Indian Foundry Congress & IFEX 2010
58th Indian Foundry Congress & IFEX 2010 Date of Fair: 5th - 7th February 2010 Venue: Gujarat University Exhibition Hall, Ahmedabad, India Stall No. : N10
Lost Foam Process provides closer tolerances, better surface finish and no mismatch compared to conventional Green Sand Process. It is a coreless process hence total elimination of fins and flashes on the casting is achieved. Products which have been designed keeping in mind the Lost Foam Process have dramatically reduced its machining cost as well as achieved lower casting weight, hence lower cost of product.
Lost Foam Process is most suitable for intricate cored castings in high volume in any weight range from 250 gm to 50 kg / Pc.
Lost Foam Process
Lost Foam Process is similar to Lost Wax (Investment casting) process.
First a foam pattern is molded using Expandable Polystyrene (EPS) or co-polymer which is an exact replica of the desired casting. Runners and risers are attached by glue to the foam pattern and a cluster is made of one or more number of foams. The cluster is then coated with a permeable refractory slurry coating in a homogenous bath by dipping.
The dry coated cluster is invested in a flask by sand and vibrated to compact the sand around the cluster in the flask. Molten metal is poured through the pouring cup into the foam cluster. The molten metal replaces the foam which gets evaporated. On solidification of the metal, the sand is drained off the flask and the tree is removed. The castings are knocked out from the metal cluster, fettled and finished before it is shipped out.
Advantages:
Lost Foam Process has following advantages over conventional Green Sand Process.
Closer tolerances on dimensions.
Permits lesser machining allowance and subsequent reduction in the weight of castings.
No mismatch. Suitable for direct CNC / SPM operations by eliminating pre-machining.
Merger of many simple casting components into a complex and intricate shaped single casting to save machining cost and reduction in casting weight.
It is a Coreless process hence total elimination of Fins and Flashes on the casting.
Better surface finish. No sand inclusions and hence increased cutting tool life.
Excellent process for intricate and complex shaped and high volume casting requirement.
