Outline & Topics Covered
- Understanding the Lost Wax Casting Process
- Prong Heights and Stone Setting Tolerances
- Wall Thickness Minimums to Prevent Casting Porosity
- Casting Shrinkage Calculations
From Digital Design to Physical Castings
Lost wax casting involves 3D printing a design in castable resin, placing it inside a flask, surrounding it with plaster investment, burning it out in a kiln, and injecting molten gold or silver. To prevent casting failures, your digital models must respect physical manufacturing boundaries.
Prong and Setting Tolerances
Prongs should never be designed at their final height. As metal cools and is polished, it wears down. Always add an overlength of 0.3mm to 0.5mm to your prongs in CAD. This gives the stone-setter enough material to securely push over the diamond and file a clean, polished bead.
Wall Thickness Minimums
If walls are designed thinner than 0.7mm, molten metal will cool too quickly during injection. This blocks the metal flow, causing incomplete fills and structural porosity. Maintain a wall thickness of 0.8mm to 1.0mm for standard commercial rings and pendants.
Curing and Shrinkage
Castable resins shrink slightly during print curing and metal cooling. Designing your CAD files with a 1.5% to 2.5% scale expansion compensates for this shrinkage. Our library models are pre-calibrated to account for standard shrinkage rates, ensuring they cast at their correct target weights.