Key Takeaways
- Castable SLA resin masters printed for gold jewellery.
- Crisp detail and clean burnout for investment casting.
- Cut cost and time versus hand-carving.
- Enabled fast design iteration for jewellers.
Background
A Surat-based jewellery manufacturer producing 22K gold jewellery for the domestic and export market relied on CNC-carved wax patterns for their investment casting operation. Each wax pattern — the positive model from which the casting mould is made — was CNC machined by a specialist wax carver at ₹800–2,500 per piece for complex designs, with 10–14 day lead times and a minimum order of 5 units per design.
The manufacturer's design team was developing a new product range with 40+ distinct SKUs for a seasonal collection. The pattern cost for the full collection would be ₹48,000–80,000 in CNC wax, plus 10–14 weeks of lead time staggered across the range. The timeline did not support the sales season launch. The production manager contacted Layer X in Ahmedabad after seeing a trade article on SLA castable resin for jewellery manufacturing.
Technical Requirements
- Wax-out performance: Zero ash residue at 750°C burnout (standard investment casting burnout cycle) — any residue contaminates the gold casting
- Surface finish: Smooth enough to accept investment slurry coating without surface artefacts transferring to final casting — Ra <2.0 µm on external surfaces after post-cure
- Dimensional accuracy: ±0.05 mm on critical dimensions (ring bore diameter, stone seat diameter)
- Sprue attachment: Patterns must accept standard wax sprue attachment (wax pen bonding)
- Design complexity: Pierced lattice designs, pavé stone seats, and textured surfaces at 0.3–0.5 mm feature resolution
Process: DICOM to Cast Pattern
Design File Format
The jewellery designer submitted Rhino 3D (.3dm) files. Layer X converted to STEP for slicing after repair in Materialise Magics (fixing non-manifold edges common in jewellery CAD). Design review confirmed all features met SLA minimum resolution requirements (0.2 mm for lattice elements, 0.5 mm for stone seat walls).
SLA Process for Castable Resin
Formlabs Castable Wax 40 resin was used — the industry standard for gold casting patterns. Print parameters: 0.025 mm layer height (finest available, required for stone seat detail), Form 3 SLA printer. Build time: 4–6 hours per batch of 12–15 pendants or 20–25 rings depending on size and orientation. Post-cure: UV cure station 60°C × 30 minutes (per Formlabs protocol for castable resin — deviation from protocol affects burnout performance).
Quality Check Before Casting
Layer X performed visual inspection under 10× magnification on the first batch — stone seat geometry, lattice element integrity, and overall surface quality. CMM spot-check on ring bore dimensions (confirmed ±0.03 mm, within 0.05 mm tolerance). One design had a 0.18 mm lattice element that was borderline — the designer was consulted and the element was thickened to 0.25 mm for the production run.
Customer's Casting Process
The Surat manufacturer's casting team sprued, invested in Prestige Hi-Temp investment (450 g/250 ml water ratio), and ran a standard burnout cycle (150°C → 350°C → 730°C ramp, 1h hold, casting). Zero ash contamination — castings released from investment cleanly. Gold finishing team reported surface texture on castings equivalent to CNC wax patterns after polishing.
Results
| Metric | CNC wax patterns | SLA castable resin (Layer X) |
|---|---|---|
| Cost per pattern (complex pendant) | ₹1,800–2,500 | ₹95–140 |
| Cost per pattern (standard ring) | ₹800–1,200 | ₹45–80 |
| Full 40-SKU collection cost | ₹48,000–80,000 | ₹3,200–5,600 |
| Lead time (5-piece minimum batch) | 10–14 days | 48–72 hours |
| Minimum order quantity | 5 per design | 1 per design |
| Design modification cost | Full recarve: ₹800–2,500 | File change: Zero |
| Casting quality | Reference standard | Equivalent (confirmed by casters) |
The 40-SKU collection was produced in three SLS batches over 5 days at ₹4,200 total pattern cost — a 94% reduction from the CNC wax baseline. The manufacturer launched the collection 6 weeks ahead of the original timeline. Three designs required modifications after the first casting evaluation — changes were implemented and re-printed within 24 hours at ₹95–140 per revised pattern. Total project savings versus CNC wax route: ₹74,000 on pattern cost alone, plus ₹1.8 lakh in estimated revenue from early collection launch.
Layer X provides SLA castable resin patterns for gold, silver, platinum, and bronze investment casting. Serving jewellery manufacturers in Surat, Mumbai, and across India. Send your Rhino or Matrix files for a same-day quote.