The 300-Piece Problem
Custom magnetics pricing is built around setup, not around material. A 300-piece order for a wound component carries the same winding programme, the same first-article inspection and often the same minimum core purchase as a 3,000-piece order, which is why the quoted unit price can look absurd at low volume. The buyer’s job is not to argue the price down; it is to move cost out of the order by changing what is being set up.
Where the Money Actually Goes at Low Volume
| Element | 300 pcs | 3,000 pcs | Comment |
|---|---|---|---|
| Core and wire | 35–45 % | 55–65 % | Material is volume-invariant; its share rises as setup is spread |
| Winding and assembly labour | 20–30 % | 25–35 % | Learning curve applies |
| Setup, programme, tooling amortisation | 20–30 % | 3–6 % | The reason low volume is expensive |
| Test and inspection | 8–12 % | 3–6 % | 100 % hipot is per-unit; first article is per-order |
The lever with the largest range is setup. Everything below attacks it.
Seven Ways to Cut Low-Volume Cost
- Use a platform core and bobbin. A part built on a core size the supplier already runs needs no new mould and no new programme. Ask what platforms they have before the design is frozen.
- Accept a wider, honest tolerance. A 10 % inductance window instead of 5 % can remove a trimming or grading step. Only do this if the circuit analysis shows the wider window is genuinely safe.
- Buy the first article and the pilot lot together. One setup, one inspection report, two deliveries. This is the single most effective move for 100–1,000 pieces.
- Standardise on fewer part numbers. Three similar chokes on three drawings cost three setups; one choke used in three places costs one. This is a design decision, and it is often possible.
- Let the supplier choose the internal construction. Specify the electrical and mechanical envelope, not the winding pattern, unless the parasitics require it. Internal freedom is where a supplier can reuse an existing programme.
- Order annual volume with scheduled releases. Commit to the year, call off quarterly. The supplier amortises setup across the commitment, and your inventory stays low.
- Pay for the tooling separately. A visible tooling line item is often cheaper over the programme than tooling buried in a unit price, and it clarifies who owns the mould.
What Not to Do
- Ask for prototype pricing in production quantity and expect the quote to hold.
- Change the drawing after the first article to “save a little” — the second setup usually costs more than the saving.
- Withhold the annual forecast. Suppliers price risk, and an unknown volume is priced as a small volume.
Related reading
- MOQ, Lead Time and Tooling
- The OEM Development Process
- What Drives Magnetic Component Cost
- Second Source Strategy
We quote low volume honestly, with the setup shown as a separate line so you can see what a larger release would remove. Send the annual forecast and the pilot quantity to sales@sirui-tech.com.