Shell moulding is also similar to sand moulding except that a mixture of sand and 3 - 6% resin holds the grains together. Set-up and production of shell mould patterns takes weeks, after which an output of 5-50 pieces/hour-mould is attainable.

Aluminium and magnesium products average about 13.5 kg as a normal limit, but it is possible to cast items in the 45-90 kg range. Shell mould walling varies from 3-10 mm thick, depending on the forming time of the resin.

There are a dozen different stages in shell mould processing that include:

  1. initially preparing a metal-matched plate
  2. mixing resin and sand
  3. heating pattern, usually to between 505-550 K
  4. inverting the pattern (the sand is at one end of a box and the pattern at the other, and the box is inverted for a time determined by the desired thickness of the mill)
  5. curing the shell and baking it
  6. removing investment
  7. inserting cores
  8. repeating for the other half
  9. assembling the mould
  10. pouring the mould
  11. removing casting
  12. cleaning and trimming

The sand-resin mix can be recycled by burning off the resin at high temperatures