Gas block, cast parts under the surface lubrication, but the shape is irregular, it is difficult to set the overflow system, gas accumulation; When the molten metal to move, turbulence is strong, gas are closed. 3 it is plastic cavity with residue, dosage of coating or coating method is undeserved, cause local coating deposition. Solution to the die casting crack: improving the structure of the die casting, increase the transition fillet, reducing the wall thickness difference. Enhance pouring temperature, mold temperature and improve the flow of metal stamping parts alloy liquid state. Shorten the time of die casting mould, especially for high brittleness of the die casting alloys, such as high content of zinc magnesium alloy. Control of impurities, iron and silicon content in the alloy. Adjust the position of the introduced element to strengthen thrust plate guide a guiding role, make the introduction of force balance. Reinforced core strength, stiffness and smoothness, increase the core of the draft and smoothness.
The surface of the die casting processing anodic oxidation treatment: extrusion profile surface corrosion resistance is not strong, need to be carried out in accordance with the anodic oxidation surface treatment, improve the profile of titanium machining parts the corrosion resistance, abrasion resistance and appearance. Principle of electrophoresis coating: principle of electrophoresis coating material surface gloss, resistance to acid rain corrosion of concrete and cement mortar.
Powder electrostatic powder spraying, powder electrostatic powder coating profiles is the feature of corrosion resistance, better than the air oxidation coloring material. Shell die casting processing technology, the classification of low pressure (pressure is less than 20 mpa), medium pressure (pressure is less than 300 mpa) and pressure (pressure is greater than 3000 mpa) of three methods for casting. Vacuum casting, such as vacuum suction casting. Atmospheric pressure casting, usually used for metal mold casting and sand casting process. Pressurized solidification, centrifugal casting, high pressure casting solidification (such as liquid die forging).
Why can't die casting shell oxidation? Usually high silicon content alloy castings and casting. Even use special ash agent, anodic oxidation film will show puce, can not be completely transparent colorless air oxidation film. Then, silicon water content deep draw stamping increases, the oxide film color from light gray to dark gray to a film. As a result, the alloy casting is not suitable for the traditional oxidation treatment. The causes of deficiency of shell casting foundry Part under filling condition is poor, casting metal condensation is irregular; When pressure is insufficient or inadequate, active metal solidification front too early, there will be a marginal, deep concave, thin wall (or even better than the average wall thickness thin), owe cast in areas such as the cylinder hole wall. Mold temperature is too low; Alloy pouring temperature is too low; Gate location is not good, resulting in large in the resistance movement.