Hemming and seaming

Hemming and seaming are two similar metalworking processes in which a sheet metal edge is rolled over onto itself.

[1] Hems are commonly used to reinforce an edge, hide burrs and rough edges, and improve appearance.

[1] Seams are commonly used in the food industry on canned goods, on amusement park cars, in metal roofing (with a roof seamer), and in the automotive industry.

The process for both hemming and seaming are the same, except that the tonnage (amount of force exerted) requirement is greater for seaming.

The process starts by bending the edge to an acute angle.