Arc Magnet 研削 機械
The VMG-490 is a 4-station pass-through arc magnet grinding machine that finishes the inner arc, outer arc, or end faces of tile-shaped permanent magnets at up to 20 pieces per minute. Workpiece envelope is 10–70 mm long × 10–90 mm wide. It's built for permanent magnet motor production lines — EV traction, servo, blower, audio — where reload time on single-station grinders is the bottleneck.
The design priority is throughput without losing arc tolerance. Four grinding stations sit on one continuous conveyor; the part is clamped at infeed and stays clamped through all four stations until it drops off the outfeed. No reclamp, no realign, no secondary fixturing.
Where the VMG-490 is in production
The machine is in production across the following workpiece classes. If your tile is outside the 10–70 × 10–90 mm envelope — bigger wind-turbine segments, for example, or sub-10 mm sensor magnets — this isn't the right answer.
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A.01EV traction motor rotor magnets
Sintered NdFeB tiles, typical arc length 30–55 mm, thickness 5–10 mm, grades N42UH to N52H. Used in IPM and SPM rotor architectures.
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A.02Servo & machine-tool spindle motors
Sintered or bonded NdFeB tiles, smaller arc (15–25 mm), tighter R tolerance. The 4-station setup matters here — rough + finish on the same arc face in one pass.
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A.03HVAC, blower & compressor motors
Sintered ferrite (hard ceramic) tiles, arc length 40–70 mm. Cost-driven applications where wheel wear rate dominates the operating budget.
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A.04Audio drivers & speaker assemblies
Ferrite arc segments, 30–50 mm. High-volume production where 20 pcs/min throughput is the line target.
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A.05Power tool & small appliance motors
Sintered NdFeB, smaller tiles (10–20 mm arc). Often run alongside larger automotive parts in the same shift; parameter recall handles the changeover.
Spec sheet
| Configuration | 4-station pass-through, in-line |
| Workpiece length range | 10 – 70 mm |
| Workpiece width range | 10 – 90 mm |
| Throughput | Up to 20 pcs/min (≈ 1,200 pcs/h) |
| Arc tolerance (R) | ±0.03 mm |
| Grinding head spindle motor | 7.5 kW × 2 |
| Pneumatic clamping clearance | 0.01 mm |
| In-feed servo motor (per station) | 0.75 kW × 4 |
| Wheel-dressing motor | 1.5 kW × 2 |
| Conveyor belt size | 1920 × 100 × 3 mm |
| Conveyor drive motor | 0.3 kW high-frequency motor with gear reduction |
| Feed speed (variable) | 0.2 – 3 m/min |
| Coolant / lubrication | Glycol-ester base + corrosion inhibitor |
| Frame construction | Welded steel-frame bed, sheet-metal enclosure |
| Compatible materials | Sintered NdFeB · Bonded NdFeB · SmCo · Hard ferrite · AlNiCo |
| Auto loading / unloading | オプション |
How the arc magnet grinding machine works
Pass-through grinding works differently from oscillating cup-wheel grinders or single-station double-end face grinders. The workpiece sits on the conveyor at infeed, is clamped pneumatically against a reference rail, and travels under four grinding stations in sequence. By the time it reaches outfeed, the arc face is fully ground to spec.
Two of the four stations carry 7.5 kW spindles. These are the heavy material-removal stations — typically the rough-grind on the inner arc and the rough-grind on the outer arc. The remaining two stations handle finish-grind passes with smaller in-feed depth, or in some configurations, end-face grinding to set the arc length dimension.
Each station has its own 0.75 kW in-feed servo. That matters because rough and finish stations need different in-feed depths on the same workpiece. With independent servos, you tune rough at, say, 0.15 mm/pass and finish at 0.02 mm/pass without disturbing the conveyor speed. On a single-station machine you'd have to change wheels (or change the whole job setup) between rough and finish — that's where the 20 pcs/min throughput comes from.
The conveyor runs at 0.2–3 m/min, set by the production parameter for the material grade. Sintered N52 NdFeB at 8 mm thickness typically runs around 1.5 m/min; ferrite at 12 mm thickness drops to 0.6 m/min because of wheel wear pacing. Pneumatic clamping at 0.01 mm clearance keeps the part flat against the rail through all four stations.
Upstream of this machine the typical workflow is: NdFeB block → multi-wire saw → tile blanks at 0.18–0.25 mm kerf → VMG-490 grind to spec → chamfering → polishing → plating. Each of those steps belongs to a different machine; the VMG-490 covers the arc/face grinding step.
Material guide
The VMG-490 handles the full range of permanent magnet materials in tile form. Wheel selection and feed rate change with material — the machine itself is material-agnostic.
| 素材 | Compatibility | 備考 |
|---|---|---|
| Sintered NdFeB | ✓ Primary application | Diamond / CBN wheel; reduce feed for grades > N50; flood coolant mandatory to keep local heat below ~60 °C and protect magnetic properties. |
| Bonded NdFeB | ✓ Compatible | Slow feed; resin matrix degrades above ~80 °C — coolant flow is non-negotiable. |
| SmCo (Sm₂Co₁₇ / SmCo₅) | ✓ Compatible | More brittle than NdFeB. Reduce in-feed depth per pass to avoid edge chipping. Expensive scrap, so run-in carefully on a new wheel. |
| Sintered hard ferrite | ✓ Compatible | Wheel wear is 3–5× faster than on NdFeB at the same removal rate. Plan dressing intervals shorter. |
| AlNiCo | ✓ Compatible | Less common in tile form, but compatible. Cast structure can grab on the wheel — verify clamping force before running production. |
Not recommended
- Flexible bonded magnets (rubber-bonded, nylon-bonded sheet) — these are die-cut, not ground.
- "Green" un-sintered rare-earth pressed blanks — wait until after sintering. Grinding green parts produces dust, not chips, and dimensions won't hold.
For NdFeB grade definitions, see the IEC standards on hard magnetic materials at webstore.iec.ch (IEC 60404-8-1 covers sintered rare-earth magnets).
What makes the design hold up under production load
Four independent grinding stations on one belt
Single-station grinders force you to reclamp the part 3–4 times to hit all the surfaces. Each reclamp adds 20–30 seconds of cycle time and introduces alignment error that shows up as ±0.05 mm or worse R variation between batches. The VMG-490 keeps the part clamped from infeed to outfeed — four stations work the same workpiece in sequence without releasing it.
This is the single biggest difference between 4-station throughput (20 pcs/min) and single-station throughput (4–6 pcs/min) on identical parts.
0.01 mm pneumatic clamping clearance
Clamps that drift more than 0.02 mm during the grind cycle let the same workpiece see different removal depths at different stations. The fixed 0.01 mm pneumatic clearance is what holds the ±0.03 mm arc tolerance across all four stations.
It's also what keeps tolerance stable shift-to-shift. Air pressure and clamp wear are the usual drift sources; pneumatic is more repeatable than mechanical spring clamps over 8-hour runs.
Two on-board wheel-dressing motors (1.5 kW × 2)
Ferrite chews wheels fast. Without on-machine dressing, you stop the line and re-true the wheel on a separate fixture — production sites lose 45 minutes per shift to off-machine dressing on ferrite-heavy schedules. On-board dressers re-profile in under 2 minutes between batches, and they can re-true the wheel without breaking down the setup.
Surface finish stays predictable on long runs. A glazed wheel doesn't fail catastrophically — it slowly drifts. Inline dressing catches the drift before parts go to chamfering.
Glycol-ester coolant with corrosion inhibitor
NdFeB rusts within 30 minutes of grinding if you use an unmodified water-based coolant. By the time the parts reach chamfering or plating, the freshly ground surface is already degraded. The glycol-ester blend wets the cutting interface, carries grinding heat away, and leaves a thin corrosion-inhibitor film.
That's the difference between a clean substrate for nickel plating and a re-cleaning step before the plating tank. 24-hour transit time becomes safe.
Welded steel-frame bed
At 20 pcs/min with two 7.5 kW spindles running, vibration shows up directly in arc tolerance. A welded steel frame absorbs grinding force and damps spindle harmonics passively. The sheet-metal panels you see are enclosure only — chosen for serviceability and cost. The structure under them is what carries the load.
An earlier prototype on a stamped-frame base opened up to ±0.06 mm under sustained load. The welded frame brought it back inside ±0.03 mm with no change to spindles or wheels.
Variable feed 0.2–3 m/min
Sintered N50 NdFeB at 8 mm thickness needs a different feed than ferrite at 12 mm thickness. Production lines that switch grades every shift need infinitely variable feed — a 5-step gearbox isn't enough. The VMG-490 covers the full range with parameter recall.
A grade changeover is a screen press, not a setup change. Same machine handles N35 to N52H, ferrite to SmCo.
Modular add-ons
| Module | What it does | When to specify |
|---|---|---|
| Auto loader / unloader | Vibratory bowl or robotic infeed + outfeed conveyor to bin | Lights-out shifts, >2 shifts/day, or high-cost magnet grades where operator handling risks scrap |
| Inline thickness gauge | Laser displacement sensor at infeed; rejects parts outside ±0.1 mm pre-grind tolerance | Mixed-supplier blanks where as-cut variation is wide |
| Magnetic chip / coolant separator | Drum or belt magnetic separator with paper polish filter | NdFeB-heavy production; mandatory for ISO 14001 closed-loop coolant sites |
| Wheel-monitor add-on | Acoustic emission sensor with wear-rate alert | Long unattended runs; catches wheel glaze before scrapping a batch |
| Pre-trued profile wheels | Spindle-mount diamond / CBN profile wheels matched to your tile R | Specify R range and bond at order — we ship pre-trued |
| Coolant chiller | Closed-loop cooling to hold coolant at 18–22 °C | Hot climates, or NdFeB grades sensitive to thermal aging |
Questions engineers ask before buying
Can the VMG-490 grind 50 × 30 × 8 mm sintered NdFeB tiles for a 48V drive motor?
Yes — that part sits well inside the 10–70 mm length × 10–90 mm width envelope, and 8 mm thickness is comfortable for a four-station pass. For an N48H grade with no surface coating, expect throughput around 18–20 pcs/min and one wheel dressing per ~2,000 pieces. Send the tile drawing and material grade with your inquiry — we'll specify the matching wheel pair (rough + finish) and quote lead time.
What's the difference between this machine and a double-end face grinder?
Different jobs, not interchangeable. A double-end face grinder grinds the two flat faces of a magnet — fast, but only those two surfaces. The VMG-490 grinds the curved arc faces (and optionally the end faces) on tile-shaped magnets. For a typical EV rotor tile you'd run the part through both machines: arc faces on the VMG-490, then thickness on a double-end face grinder.
They're complementary, not substitutes. A 4-station pass-through arc magnet grinding machine occupies about 4 m of floor length; a double-end face grinder is closer to 1.5 m.
How much grinding wheel do I burn through running ferrite vs. NdFeB?
Roughly 3–5× faster wheel wear on hard ferrite at the same material removal rate. Ferrite hardness is comparable to NdFeB but the abrasive grain pulls out more easily on ferrite, so wheels glaze and need re-dressing sooner. Plan the dressing schedule around the dominant material in your batch — and don't run NdFeB and ferrite back-to-back on the same wheel without re-dressing in between, or you'll get inconsistent finish on both.
Is auto loading / unloading included or is it a separate option?
It's optional. The base machine ships with manual load at the infeed and a gravity outfeed chute to a parts bin. Most customers running two or three shifts add the auto loader — operator handling risk on high-grade NdFeB is real. Single-shift operations often run manual to save on capital expenditure and add the loader later. The conveyor is built to mate with downstream automation, so retrofit is straightforward.
What surface roughness (Ra) can this arc magnet grinding machine achieve?
Ra is set by the wheel you specify, not the machine. With a fine-grit resin-bond diamond finishing wheel (#400 grit or finer), customers report Ra 0.4–0.8 µm — within the typical range for nickel or zinc plating prep without an additional polishing step. Coarser rough wheels for stock removal will leave Ra 1.6 µm or higher, and that's where downstream polishing fits in. Tell us your plating spec at quote time and we'll recommend the wheel pair.
For surface-roughness measurement standards, see ISO 21920-2.
What's the typical lead time and what's included in commissioning?
Standard configuration ships in 60–90 days from purchase order. Commissioning at the customer site includes uncrating, levelling, coolant fill, wheel mounting and truing, control-system parameterization, first-article validation against your tile drawing, and operator training (typically 3–5 days on-site). We don't sign off until acceptance criteria are met against the drawing — not against a generic spec sheet.
How does parallelism hold up over a long production run?
Across the customer base running this machine, parallelism on the ground arc faces stays within drawing spec — the welded frame and pneumatic clamping handle the structural side, and the on-board dressers handle wheel drift. The variable that matters most for parallelism is incoming blank flatness; if your multi-wire-saw output has thickness variation > 0.1 mm, that propagates downstream regardless of how well the grinder holds tolerance. The optional inline thickness gauge catches that at infeed.
Send the drawing. We'll quote in 48 hours.
Send your tile drawing and material grade — sintered NdFeB N-grade, ferrite Y-grade, or SmCo composition — along with required throughput and surface finish target. We'll quote the wheel pair, fixturing, and lead time.
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