From Smithells Metals Reference Book, Eighth Edition
26.1 Casting Techniques [1]
| Investment casting | Full mould | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Equivalent terminology | Lost wax casting Precision casting | Cavity-less casting Lost foam | |||||||||||
| Pattern material |
 | Foamed polystyrene or polyurethane Foamed poly | |||||||||||
| Wax, thermoplastics, frozen mercury | |||||||||||||
| Mould material | Silica base ceramic Slurry + stucco | Silica sand Full mould | |||||||||||
| Binder | Ethyl silicate Magnesium or aluminium phosphate | Usually Na 2SiO 3 or resin (Furane) Lost foam unbounded | |||||||||||
| Size range (kg) | Up to 4.5 except frozen Hg for which up to 45 | Up to 5 000 in iron | |||||||||||
| Scope | Complex shapes and fine detail | One-off castings, e.g. jigs and press tools, complex shapes | |||||||||||
| Alloys cast | High temp Steel Cu base Al base alloys | iron and aluminium castings | |||||||||||
| Surface finish (CLA) | 25 25 125 50 85 50 125 | 60 250 | |||||||||||
| Minimum section for length | |||||||||||||
| 25 mm | 1.5 1.0 1.5 12 | ||||||||||||
| 150 mm | 1.5 1.5 1.5 12 | ||||||||||||
| Dimensional tolerancet [ ] mm | |||||||||||||
| 25 mm | 0.13 0.13 0.13 0.6 | 0.20 | |||||||||||
| 150 mm | 0.38 0.25 0.18 2.5 | 0.61 | |||||||||||
| Labour cost per kg | High | Low | |||||||||||
| Equipment cost per kg | High | Low | |||||||||||
| Mould material cost | High | Polystyrene pattern approximate cost one third that of wood. Low for unbonded. For other see Table 26.2. | |||||||||||
| [ ]The following additional tolerances should be added if dimension chosen crosses parting line:
|
| Ceramic mould casting | Plaster mould casting |
|---|
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