SRS - Technical Centre: Helpful Hints

1. The finished casting will never be better than the model. The time spent preparing the model will be repaid in the quality of the casting made from it.

2. Often a compromise may have to be made in a jewellery design to improve its castability. A small modification in design can mean the difference between a 50% scrap factor and a 1% scrap factor. Casting defects have been designed into a model, due to a lack of knowledge in the behavior of molten metals.

3. Try to visualise how molten metal will flow through a given design and if it will solidify evenly. This will allow design modifications to make the design more castable.

4. Thin to thick sections can be problem areas subject to cracks, hot tears and shrinkage porosity. This area will solidify before thick areas causing stress points that may crack on quenching or during finishing. Shrinkage porosity can also occur in the heavier areas due to the shut off of molten metal supply when thin areas solidify first.

5. Round out sharp angles in the model as the tips of the angles can tear off in the rubber moulds or break off during casting causing inclusions in the casting.

6. Remove file marks, rough edges and pinholes in the model as these defects will follow through to the finished casting.

7. Rhodium plating of the model will prevent tarnishing during the vulcanisation of the rubber.

View other helpful hints online or download (Acrobat Reader PDF) versions by selecting relevant links below:

HELPFUL HINTS

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	Wax Patterns		Download PDF (124k)