SCRATA association is the first company in Britain to apply lost foam casting process, and its process method is replica method. There are two options for this method:
The first method is called replicate FM method: it combines the advantages of gasification mold casting method and vacuum molding method. The mold is loaded into the sand box, then filled with sand, and the molding sand is compacted through mechanical vibration. The method of vacuumizing the cavity during pouring (the vacuum degree is 300 ~ 380mmhg) has great development space in the production of iron castings below 20t.
The second is called replicate CS method (shell molding): this method is widely used in castings with high quality requirements, such as the production of low-carbon steel castings and alloy parts sensitive to EPS decomposition products. This method is similar to investment casting. A ceramic coating layer with a thickness of 3.2 ~ 4.7MM is coated on the outer surface of high-density EPS pattern. After the coating is sintered and the pattern is gasified, it is placed in a special sand box, and then vibration modeling is carried out. The sand box is vacuumized during pouring (the vacuum degree is 300 ~ 380mmhg). This method is suitable for the production of high-quality precision steel castings. The dimensional accuracy of lost foam casting RA ≤ 12.5mm and wall thickness 2.5 ~ 100mm can reach 0.25mm; The dimensional accuracy of lost foam castings with wall thickness less than 300mm is 0.75mm; the dimensional accuracy of lost foam castings with wall thickness less than 600mm is 1.5mm. The machining allowance of the above lost foam castings is 1.6 ~ 3.2mm.