How to Prepare an RFQ for Custom Magnets

A custom magnet quote is only as accurate as the specification behind it. When an RFQ arrives missing the magnetization direction, the operating temperature, or the tolerance scheme, the supplier has two options: guess, or ask. Guessing produces a quote you can't rely on. Asking adds a round-trip — often several — before pricing even begins.

A complete RFQ does three things for you:

• Faster turnaround. Quotes on complete specs typically return in 1–3 business days. Incomplete RFQs routinely take one to two weeks of back-and-forth.
• Better pricing. When a supplier can see exactly what is — and is not — critical, they can quote against your real requirements instead of padding for uncertainty.
• Fewer downstream surprises. Specification gaps discovered at PPAP or first article are the most expensive kind. Closing them at RFQ costs nothing.

Provide a dimensioned drawing whenever possible — PDF, DXF, or STEP. If a drawing doesn't exist yet, a fully dimensioned sketch with every feature called out is acceptable for budgetary quoting.

What to specify

• All physical dimensions — OD, ID, thickness/length for rings and discs; L × W × H for blocks; chamfers and radii if required.
• Tolerances on each dimension. Standard machining tolerance for sintered NdFeB is ±0.05 mm (±0.002"). Specify tighter tolerances only where the application demands them.
• Units. State metric or imperial explicitly and use one system throughout the drawing.
• Critical characteristics. Flag which dimensions are functionally critical (fit, air gap) versus reference. This is where the largest cost savings hide.

Sintered NdFeB is a brittle powder-metallurgy ceramic-like material — it is ground to size, not cut like steel. Sharp internal corners, very thin walls (under ~1 mm), and length-to-diameter ratios above ~8:1 all raise cost and scrap risk. If your geometry has any of these features, say so and ask the supplier whether a small change would reduce price.

There are two valid ways to specify magnetic material, and both work — pick the one that matches how far along your design is.

Option A — specify the grade directly

If your design is proven, call out the full grade including temperature class: for example N42SH, not just "N42" or "neodymium." The letter suffix defines the intrinsic coercivity (resistance to demagnetization at temperature) and drives a large share of material cost because higher classes use heavy rare earths.

*Ratings assume a favorable permeance coefficient; actual limits depend on the magnetic circuit. See section 06.

Option B — specify the requirement, not the grade

If you're earlier in design, state the performance you need and let the supplier propose the grade: required flux density at a defined point or air gap, maximum operating temperature, external demagnetizing fields, and space envelope. A good supplier will often find a lower-cost grade that meets the requirement.

Magnetization direction must appear on the drawing — as an arrow, a note, or both. Sintered NdFeB is anisotropic: the direction is fixed when the powder is pressed in a magnetic field, long before final magnetization. The wrong direction cannot be fixed after manufacture; the parts are scrap.

Specify one of the following

• Axial — through the thickness (discs, rings, blocks through the smallest dimension is "through thickness"; state which axis).
• Diametric — across the diameter of a disc, ring, or cylinder.
• True radial — flux oriented along the radius, uniform around the full circumference of a ring. Requires specialized pressing and magnetizing capability; not equivalent to a segmented assembly.
• Multipole — specify pole count, pole placement (OD, ID, or face), and whether poles are on one face or both.

For multipole parts, also state the required pole-to-pole uniformity and how you will measure it (e.g., surface field scan). This determines whether standard magnetizing fixtures are adequate or custom tooling is required.

Uncoated NdFeB corrodes — quickly in humidity, immediately in salt spray. Coating selection is a real engineering decision, so give the supplier the environmental context along with (or instead of) a coating callout.

Environmental details to include

• Humidity exposure, immersion, or washdown
• Salt spray requirement, if any (hours per ASTM B117)
• Chemical exposure — solvents, fuels, sterilants, body fluids
• Whether the magnet will be adhesive-bonded (affects coating choice)
• Cosmetic requirements, if the magnet is visible in the product

Two magnets with identical drawings can have completely different grade requirements depending on how they're used. Give the supplier the conditions the magnet actually lives in:

• Maximum continuous operating temperature, plus any short excursions (reflow soldering, sterilization cycles, cure ovens).
• Minimum temperature if below −40 °C (relevant for some coatings and adhesives).
• External demagnetizing fields — opposing magnets, stator currents, magnetizing/degaussing equipment nearby.
• The magnetic circuit — open air, on a steel backing plate, or in a closed circuit. This sets the permeance coefficient, which determines how much temperature the magnet can actually tolerate before irreversible loss.
• Mechanical loads — press-fit stress, shock, vibration. Sintered NdFeB is strong in compression but weak in tension and bending.

Magnet pricing is strongly volume-dependent because setup, tooling, and magnetizing fixture costs amortize across the order. Give the supplier enough commercial context to quote the right tiers:

• Prototype quantity and when you need it.
• Estimated annual usage (EAU) once in production — even a rough range changes the quote structure.
• Quantity breaks you want quoted — e.g., 100 / 1,000 / 10,000 / 50,000.
• Target price, if you have one. Suppliers can often propose a spec change to hit a number if they know what the number is.
• Delivery terms — Incoterms, destination, and whether you need domestic stocking or scheduled releases.
• Program timeline — samples, PPAP/qualification date, start of production.

For a full breakdown of what drives each line of a magnet quote — raw materials, grade premiums, machining, coating, tooling — see our companion guide, Magnet Pricing Explained.

Documentation requirements affect both price and lead time, so state them up front rather than after award:

If you need incoming-inspection criteria, define the magnetic acceptance test in measurable terms: "total flux per helmholtz coil ≥ X µWb" is enforceable; "strong magnet" is not.

Copy this into your RFQ document or email. If every box is checked, your quote will come back fast and firm.