Magnets on the NPI Timeline

Why magnets go critical-path

• Custom tooling is the long pole: pressing dies and magnetizing fixtures front-load the first order — and design changes after tooling reset the clock. The timelines are laid out in the MOQ & lead-time guide.
• The process is batch physics: furnace campaigns, plating batches, and magnetizing runs don't compress on demand — expedites buy freight time, not furnace time.
• Policy adds a permitting clock: rare earth export licensing and tariff changes inject calendar risk that has nothing to do with your supplier's diligence — the mechanics are in the tariffs & landed cost guide.
• Qualification is serial: production tooling → FAI parts → your validation testing → corrections → re-FAI if needed. Every step needs real parts from the real process, which is why the magnet's schedule starts earlier than its size suggests.

The prototype trap

Prototype magnets and production magnets are different products wearing the same drawing, and three gaps between them ambush programs at validation:

• Process gap: prototype parts are often machined from oversized blanks or hand-finished — different surface condition, different edge quality, sometimes different material lot behavior than pressed-to-shape production parts. Function usually transfers; tolerances, chip behavior, and coating performance often don't.
• Selection gap: sample lots get picked from the middle of the distribution. Production delivers the whole ±3–5% window — a device calibrated around golden samples meets the full spread at ramp, in front of customers. Design margin for the window (the architecture advice in the sensor guide), or plan sorted supply deliberately.
• Pattern gap: prototype magnetization on a lab fixture and production magnetization on production tooling can differ in pole placement and transition sharpness — which is signal for any sensing product. Validation data on lab-magnetized parts is provisional until production-fixture parts confirm it.

Two prototype-phase accelerators worth knowing: stock sizes cover a surprising share of proof-of-concept needs from U.S. inventory in days, and the sintered vs. bonded decision is cheapest to explore before any tooling exists.

Gate by gate: what to lock when

The highest-leverage single event on this timeline is the supplier DFM review between design freeze and tooling release: which tolerances drive cost, what can't be measured as written, whether a stock size or simplified geometry gets there without tooling — ten minutes of markup versus a re-tooling cycle later.

Tooling & long-lead planning

• Line-item the tooling — pressing die, magnetizing fixture, and any test fixtures — with cost, lead time, and ownership on the PO. Amortized-in-piece-price tooling is invisible on the schedule and contested in every future negotiation.
• Ownership and release rights in writing: you paid for it, you own it, it's released on request — the clause that makes a future second source possible at all, per the second-sourcing guide.
• Sequence the fixture chain: the magnetizing fixture needs the final magnet design; the test fixture needs the magnetizing fixture's output; your validation needs the test fixture. Serial by nature — plan it as such.
• Order FAI + validation + pilot quantities on the first tooling order. A second small lot later re-enters the batch queue; one slightly larger first lot is nearly free by comparison, per the batch economics in the MOQ guide.
• Add policy buffer to import legs: licensing and customs variance belongs in the schedule contingency for any China-touching supply chain, not in the discovery phase.

Qualification on the schedule

• FAI from production tooling and process — every drawing characteristic plus the magnetic acceptance property, measured in the fixture that will run production. Hand-finished samples qualify nothing; this is the gate where that rule bites schedules.
• Retain and distribute the reference hardware: measured FAI samples become the shared standard for supplier and incoming fixtures — budget parts for both sides. The full documentation chain (CoC → material certs → FAI → PPAP-style change control) is in the documentation guide.
• Put the change-management commitment in place before ramp: no site, material, or process change without notice — the clause is free at qualification and unobtainable during a supply crunch.
• Schedule the re-FAI triggers into the program's future: tooling rework, site moves, and coating-line changes each re-open qualification; a program that knows this budgets it instead of absorbing it as a surprise stop-ship.
• Temperature-critical parts get a baked verification set — one afternoon that catches a temperature-class problem before it's a fielded-product problem.

Ramp: from samples to lots

• Expect the full property window. The first production lots deliver the spread the samples didn't. If yield dips as lots arrive, check whether the design is rejecting conforming variation before opening a supplier case — the distinction that keeps ramp reviews factual.
• Run incoming per the plan from day one: AQL scheme on the PO, fixtures correlated against reference hardware, paperwork checked before parts. Ramp is precisely when substitutions and documentation shortcuts slip through, because everyone is in a hurry.
• Watch the supplier's early signals: lead-time quotes stretching, releases slipping, documentation getting sloppy — ramp is also when a supplier discovers whether they actually have the capacity they sold. The scorecard axes from the qualification guide apply from lot one.
• Convert the expedite habit into a reorder policy: reorder points sized to quoted lead time + licensing/customs variance + reaction time. The programs that fly parts every quarter are the ones that skipped this sentence.

De-risking the launch

Before the program team disbands, leave the product with a continuity posture — the four forms of supply security from the second-sourcing guide, decided deliberately:

And hand operations the folder: the drawing at its final revision, the FAI report and reference-sample locations, the acceptance criteria, the supplier agreement with its clauses, and the reorder policy. The launch isn't done when the parts ship — it's done when the next person can run the part without archaeology.

Related: MOQs, lead times & tooling · quality documentation guide · RFQ preparation guide