1- What Is Lost Foam Casting?
Lost Foam Casting, also called Lost Foam Casting (LFC) or Full Mold Casting, is a kind of Evaporative Pattern Casting (EPC) with dry sand casting process. The EPC is sometimes could be short for Expendable Pattern Casting because the lost foam patterns could be used only once. After the foam patterns are finished by special machined, then the foamed plastic patterns are coated with refractory coating to form a strong shell to withstand the molten metal. The foam patterns with shells are put into the sand box, and fill it with dry sand sand around them. During pouring, the high-temperature molten metal makes the foam pattern pyrolyzed and “disappears” and occupies the exit cavity of the patterns, and finally the finished desired castings are obtained.
2- What Are The Steps of Lost Foam Casting
1- Use foam molds to produce foam patterns and casting gating systems
2- Bond the patterns and runners to form a mold bundle module
3- Dip paint on the module
4- Dry the paint
5- Put the module into the sand box and fill it with dry sand
6- Vibrate molding in order to fill the cavity with dry sand and then compact the molding sand
7- Pouring molten metal to vaporize the foam and then forming the desired castings
8- After the castings have cooled, clean the castings. The dry sand can be recycled
3- What Are the Advantages of Lost Foam Casting?
✔ Greater design freedom for complex structural castings
✔ No draft angle is needed to save lots of cost.
✔ Function integrated foam patterns could be assembled from several pieces of foam patterns.
✔ Lost foam castings are near-net-shape process
✔ High flexibility through short set-up times
✔ Longer EPS mould service lives, hence lower proportionate tool costs
✔ Assembly and treatment costs are reduced by the omission of the treatment process, installation parts, screw connections, etc.
✔ Expansion of the scope of applications
4- What Metals and Alloys Could Be Cast by Lost Foam Casting Process?
• Gray Cast Iron, Ductile Cast Iron
• Carbon Steel: Low carbon, medium carbon and high carbon steel
• Cast Steel Alloys: Low alloy steel, high alloy steel, special alloy steel
• Aluminium and their alloys
• Brass & Copper.
5- What Industries Are The Lost Foam Castings Used For?
Just as mentioned above, the lost foam casting is specially suitable to produce the large and thick-wall castings. They are serving mostly the heavy machineries with the requirements of complex structure of the desired castings.
6- What Casting Tolerances Could be Reached by Lost Foam Casting Process?
Generally speaking, the casting tolerances of lost foam castings are better than sand casting, but worse than shell mold casting and no-bake casting processes. For our foundry, we basically could achieve the following casting grades. But we would like to talk with you the specific castings and then decide what numbers we can provide for you.
✔ DCT Grade by Lost Foam Casting: CTG9 ~ CTG13
✔ GCT Grade by Lost Foam Casting: CTG5 ~ CTG8