Metalforming Processes
Conventional Processes
Sheet forming processes
ROLLING
other terms strip, flat, plate
definition The reduction of the cross-sectional area of metal stock, or the general shaping of metal products, through the use of rotating rolls.
STAMPING
other terms
definition The general term used to denote all sheet metal pressworking.
DRAWING
other terms deep, ironing, (not to be confused with rod, wire or tube drawing – see bulk processes)
definition A term used for a variety of forming operations, such as deep drawing and/or ironing a sheet metal blank. The usual drawing process with regard to sheet metal working in a press is a method for producing a cuplike form from a sheet metal disk by holding it firmly between blankholding surfaces to prevent the formation of wrinkles while the punch travel produces the required shape.
HYDROFORMING
other terms fluid forming
definition In Hydroforming, the pressure over a rubber membrane or directly to the sheet is controlled throughout the forming cycle, with maximum pressures of up to 100 MPa (15,000 psi). This procedure allows close control of the part during forming to prevent wrinkling or tearing. Deeper draws are obtained than in conventional deep drawing because the pressure around the membrane or sheet forces the cup against the punch. The friction at the punch-cup interface reduces the longitudinal tensile stresses in the cup and thus delays fracture. The control of frictional conditions in sheet forming operations can be a critical factor in making parts successfully. Selection of proper lubricants and application methods is important. Recent developments have introduced multi pad CNC controlled pressure draw rings to provide continuously variable friction factors around the sheet surface.
When selected properly, rubber forming processes have the advantages of low tooling cost, flexibility and ease of operation, low die wear, no damage to the surface of the sheet, and capability to form complex shapes. Parts can also be formed with laminated sheets of various nonmetallic materials or coatings.
SUPERPLASTIC FORMING
other terms
definition High temperature creep based hydroforming operation. Normally used on high added value difficult to form materials e.g. aerospace applications. Fine grain size, temperature and strain rate control essential for success.
