Hemming and seaming

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hemming process
A closed hem
A seam

Hemming and seaming are two similar metalworking processes in which a sheet metal edge is rolled over onto itself. Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials.[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, and in the automotive industry.

Process[edit]

The process for both hemming and seaming are the same, except that the tonnage requirement is greater for seaming. The process starts by bending the edge to an acute angle. A flattening die is then used to flatten the hem.[1]

Types[edit]

There are two types of hemmed edges: closed hems and open hems. Closed hems are completely flush while open hems have an air pocket in the bend. The major difference is that the tonnage required for a closed hem is much greater than that for an open hem.[2]

Tons per meter requirement for hemming cold-rolled steel and stainless steel[2]
Material thickness [mm] Open hem Closed hem
0.6 9 23
0.8 12 32
1.0 15 40
1.2 17 50
1.6 24 63
2.0 30 80
2.6 55 90
3.2 70 100
4.5 105 200

See also[edit]

References[edit]

  1. ^ a b c Benson 1997, p. 137.
  2. ^ a b Benson 1997, p. 138.

Bibliography[edit]

Further reading[edit]