Bridge tooling sits between prototype and full production. Aluminum 7075 mold inserts (or full aluminum mold bases for smaller parts) produce 30,000-50,000 parts before wear becomes problematic. 3-4 week build, $4,200-12,000 typical cost. Ideal for product launches, market validation, and bridging the gap while production steel tooling is being built.
Prototype tooling (P20 steel, 2-3 weeks) handles up to 10,000 shots before degrading. Production tooling (H13 steel, 5-7 weeks, $15K+) handles 1M+ shots but is too expensive and slow for market validation.
Aluminum bridge tooling fills this gap:
Bridge tooling is genuinely faster to cycle than steel — aluminum conducts heat ~5× better than H13 steel, so mold temperature equilibrates faster and cooling time drops 15-25%. Counter-intuitively, a good bridge tool can produce more parts per day than a steel tool of the same geometry.
You plan to order 500,000 units over the product's life, but the first 10,000 sell-through tells you whether it's worth the production tool. Bridge tool saves $10K if the market doesn't materialize.
Production tools take 5-7 weeks. Meanwhile you need parts to ship. Bridge tool covers the gap, then retires once production is live.
If total lifetime volume is 10,000-30,000 units, bridge tooling may be all you ever need. No production tool investment required.
Above 100K units per year, bridge tool wears out multiple times. Production steel is cheaper per-part.
Glass-filled nylon (PA66-GF30+), PEEK, LCP all eat aluminum tooling fast. Bridge tool life drops to 2,000-5,000 shots. Use steel.
Aluminum doesn't hold a mirror polish through 10K+ cycles. For SPI A-series finishes, use S136 steel.
| Aspect | Prototype (P20) | Bridge (7075-AL) | Production (H13) |
|---|---|---|---|
| Material | P20 pre-hardened steel | 7075-T6 aluminum (hard-anodized) | H13 hardened steel |
| Hardness | 32 HRC | ~52 HRC equivalent (anodize) | 52 HRC |
| Shot life | 10,000 | 30,000-50,000 | 1,000,000+ |
| Lead time | 14-21 days | 21-28 days | 35-49 days |
| Cost (typical) | $2,800-8,000 | $4,200-12,000 | $8,500-50,000+ |
| Cycle time | Baseline | -15 to -25% | Baseline |
| Cavity count typical | 1 | 1-2 | 2-16 |
| Hot runner | No | Rare | Standard |
| Surface finish | SPI B1-B3 | SPI B series | Full range A-D |
| Tool modifications | 2 included | 1-2 included | Per quote |
Bridge tooling handles most unfilled and lightly-filled thermoplastics. Abrasive fillers cut shot life dramatically:
| Resin | Bridge tool life | Notes |
|---|---|---|
| ABS, PS, PE, PP (unfilled) | 40,000-50,000 shots | Full bridge-tool range achievable |
| PC, PC/ABS, POM | 30,000-40,000 shots | Slightly abrasive but fine |
| PA6, PA66 (unfilled) | 25,000-35,000 shots | Higher mold temperature stresses tool |
| TPE, TPU, SBS | 40,000+ shots | Low wear |
| PA6-GF15 (15% glass) | 10,000-15,000 shots | Glass abrades aluminum |
| PA66-GF30+ (30%+ glass) | 2,000-5,000 shots | Not recommended for bridge |
| PEEK, LCP | Not recommended | Use H13 or SKD11 steel |
Bridge tooling workflow is streamlined vs full production:
Same rigor as production tooling. Draft angles, wall uniformity, ejection plan, gate location reviewed.
Tool design is simpler than production — single cavity, basic hot runner usually skipped, conventional ejection.
7075-T6 machines 4-5× faster than hardened H13. Single-setup 5-axis machining where possible. Surface polishing before hard-anodizing.
Hard anodize layer (Type III) hardens the tool surface to ~52 HRC equivalent. Critical for abrasion resistance. Adds ~40 μm of anodize thickness — accounted for in machining dimensions.
First shots produced, samples shipped. Dimensional and cosmetic review.
Minor revisions handled in-house. Welding or major modifications are difficult on aluminum — better to live with minor issues or rebuild.
Upload your STEP. We quote bridge tool based on projected volume, target shot life, and resin. Typical turnaround: 21 days to parts in hand.
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