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 machines, 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.
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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 lost foam foundry, we basically could achieve the following casting tolerance 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
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The flask is transported to the pouring operation. The foam is evaporated as the metal is poured allowing the metal to take the shape of the casting cluster. Separation of sand and metal is accomplished at a Flask Dump Station. With no binders in the sand this process is performed with ease. Systems can be designed to accommodate quenching operations if required. The cluster proceeds to the casting finishing area for sprue, gate and riser removal. The sand is reprocessed by classification and cooling to be re-used. Thermal reclamation of the sand will extend the useful life. Lost Foam offers an environmentally friendly process with the added advantage of more accurate casting.
Foam patterns are created from polystyrene beads. The beads start as hard granules, very similar in size and shape to sand granules. The beads are expanded, allowed to stabilize and then molded into the desired shape. More complex shapes require multiple patterns to be glued together. The assemblies are then attached to a generic, central foam piece called a tree. Multiple patterns can be produced on a single tree. After assembly, the entire tree is dipped into a refractory coating to strengthen the tree. The assembled, strengthened tree is attached to a pouring funnel (called a sprue) and placed into the flask.
Vulcan Engineering Co. is recognized as the World Leader in lost foam technology. We provide a comprehensive line of lost foam equipment, including flask pouring, flask handling and flask compaction. Our line of foam bead processing equipment is recognized world wide as the industry standard. Below are some of the items we design and manufacture for the lost foam process.
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