costs represent the upfront investment to produce your specific magnet shape and dimensions. Unlike off-the-shelf magnets, custom magnets require tooling tailored to your geometry and magnetization direction. Tooling costs vary dramatically: a simple rectangular block can be cut from standard stock with minimal NRE ($100-$300), while a complex injection-molded ring requires a hardened steel mold ($3,000-$8,000). This guide explains why sintered vs. bonded magnets have different tooling requirements, breaks down NRE charges (mold/die costs, fixturing, programing), compares wire EDM cutting vs. pressing mold costs, provides cost indices for different shapes, and offers strategies to minimize customization costs in prototyping.
Why Sintered vs. Bonded Magnets Have Different Tooling Requirements
Sintered NdFeB: Magnets are pressed from powder in a die under a magnetic field. The die determines the shape (rectangular, round, trapezoidal). Simple shapes (blocks, discs) require a die cost of $500-$1,500. Complex shapes (arcs with taper, multi-level steps) require a die with sliding punches, costing $2,000-$5,000. The pressing die is made of cemented carbide, lasts for 100,000-500,000 parts, then needs replacement or reconditioning.
Bonded (injection molded): Magnets are injection molded in a plastic injection tool (steel mold). Tool cost is $3,000-$8,000 for a single-cavity mold, $10,000-$20,000 for a multi-cavity (4-8 cavities) production mold. Mold life is 500,000-2,000,000 cycles. Injection molding enables complex 3D shapes but requires higher NRE.
Flexible/bonded (compression molded): Simple compression dies ($500-$2,000) for basic shapes (sheets, strips). No complex geometry possible.
Breakdown of NRE (Non-Recurring Engineering) Charges
NRE charges typically include:
Die/mold design and manufacturing: The physical tool. 60-80% of NRE.
Fixturing: For grinding, slicing, or magnetizing the custom shape. 10-20%.
Programming: For wire EDM, CNC grinding, or inspection (CMM). 5-10%.
Setup: For first article production, including pilot run and PPAP. 5-10%.
Shipping of tooling (if the customer owns the die, it's shipped to them after production).
We itemize NRE charges in our quotation. The tooling remains our property unless the customer pays a tooling ownership fee.
Wire EDM Cutting vs. Pressing Mold Costs
For prototype or low-volume custom shapes, wire EDM (electrical discharge machining) is often cheaper than tooling:
Wire EDM: No die cost. The part is cut from a standard block. Setup $100-$300. Per-part cost: high (due to slow cutting, 1-10 parts/hour). Best for <100 pcs.
Pressing die: High upfront die cost ($1,000-$5,000) but very low per-part cost once tooling is built. Best for >1,000 pcs.
Cost comparison (for a 20x20x10mm arc segment, tolerance ±0.05mm):
| Method | NRE Cost | Per-Part Cost (100 pcs) | Per-Part Cost (5,000 pcs) | Best Volume |
|---|---|---|---|---|
| Wire EDM (no die) | $200 | $12.00 | N/A (too slow) | <100 pcs |
| Pressing die + grinding | $2,500 | $6.50 | $2.80 | >1,000 pcs |
| Pressing die (net shape, no grinding) | $3,500 | $4.50 | $2.20 | >5,000 pcs (if tolerance allows) |
Tooling Cost Index for Different Magnet Shapes
Shape complexity determines tooling cost:
| Magnet Shape | Pressing Die Cost Estimate | Machining Required After Pressing | Relative Tooling Index (vs standard block) |
|---|---|---|---|
| Rectangular block (standard dimensions) | $500-$800 | Grinding all 6 faces | 1.0x |
| Disc (standard OD/ID) | $600-$1,000 | Grinding faces, OD | 1.2x |
| Rectangular with chamfer | $800-$1,200 | Grinding + chamfering | 1.5x |
| Arc segment (120° segment, radius 50mm) | $1,500-$2,500 | Grinding ID/OD, faces | 2.5x |
| Trapezoid (tapered sides) | $2,000-$3,500 | Grinding all 4 sides | 3.5x |
| Multi-step block (stepped cross-section) | $3,000-$5,000 | Grinding steps + faces | 5.0x |
| Injection molded complex 3D shape | $5,000-$15,000 (mold) | None (net shape) | 8.0x-15x |
Frequently Asked Questions
Q: If I order custom magnets, who owns the die/tooling after production?
A: By default, the tooling remains our property. If you require exclusive ownership, we charge an additional $500-$1,500 for the "tooling ownership" fee. You then receive the CAD file and a certification that the tooling is for your exclusive use.
Q: Can I use the same die for different magnet grades (N35 vs. N52)?
A: Yes, the die is geometry-specific, not grade-specific. The pressing process is the same for all sintered NdFeB grades. You can order the same shape in N35, N42, N52, or any grade using the same tooling. No extra NRE for grade changes.
Q: What is the lead time for a pressing die?
A: 3-4 weeks for simple dies (block, disc). 5-8 weeks for complex dies (arc segments, multi-step). We provide expedited service (2 weeks) at 50% extra rush fee.
