brake drum 3600A/AX is the selling largest quantity in USA and Canada market along.
It's producing and casting works carfts also three different periods.
First period:raw material grey iron and generally casting works ,dynamic balance testing ways is cutting more weihgt or drill holes.
second period: use the Coated sand casting works,this made the 3600AX drums surface look like fine and exquisite
than the first period ,look like a crafts.
Third period: use alloy metal casting works producing for 3600AX brake drum;
carbon steel and grey iron alloy together keep the drum more strength and tensile than last two periods.