The shell molding process offers better surface finish, better dimensional tolerances, and higher throughput due to reduced cycle times.
A heated (200 Deg C / 392 Deg F) metal pattern is covered with a mixture of sand and thermoset plastic. This causes a skin of about 3.5 mm (0.125 in) of sand/plastic mixture to adhere to the pattern. This skin is removed from the pattern to form the “shell mold” The two halves of the shell mold are secured together and the metal is poured in the shell to form the part. Once the metal solidifies, the shell is broken.
This process can produce complex parts with good surface finish 1.25 mm to 3.75 mm rms, and dimensional tolerance of 0.5 %. Size limits of 30 g to 12 kg (1 oz to 25 lb). Minimum thicknesses can be as low as 1.5 mm (0.062 in) to 6.25 mm (0.25 in), depending on the material. A good surface finish and good size tolerance reduce the need for machining.
A fairly high capital investment is required, but high production rates can be achieved. The process overall is quite cost effective due to reduced machining and cleanup costs.
The materials that can be used with this process are cast irons, and aluminum and copper alloys. Typical parts made with this process are connecting rods, gear housings, lever arms etc.
Sinotech can ensure excellent shell mold castings from China, Taiwan and Korea and is very price competitive. Sinotech has audited, qualified and worked with QS-9000 and ISO certified shell mold casting factories in China, Taiwan and Korea for over 12 years. Sinotech is dedicated to managing your project on-site and delivering parts to you at lower prices but the same quality, service and terms as a domestic supplier.
