Case formers, or case erectors, are the first step in the over packing process for most products.

Case erectors differ from cartoners in that they work primarily with corrugated boxes which have four sides and four flaps each for the top and bottom openings. The case erector takes the knocked down (KD) blank, pulls it open, folds the bottom flaps and seals them with glue (hot or cold) or with tape (contact adhesive or wet adhesive). Once the bottom is sealed, the case is rigid and can then be moved to the station for loading the product.

The knocked down case blanks (KD) are usually loaded by hand. Some equipment for automating this step is available, but is usually of custom design.