Gas porosity | Round and oval shape with smooth surface | Gas trapped during die casting process and gas generated by the decomposition of mold release agent | Equipping vacuum system, reasonable selection of process parameters and coating, and control of the amount of spraying |
Adhesion | Strip-shaped scratches along the mold-opening direction on the casting surface | Damaged or rough mold surface, high casting temperature or mold temperature, and bad release agent effect | Repair the damaged part of the mold surface, adjust the balance of the ejector rods, use the release agent with good release effect, and adjust the pouring and mold temperatures |
Cold shut | Irregular sunken linear lines on the casting surface | Poor fluidity of the alloy melt, low filling rate, low pouring temperature, and low mold temperature | Increase the pouring temperature, shorten the filling time, enhance the fluidity of the liquid metal, and improve the injection rate |
Defect band | A band of pores with solute segregation, distributed near the casting surface and some also in the core area | The shear force in the solid-liquid two-phase region causes the fragmentation, remelting, and coalescence of externally solidified crystals. It is difficult for liquid metal to fill at late solidification, resulting in a large number of pores | Increase the shear force, by increasing the injection rate and adjusting the vacuum time, to break externally solidified crystals |
Undercasting | Insufficient filling parts or incomplete casting contour | Poor fluidity, low pouring temperature, low mold temperature, too much involved gas, and poor operation | Optimize the alloy composition and improve pouring and mold temperatures |
Flow mark | Clearly visible, non-directional stripes that differ in color from the metal matrix | Low mold temperature, splashing due to too small cross-section area and inappropriate position of the inner gate, insufficient pressure on the metal, and too much coating | Raise the mold temperature, adjust the cross-sectional area and position of the inner gate, adjust the injection rate and pressure, and use appropriate amount of coating |
Deformation | Overall or partial deformation of the casting | Poor structural design, insufficient casting rigidity due to premature mold opening, uneven force during ejection caused by unreasonable setting of ejector rods | Improve casting structure, adjust mold opening time, reasonably set the number and position of ejector rods, and eliminate mold pulling problem |
Burr | Metal flakes appear on the edge of the parting surface | High injection rate, insufficient locking force, high pouring temperature, and worn and deformed hinge of die casting machine | Check the locking force, correct the mold, clean the cavity and parting surface, and reduce poring temperature and the injection rate |
| Slag inclusion | Irregular impurities on the casting surface and inside the casting | Unclean furnace materials, insufficient alloy purification, unclean casting mold, and slag and oxides brought into melt | Ensure the cleanliness of furnace materials, refine melt, and promptly clean the mold |
Crack | Network-like protrusions or indentations resembling hairs on the casting surface | Cracks on the surface of the mold cavity, high pouring temperature, rough surface of the mold cavity | Select high-quality mold materials, avoid too high pouring temperature, and sufficient and uniform mold preheating |
Drawing die | Difficult to smoothly demold | Insufficient mold surface roughness, carbon deposits and oxidation on the mold surface, improper or insufficient use of lubricants, unreasonable design of mold structure | Spray special coatings, perform surface treatment on the mold surface, select appropriate lubricants, and minimize mold deformation and wear |