Analysis of defects of common lost mold casting process

EPC process is different  traditional casting process  some casting defects are  seen in other molding process.The casting defects should be analyzed according to the characteristics of EPC technology,  the correct countermeasures should be taken.

1. Cast mold damage

Mold damage is a common defect when unbonded sand is used.(1) The upper part of the casting mold collapses.(2) local cavity in the cavity causes mold damage.(3) Mold damage caused by improper setting of the gating system.

2. Insufficient casting

The low fluidity of molten metal in the alloy with low casting temperature is unimaginable according to the experience of other casting processes.Therefore, insufficient pouring  cold separation are common defects.In the production of thin-walled castings, it is also easy to produce insufficient casting defects.Appropriately raising the pouring temperature is the first measure that should be considered.

3. Adhering sand

Sand is one of the common casting defects in EPC process.(1) high pouring temperature.(2) Insufficient compactness of sand filling.

4. Surface carburization of steel castings

Carburization on the surface of steel castings, especially stainless steel  low carbon steel castings, is a problem.The depth of carburizing layer is generally 0. 5 ~ 2. 5mm, depending on the original content of molten steel  the thickness of casting wall.

5. Porosity

(1) the air hole caused by being involved in the mould.(2) the air permeability of the paint caused by poor pores.(3) The pores caused by insufficient drying of the foaming mold.(4) the coating layer is  dry caused by pores.(5) pores caused by adhesives.

6. Deformation of foaming die causes casting deformation

(1) Foaming mold should be fully dried after forming.(2) when coating  drying coating, avoid deformation of foaming mold.(3) when sand filling molding, the foaming mold is the most easy to deform,  should be carefully operated, especially  all the molding sand can be put into the sand box at one time.

7. Spray metal liquid at sprue

When the decompression degree in the sand box is too high  the molten metal filling is too fast, the molten metal is easy to be involved in the bulk molds that have contracted in volume but have  been fully pyrolysis.The continuous pyrolysis  gasification of the mould will result in the ejection of the metal liquid  the sprue.