Blow mold materials must have high thermal conductivity and sufficient cutting edge strength. Aluminium 70/75 is currently an advanced alloy used to make most molds. Due to the good machinability of this metal, the cavity is usually machine cut. Po copper alloy mold also has high heat transfer and good corrosion resistance. However, its cost is high and its price is high, and its specific gravity is three times that of aluminum, which may cause severe wear on the molding machine. Po steel alloy molds are easy to repair by welding or setting.
The thermal conductivity of the cast aluminum mold is worse than that of the cut aluminum mold. The cut opening of the mold cavity usually needs to be broken with copper alloy or stainless steel, because the strength and hardness of cast aluminum cannot meet the requirements of the cutting edge of the cut opening.
Exhaust of the blow mold When the part is blow-molded, the mold must be vented in order to quickly escape the gas. The most common and economical method of venting is surface venting. Deep blasting or texturing the cavity can also help with venting. Another important reason to vent (for those parts where plastic must be blown into tight, narrow spaces) is to show detail.
