Forming techniques Superplasticity

1 forming techniques

1.1 cavity forming
1.2 bubble forming
1.3 diaphragm forming

forming techniques

there 3 forming techniques in use exploit these advantages. method chosen depends upon design , performance criteria such size, shape, , alloy characteristics.

cavity forming

a graphite-coated blank put heated hydraulic press. air pressure used force sheet close contact mould. @ beginning, blank brought contact die cavity, hindering forming process blank/die interface friction. thus, contact areas divide single bulge number of bulges, undergoing free bulging process. procedure allows production of parts relatively exact outer contours. forming process suitable manufacturing of parts smooth, convex surfaces.

bubble forming

a graphite coated blank clamped on tray containing heated male mould. air pressure forces metal close contact mould. difference between , female forming process mould is, stated, male , metal forced on protruding form. female forming mould female , metal forced cavity. tooling consists of 2 pressure chambers , counter punch, linearly displaceable. similar cavity forming technology, @ process beginning, firmly clamped blank bulged gas pressure.

the second phase of process involves material being formed on punch surface applying pressure against previous forming direction. due better material use, caused process conditions, blanks smaller initial thickness compared cavity forming can used. thus, bubble forming technology particularly suitable parts high forming depths.

diaphragm forming

a graphite coated blank placed heated press. air pressure used force metal bubble shape before male mold pushed underside of bubble make initial impression. air pressure used other direction final form metal around male mould. process has long cycle times because superplastic strain rates low. product suffers poor creep performance due small grain sizes , there can cavitation porosity in alloys. surface texture however. dedicated tooling, dies , machines costly. main advantage of process can used produce large complex components in 1 operation. can useful keeping mass down , avoiding need assembly work, particular advantage aerospace products. example, diaphragm-forming method (dfm) can used reduce tensile flow stress generated in specific alloy matrix composite during deformation.