By using system analysis method,the choke blow hole defect of the rear wheel boss was sy stematically analyzed and proved,and then adopted proper method to control and improve the production pro cess.

The defects of blowhole shrinkage and boiling often occurr in the production of cast steel bracket,and the process yield is low,the core cost is high.

It was considered that because of the poor exhaust of cores or the molten iron choked the venting channel of the cores, the gas from the cores during pouring made the melt boiling in mold, which resulted in blowholes defect mentioned above.

Effect of Topical Anesthesia to Tunica Mucosa Tracheae on Hemodynamics Fluctuation and Bucking Incidence;