to vibration
Vacuum	Any sealed material	Thin sheets, aluminium, glass, plastic	Clean flat seal essential
Self-clamping	Rigid parts	Milling/planing, no power source	Feed direction must be correct

For most production magnetic/vacuum work, combine the primary device with positive mechanical stops in the feed direction so a power failure cannot shift the part.