The lost foam molding machine and other lost foam equipment are first made into foam plastic models (craftsmanship, machinery) according to the EPC process, coated with special coatings, dried, placed in a special sand box, filled with dry sand, compacted by vibration, and cast under vacuum state. The model vaporizes and disappears, and the metal liquid replaces the model to replicate the same casting as the foam plastic model.
1. Obtain excellent castings, eliminate carbon defects, improve internal product quality, and ensure castings. The so-called carbon disadvantage refers to the various disadvantages caused by the objective existence of carbon in EPS, which are collectively referred to as the carbon disadvantage of lost foam equipment during the pouring and solidification process of molten metal. Carbon defects of EPC equipment include carbon increase, slag inclusion, wrinkling, uneven composition, poor mechanical function, coarse grain, hard and brittle appearance, and decline in welding and machining functions caused by carbon pyrolysis in foam, as well as porosity directly caused by carbon.
2. Unstable process ① Ensure a high initial negative pressure requirement for pouring (above 0.06MPa). Since the EPS foam in the mold burns off, the vacuum degree of the negative pressure field drops rapidly, which is easy to make the pouring fail. In order to ensure a vacuum level of 0.02 MPa (non collapsing negative pressure value) even after reducing it to a low value, it is necessary to ensure a high negative pressure value during the initial pouring process. However, if the negative pressure value during pouring is too high, the surface of the casting is prone to sand sticking and porosity After the EPS foam in the mold is burned off, during the pouring process, “three leakages” (sand leakage, air leakage, liquid metal leakage) are likely to occur at the joints between the pouring cup and the runner and the riser, resulting in box collapse, casting sand inclusion and other defects after the negative pressure value drops rapidly.
3. The manifestation of the box is particularly prominent, which is a problem encountered in the production practice of lost foam equipment technology, often leading to pouring failures, increasing the scrap rate of more lost foam machine casting manufacturers, and then not being better promoted and applied.