Magnetic chuck for machine tools · Electromagnetic, permanent or electro-permanent, holding force, pole pitch and thin parts, pole extensions, heat and demagnetisation
A magnetic chuck holds ferromagnetic workpieces on a machine tool table by magnetic force instead of clamps. Ask three things first: which operation it serves (grinding, milling, turning or drilling), which technology (electromagnetic, permanent or electro-permanent) fits the accuracy and safety needs, and how thick, how magnetic and how flat the workpieces are.
Magnetic chucks for grinding, milling, turning and drilling machines: electromagnetic, permanent and electro-permanent types with their controllers and pole extensions. Lifting magnets, magnetic bases for indicators, neodymium magnets as parts and vacuum chucks are outside this page.
01
Walmag advises that precision grinding and precision machining need a chuck that does not warm up, because heat can deform the workpiece; it recommends electro-permanent chucks for this, as they do not heat up as electromagnets do. Heavy-duty grinding needs high force and robust construction; round chucks give five-side access for lathe turning without re-clamping; and for drilling, extensions raise the part so the drill does not reach the chuck. [1]
Tecnomagnete describes its MILLTec permanent-electro chuck for machining centres and milling machines as a honeycomb mono-block with a 100% steel surface, clamping the workpiece in seconds at up to 16 kg/cm², with no effect from power outages because it is a permanent-electro system, and leaving five faces free for machining in one set-up; its /SC version with a recess holds thin pieces of 10 mm. [2]
For grinding, Tecnomagnete's GrindTec permanent-electro chucks are offered as an alternative to electromagnetic grinding tables that do not overheat, with four polar geometries, machine thickness from 2 mm, parts from 5 mm thick, a monoblock frame with pole pitches chosen by machine, no current flowing during machining and a patented demagnetisation system. [3]
Editorial calculation: 16 kg/cm² ≈ 157 N/cm² (16 × 9.81). [2]
Give the supplier the machine type and table size, operation, workpiece material, size, minimum thickness and contact area, required accuracy, chuck technology and pole pitch, controller voltage and demagnetisation, coolant use, pole extensions needed and mounting interface.
02
Walmag states that a workpiece must be ferromagnetic, that the field is strongest for low-carbon steel, and that high-carbon and alloy steel need more clamping force because they contain non-magnetic elements; dirt, dust, paint or polish layers and perforations all reduce holding force. [1]
Walmag says standard magnetic chucks securely clamp workpieces down to 12 mm thick; thinner parts need a chuck with denser poles or a top pole plate milled to the part shape, and a stronger chuck alone does not help because the flux passes through a thin part and closes behind it. It offers custom chucks for parts of 4 mm cross-section, and firm and flexible pole extensions to set a reference level and follow irregular shapes. [1]
Tecnomagnete states that its double-inclined pole extensions transmit flux with a 20% increase in magnetic yield compared with single-inclined extensions. [2]
03
Kanetec's product page for its EP-Q permanent electromagnetic chuck for milling machines and machining centres gives a size table that shows how working area, pole count and mass scale together. Model EP-QN5-3060A measures 300 × 610 mm with 24 poles and a mass of 90 kg; EP-QN5-4080A is 420 × 800 mm with 40 poles and 160 kg; EP-QN5-50100A is 500 × 960 mm with 60 poles and 230 kg; EP-QN7-4080A is 390 × 800 mm with 24 poles and 150 kg. The chuck is 70 mm high, the maximum one-piece size is 1,300 × 1,500 mm with larger chucks made by connecting units, and non-standard sizes are offered. Kanetec states that electricity is needed only when mounting and dismounting workpieces, that workpieces stay held during a power failure, that the chuck can be used wet, that tapped holes on the face take blocks, and that hardened or special steels may be hard to dismount because of strong residual magnetism. [4]
Editorial calculation: EP-QN5-3060A carries 24 poles on 0.183 m² and weighs about 490 kg per m² of face (90 ÷ 0.183); EP-QN5-4080A carries 40 poles on 0.336 m² at about 476 kg/m². The EP-QN7-4080A has a similar face but 24 poles, so pole size differs between the two series; match pole size to the thinnest part, since Walmag notes that thin parts need denser poles. [4] [1]
Add the chuck's mass to the fixture load the machine table is rated for, check that its 70 mm height fits the machine's Z travel with the tallest part, and ask the supplier for a demagnetisation cycle suited to hardened parts. [4] [3]
04
The suppliers linked to this page list magnetic chucks; their cards link to the pages reviewed.
Ask any supplier for the chuck technology, holding force with the test piece described, pole pitch and pole layout, working surface size, flatness and parallelism, controller and demagnetisation cycle, supply voltage, sealing against coolant, weight, and extensions or top plates available.
05
This is a functional reference built from the sources cited; it is not one maker's specification.
| Part | Role | Fix in the order |
|---|---|---|
| Top plate and poles | Carry flux into the workpiece. [2] [1] | Pole pitch; steel surface. |
| Magnets and coils | Create or switch the field. [3] [1] | Electro, permanent or EP. |
| Frame | Holds poles; shields circuit. [2] [3] | Monoblock; thickness. |
| Controller | Magnetises and demagnetises. [3] | Voltage; demag cycle. |
| Pole extensions | Raise and conform to parts. [1] [2] | Fixed or flexible. |
06
A magnetic chuck quotation needs values for your machine and parts. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Magnetic Force (N/cm²) | e.g. up to 16 kg/cm² ≈ 157 N/cm² (MILLTec). [2] | Force; test conditions. |
| Pole Pitch (mm) | Chosen by machine and part thickness; denser poles for thin parts. [3] [1] | Pitch. |
| Flatness (mm) | Not stated in the reviewed sources. | Tolerance. |
| Parallelism (mm) | Not stated in the reviewed sources. | Tolerance. |
| Maximum Workpiece Temperature (°C) | Not stated; electro-permanent chucks avoid heating. [1] | Limit. |
| Operating Voltage (V DC) | Not stated in the reviewed sources. | Controller supply. |
| Power Consumption (W) | No current during machining (permanent-electro). [3] [2] | Magnetising pulse. |
| Ingress Protection | Sealed against coolant and residues. [3] | Rating. |
| Body Material | Steel monoblock surface. [2] | Material. |
| Weight (kg) | Not stated in the reviewed sources. | Weight. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Machine: [type; table size] Operation: [grinding; milling; turning; drilling] Technology: [electromagnetic; permanent; electro-permanent] Workpiece: [material; size; minimum thickness] Accuracy: [flatness; parallelism] Accessories: [pole extensions; top plate; controller]
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Walmag recommends electro-permanent chucks because they do not heat up as electromagnets do. [1]
Walmag says standard chucks hold parts down to 12 mm; thinner parts need denser poles or a shaped top plate. [1]
Tecnomagnete states power outages have no effect on its permanent-electro chuck's holding force. [2]
Kanetec's EP-Q series runs from 90 kg for a 300 × 610 mm, 24-pole chuck to 230 kg for a 500 × 960 mm, 60-pole chuck, all 70 mm high; add this to the machine table load. [4]
Sources checked 2026-10-11. Walmag, Tecnomagnete (MAG-AUTOBLOK) and Kanetec make magnetic chucks and publish selection guidance and specifications.
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