C Z Shape Purlin Forming Machine Full Automatic Change Size Type CZ channel changeable roll forming machine CAN produce two different type of shape purlin in one machine, C type purlin has good straightness and has good compression and bending resistance. Z type purlin can be installed in reverse lap, and the installation strength of the connection point will be increased. with it high productive speed, it can help client save labor cost and save more space. Specification No.