LOST FOAM CASTING PROCESS
Providing Unparalleled Custom Metal Casting Production
And Serving All The World Lost Foam Investment Casting
NBSJ offers lost foam casting production services and custom products manufactured through this casting process.
The lost foam casting process is similar to investment casting, except foam is used for the pattern instead of wax. This process simplifies the investment casting process by removing the need to melt the wax out of the mold because polymer foams have a lower boiling point.
NBSJ has developed the lost foam casting process for more than ten years. We can improve metal casting products with more accurate dimensions and smoother surfaces by applying lost foam casting instead of the sand casting process. As a metal casting service supplier, we equipped the foundry with advanced testing instruments such as molten metal analyzers, spectrometers, and metallographic microscopes to guarantee the casting metal’s grade and mechanical properties.
And we usually apply the lost foam casting process to manufacture larger products. The casting materials include cast irons, carbon steels, and some alloyed steels. Meanwhile, we have our own CNC machining workshop, where we can make the after-casting machining of the casting blanks to meet the customers’ one-stop requirements.
If you have a metal part that needs to be customized, either for prototype or mass production, contact us now and immediately enjoy our services.
What is a lost foam casting process?
Lost foam casting is a new modern casting method. Firstly we need to make foam patterns(made from polystyrene) and bond them together to form pattern clusters to prepare for the following casting process. And the foam clusters need to be coated with refractory paint and wait to be dried. After that, we will bury them in dry quartz sand and vibrate them to shape. While pouring, the molten metal vaporizes the foam, fills up the entire cavity under negative pressure, and forms the casting workpiece after solidification and cooling.
The molten metals applied for the lost foam casting process include cast iron, carbon steel, and some alloyed steels. Large-sized parts up to several tons apply to this process too.
There are several procedures involved in the lost foam casting process.
1. Pattern making – Design and create the polystyrene foam patterns via hand cutting or machining processes. If there is a large volume production, we usually make a metal die to inject the pre-expanded polystyrene beads to form a pattern. And if necessary, we can also bond the single foam patterns to create a foam cluster via hot gluing.
illustration – foam patterns
2. Foam coating – The foam cluster will get coated with the refractory paints via dipping, brushing, or spraying. The coating materials need to have good performance, and mostly it needs to be strong enough to prevent sand erosion and deformation while pouring. Meanwhile, the permeability is another crucial point, and it allows the gas created by the vaporized foam pattern to escape through the coating and into the sand. And these coated foam clusters need to be dry before being placed into the casting flask.
illustration – foam coating
illustration – drying coated foam patterns
3. Pouring – Place the foam clusters into the casting flasks and fille up the flasks with dry and unbonded sand. And once the sand is compacted, the mold is ready to be poured. Melt the desired metal and pour it into the mold through the gates left open outside.
illustration – lost foam cast pouring
4. Castings divesting – After the castings get cooled, we need to get the castings rid of the sand, and sand-blasting is always necessary to make the surface clean and smooth;
illustration – sand divesting
illustration – casting sand blasting
Advantages of the lost foam casting process include
High accuracy of the dimensions
Better surface roughness than sand casting
Easy sand divesting because of the dry and unbonded sand
None mold parting lines
High production rate
Low labor cost
Suitable for products with complex shapes and structures