Epc casting process is generally a new casting method in which the surface of the processed plastic foam pattern is coated with a certain thickness of fire-resistant coating,and then put into a sand box.Self-hardening resin sand is adopted to make solid shape outside,and pouring is done under negative pressure to vaporize the pattern,and liquid metal occupies the position of the pattern,and the casting is formed after solidification and cooling.

　　Although disappearing mould technology is a relatively advanced environmental protection public welfare,but there will be many problems,mechanical sand is one of them.

　　Mechanical sand performance

　　Mechanical sand is also known as"iron-clad sand",which means that molten iron penetrates into the pores between the sand grains and mechanically sticks the sand grains to the surface of the casting after solidification.

　　1,between the coating and molding sand parts of the mechanical sand,sand exposed to the surface,most of the slope.

　　2.A uniform layer of"iron-clad sand"is adhered to the surface of the casting.

　　The cause of mechanical sticking sand

　　There are two reasons for***defects:

　　1.In order to ensure the uniformity of the casting wall thickness,the sample designer designs a structure that is not easy to grind sand or cannot grind sand,and even presents a very narrow hole cavity in the pattern.

　　2,the negligence of the model worker.

　　The causes of the second type of defect are also two aspects:

　　1,the composition of the composition,the type of coating aggregate,fire resistance and mutual ratio,the coating layer thickness requirements and anti-sand effect is very influential;

　　2,layer thickness,coating thickness is too large,labor cost materials;Coating thickness is too small,high temperature liquid iron will penetrate through the coating sand particle gap,resulting in sticky sand.

　　Mechanical sand prevention

　　The main preventive measures are as follows:

　　(1)strictly review the pattern structure casting engineers in the pattern structure review,must carefully analyze whether the pattern structure is reasonable,for the impact of paint coating and prevent the unreasonable structure of sand compactor to be completely eliminated,in order to facilitate workers to work.

　　(2)to strengthen the monitoring of molding ground-up sand quality with full-time staff to manage the quality of the process,and the implementation of the whole process of ground-up sand quality tracking,supervision and inspection.

　　(3)strict coating preparation and coating quality,especially on the coating layer thickness monitoring,because of material,because of parts,because of time to carry out strict and flexible operations,to ensure that the coating to meet technological requirements.

　　(4)to strengthen the education of quality awareness,timely analyze and summarize the causes of the above-mentioned sand sticking defects of castings,and call relevant responsible persons to conduct on-site analysis of the defects.

　　(5)the incentive mechanism shall be adopted to quantify the severity and quantity of defects,and the relevant responsible person shall be given certain economic penalties.