An auto stacker or stacking machine has been built with two main parts: Supporting part and Transportation part. The Supporting part are composed of many arms which is working under pneumatic power to close up and open down so that the roll formed products or the cut metal sheets can drop down to the transportation part which is made of steel frames with many tubes mounted and the part is working with motor power so that the stacked sheets can be moved out and transported to warehouse with a forklift.

Limit or proximity switches are used to control an auto stacker or auto stacking machine. Simply speaking, when the roll formed products or cut metal sheets are pushed to the stacking machine and touch the upper switch, the arms will open down and the sheets will drop down accordingly; when the arms open down to the lower switch, they will close up.

There are usually two lengths for auto stackers, 6 meters and 12 meters for stacking roll formed products or cut metal sheet with different lengths. With an auto stacker, only one operator is enough to run a roll forming line, while two or three employee at least are needed for a roll forming machine with traditional no-power runout tables.