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3 tips for extrusions vs. formed break metal

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One should expect better results in curving an extrusion vs. curving break metal, primarily because formed break metal can have dimensional inconsistencies.
Critical factors in determining the results of any material are the tightness of the radius and the shape’s size and its orientation.

Stretch Forming Machine

Then one must consider the alloy and temper (hardness). Sheet metal is often stocked in alloys and tempers that are difficult to curve with good results. Also, some stocked items are not heat-treatable. The best alloy/temper in sheet metal for curving is 3003-H14.

tips 1#: Size of shape considerations

Shapes of under a 10” circle size can be curved as a general rule. Always ask about larger sizes as press adjustments may be possible. With regard to length, we can best optimize pieces of 12’ or 24’.

Note: 12” are lost on each end in the curving process.

tips 2#: Temper/Alloy considerations

The end use of the curved metal is critical here. If it is load-bearing or structural application, we MUST receive the aluminum in a soft temper (designated T1 or T4). We will temper it to a T5 or T6 as required after curving. If it is NOT a structural application, we can receive tempered metal and anneal it (soften using high heat).

Caution: once aluminum is tempered and then annealed, it cannot cost-effectively be re-tempered.

tips 3#: Pre-finished or thermally-broken aluminum

There is always less risk to finish after curving. If annealing is required, you MUST finish after curving except in cases of:

  1. Some pre-anodized finishes
  2. If we receive the metal in a soft temper or
  3. If the shape is small and the radius needed is open to a curve it is hard.

Of course, if received in a soft temper (#2 above), it would not be able to age or temper the metal after curving as the heat would damage the paint or thermal material. For most applications, however, work hardening is adequate.
Keep in mind that curving pre-finished material will most likely void any warranty on the finish.

Send us the extrusion dimensions or a drawing and we will give you our estimate for a minimum radius and go over issues you might encounter.

Why would you need to curve metal using the stretch-forming process?

stretch forming machine
stretch forming machine

The job requires consistent dimensions throughout the curve without twisting, distortion, or waviness and/or has a tighter radius than achievable with other methods.

Why should you use Southern Stretch Forming for your curving needs?

  1. In-house annealing and tempering,
  2. Curving of aluminum as well as stainless steel, bronze, muntz, copper, etc.,
  3. Curving of spirals and serpentines,
  4. Finishing after curving available,