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Superplastic Forming Process of Sheet Metal

Superplastic forming (SPF)

The superplastic forming process having the sheet metal to be formed and it placed on SPF die (or) mold, the die have simple or complex shape geometry, and then representative of final part to be formed together. During the super plastic forming process the elevated temperature will occur the sheet metal stress is very low.

When the forming process the sheet metal and tooling are heated together and then high pressure of gas is applied. That case, the sheet metals are plastically deformed into desire shape of die cavity.

Which superplastic process the multiple sheets such as aluminium, titanium, stainless steel and more other matel to be joined into a flat sheet preform by using automated laser welding process.

The selected areas only weld to be done. Then other areas are separated stop off. After sheet metal welded for desired pattern, then the sheet is placed on the die and clamps by using clamping device the preformed heat of superplastic forming in die form.

The temperature range of titanium alloy is 900⁰ and alluminium alloy is 500⁰c. The pressurized inert gas (up to 2 Mpa) is introduced in between unweld area and sheet metal. The processing time nearly 4 hours approximately. That time interval the formed into die cavity achieved. When the process the material are elongated exceeding in 200%.

The preform of sheet metal is elongated into integral stiffing member between outer sheets of metal. The stiffness of metal core is determined by pattern of laser welding sinusoidal, truss core and other internal stiffening geometric are produced a single form step by using automatic weld pattern. The pressure of forming and single step processing are more significantly reduce tooling cost and that compare to conventional method.

Advantage of superplastic forming:

Lower strength require the tooling
The most complex can be formed
No residual stress induced during the parts of formed
Tooling cost low
High rate of forming

Materials:

The superplastic forming process suitable for some certain material only. That having very fine grain structure of less than 10 to 15 um size.
The below material of SFP:
Iron based high carbon alloy
Incol 100
7475- T6 aluminium alloy
Incoloy 718
T1- 6A1- 4v titanium alloy

SPF can be formed complex shape with stiffening rims and other structural features. And also thermal and mechanical processing lead to increase in super plasticity performance.

The superplastic forming evaluates the new material and best optimize form cycle. Accurately mechanical test methods to help develop material constitutive relationship and processing models.