Low pressure die casting production defects causes and elimination
Low pressure die casting production castings relatively easy to produce some casting defects are many reasons, and casting equipment, molds, process and specific operating, in order to obtain a high-quality magnesium alloy castings, quality issues must be generated to make the right judgment, to find out the real reasons and propose the corresponding practical effective improvement measures to improve the quality of the casting. In this paper, the magnesium alloy low pressure casting process, according to the simulation analysis, predicted porosity and shrinkage defects that may arise.
Porosity: the reason for the formation of pores general, there are two, one is involved in the formation of gas within the surface shiny and smooth when filling, regular shape empty. Another alloy melting incorrect or inadequate refining, the gas is dissolved in the alloy. Die casting, rapid solidification, precipitation of the gas dissolved in the metal internal too late, so that the gas within the metal and the formation of voids left in the casting.
During filling the pores of spokes central part of the first case described above, the improvement measures are: to reduce the speed of the ingate; changing the geometric structure of the spokes.
Shrinkage: the casting during solidification, metal compensator dark, rough surface, irregularly shaped cavity. Hub formed during solidification shrinkage, mainly due to the wheel center location and design of the mold caused by the irrational. Improvement measures: to improve wheel center parts of the the fully axisymmetric structure; improve the cooling system of the