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Pittsburgh and Schnappfalz connection

Flanging is a joining technique used in sheet metal processing. It belongs to the group joining by forming .


The gilded tin roof of the Dome of the Rock in Jerusalem has been made watertight by flanging
Flaring with the RAS 21.20 flanging machine
Section through a faulty (left) and a correct flanging (right)
Flaring tool for brake lines and thin tubes

Flanging is the process of bending the edge of sheet metal with a flanging machine or by hand. A stiffening of the bent edge is achieved or a connection is created from several components.

With manual flanging, a distinction is made according to the type of forming:

  • If the sheet is compressed during forming, it is called flanging. You use a flanging iron , a tool that resembles an upright, wide, crooked chisel , but has no cutting edge, but a rounded edge.
  • If the sheet metal is stretched, the process is called tailoring and is carried out with a tail hammer .

Flanging machines effect both types of forming with the same tool technology.

Pipe connection

In refrigeration technology, for hydraulic and brake lines, for example, copper, steel or aluminum pipes are initially provided with a union nut . Then the end of the pipe is widened in a funnel shape with a suitable flanging iron. The tube, which is now provided with a flanged flange, is screwed through the union nut without any further sealant. Such connections can be detached, but are often not screwed in a second time for safety reasons.

Car tuning

To mount wide tires and corresponding rims, it is sometimes necessary to fold or widen the fender edges even on vehicles that are not lowered. The hemming and flanging tool solves these problems by simply and evenly turning the wheel arch edges.

Air duct connection

Flaring is a common process used to make air ducts . The flanging machine sets up a rim on a circular disk cut out of sheet metal on the inner and outer radius. This so-called standing seam , when inserted into the so-called Pittsburgh seam, creates an airtight seam connection on circular arc segments of a rectangular air duct.

See also