The hollow sprue and suitable vacuum pressure is helpful to decreasing the pinhole,but,when the vacuity is too high,the liquid aluminum would become turbulence causing pinholes increased.

• 充型过程中施加一定的真空度有利于减少针孔，但真空度太高则会促使铝液产生紊流，反而增加铸铝件的针孔，降低其密度。