Shell Moulding

ell molding, also known as shell-mold casting, is an expendable mold casting process that uses a resin covered sand to form the mold.Shell moulding is  similar to sand moulding except that a mixture of sand and 3-6% resin holds the grains together. Shell moulding also uses sand with a much smaller grain than green-sand. Set-up and production of shell mould patterns takes weeks, after which an output of 5-50 pieces/hr-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.
Shell moulding is used for small parts that require high precision. Some examples include gear housings, cylinder heads and connecting rods.It is also used to make high-precision moulding cores. Compared to sand casting this process makes complex parts be cast with better dimensional accuracy, a higher productivity rate, and lower labor requirements. less labor.

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 505-550K
 4. Inverting the pattern
 5. Curing shell and baking it
 6. Removing investment
 7. Inserting cores
 8. Repeating for other half
 9. Assembling mould
10. Pouring mould
11. Removing casting
12. Cleaning and trimming.
The sand-resin mix can be recycled by burning off the resin at high temperatures.