01
Where magnets earn their place in a machine
The recurring wins, and the constraint attached to each:
| machine function | why magnetic | the constraint |
|---|---|---|
| Part gripping & EOAT | No air, no power to hold, flat-surface pickup, fast cycling | Ferrous parts only; release needs a mechanism; force falls hard with gap — section 02 |
| Fixtures & workholding | Clampless, fast changeover, clean access to the part | Shear loading and machining forces need margin; chips accumulate on the field |
| Sensing targets | Non-contact, sealed, survives washdown and grime | The target is a specified component, not “any magnet” — section 03 |
| Couplings & sealed drives | Torque through a wall — zero-leak pumps, sterile barriers | Slip = heat = demagnetization risk; overload behavior must be designed |
| Conveyance & sheet handling | Sheet fanning, can/lid transfer, holding on inclines and inversions | Impact and abrasion duty; coating and mounting take the abuse |
| Latching, detents & doors | Silent, wear-free positioning and closure | Consistent force needs consistent gap — tolerance the interface |
02
EOAT, grippers & holding
- Derate catalog pull force ruthlessly. Ratings assume thick, flat, clean, mild steel at zero gap. Real automation picks painted, oily, thin-gauge, or curved parts through an air gap — each factor cuts force, and they multiply. The physics and derating logic are in the pull force guide; validate on the actual part, then apply a safety factor sized to what happens if the part drops.
- Shear is not pull. Sliding resistance is a fraction of breakaway force — a gripper rated comfortably for lift can lose parts to lateral acceleration on a fast move. Design pick orientation and motion profiles together.
- Use pot (cup) magnets, not bare magnets, for holding duty. The steel cup multiplies force on flat contact, armors the brittle magnet against impact, and provides the threaded mounting a bare magnet can't — a factory-made countersunk or pot format, never a field-drilled magnet.
- Design the release. Permanent-magnet gripping needs a mechanical stripper, a pneumatic ejector, or a lever-off geometry; electropermanent modules trade cost for switchable holding with power-off safety. Decide before the EOAT envelope is frozen.
- Cycle-life lives in the mounting: millions of pick cycles fatigue-load adhesive joints and shock-load the magnet. Mechanical capture plus adhesive — the machine-duty reading of the bonding & mounting guide — is the difference between a wear item and a warranty claim.
03
Sensing targets & position feedback
Every cylinder switch, door interlock, speed pickup, and rotary encoder with a magnet in it has the same rule: the magnet is half the sensor, and it's the half integrators improvise. The full treatment is the sensor magnet guide; the integration shortlist:
- Spec the target as a component: size, grade, magnetization direction, and the field the sensor needs at the real working gap — not “a magnet from the drawer.” Substituting a stronger magnet moves switch points just as surely as a weaker one.
- Direction is the usual bug: axial vs. diametric targets produce different field shapes at the sensor; a correct-size wrong-direction magnet gives intermittent, position-dependent behavior that looks like a wiring fault. Patterns in the directions guide.
- Budget the thermal drift: NdFeB fields drop ~0.12%/°C — a threshold sensor set at commissioning in winter reads differently beside a hot spindle in July. Set thresholds with temperature margin, or use direction-based sensing that cancels drift.
- Through-shaft and speed applications lean on multipole and true radial rings — pole count sets resolution, and one-piece true radial construction avoids the segment-joint signal dips; drawing language in the directions guide, hardware in the True Radial line and sensor magnet range.
- Document the target in the machine manual with the same part discipline as the sensor — the replacement scenario in the customer's plant is a maintenance tech with a drawer of assorted magnets.
04
Couplings & magnetic conveyance
- Design the overload case first. A magnetic coupling that slips under jam converts drive power to heat in the magnets — and hot NdFeB loses coercivity 4–6× faster than it loses strength, so a sustained slip event can permanently derate the coupling, per the temperature guide. Detect slip (speed mismatch) and trip, or size the breakaway torque so slip is the protection and the duration is bounded.
- Temperature class for the real rotor environment: couplings and conveyance magnets near motors, ovens, and hot product run well above ambient — class selection with a load-line check, not the catalog default.
- Conveyance duty is impact duty: cans, lids, and sheet stock hammer the field surfaces. Spec the armor — stainless cladding, pot formats, or replaceable wear faces over the magnets — and a coating chosen for abrasion + washdown from the coatings guide.
- Retention at speed is mechanical, always: rotating magnet carriers get sleeves, pockets, or bands that carry the centrifugal load; adhesive positions, capture retains — the non-negotiable from the bonding guide.
05
Selecting for duty cycle, impact & environment
material by duty
NdFeB for force density in EOAT and compact elements; ferrite for washdown, chemical, and cost-driven conveyance (mind its cold-weather demag quirk); SmCo beside ovens and for thermal stability — the trade study is the material comparison
temperature class by location in the machine
ambient-spec magnets beside spindles, heaters, and un-cooled panels are the classic commissioning-passes / summer-fails pattern — map the thermal reality, then class with margin
coating by environment
Ni-Cu-Ni for dry machine interiors; epoxy or ferrite for coolant, washdown, and chemicals; food-adjacent zones need the sanitation conversation — menu in the coatings guide
stock sizes wherever function allows
machines are low-volume products — custom magnet tooling rarely amortizes across a machine run, and stock parts make the customer's spares problem trivial; the math is in the MOQ & lead-time guide
design for the ±3–5% lot window
holding margins, sensor thresholds, and coupling torque all see normal lot spread — commission with margin so field units match the demo unit
06
Safety around automation
- Powered motion + strong magnets = amplified pinch hazards. A hand near a magnetic gripper on a moving axis faces both the machine's force and the magnet's grab — risk-assess magnet stations explicitly, and guard reach-in zones accordingly.
- Failure of holding is a projectile or a dropped-part hazard: magnetically held parts over walkways, operators, or fragile equipment need the redundant-retention rule — mechanical capture backing the magnetic hold, and drop zones inside guarding.
- Fields and the people around the machine: strong-field zones marked for pacemaker and implant wearers — commissioning crews and maintenance techs included, not just operators; keep the warnings in the machine documentation.
- Fields and the machine's own electronics: route magnetized elements away from encoders, magnetic scales, reed-based interlocks, and mag-stripe/RFID readers — and remember service scenarios where a removed magnet travels past them.
- Maintenance-mode hazards belong in the manual: stored magnetic energy doesn't lock out. De-energizing the machine leaves every permanent magnet at full strength — a fact worth a line in the LOTO-adjacent documentation.
07
The machine BOM & the customer's spares list
- Every magnet gets a real part number — size, grade, direction, coating, and source — on the BOM and in the manual. “Magnet, misc.” on a machine BOM is a future service call you'll eat.
- Spec acceptance where it matters: for sensing targets and couplings, a field-at-point or moment requirement per the testing guide makes the replacement predictable; for holding duty, size and material usually suffice.
- Ship the spares story with the machine: recommended spares list with stock-size magnets the customer can reorder in days, wear-item designation for conveyance faces, and the target-magnet warning from section 03 in the maintenance chapter.
- Protect your build schedule: machine projects buy magnets in small odd quantities on tight timelines — exactly the profile U.S. stock serves; put the long-lead customs (if any) on the project plan the week the concept freezes, per the lead-time guide.
- Freight the machine correctly: a machine full of strong magnets can itself trip air-freight field limits — the UN 2807 rules apply to the crated machine, not just loose magnets, and the fix (shielding, measurement docs, or ocean) is cheaper planned than discovered at the forwarder.