Metal Deformation Flashcards
Distinguish compound-die versus progressive-die operations and their relative merits
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Describe differences and relative merits between open-die forging and impression-die forging
o Open-die forging: A hammer strikes and deforms the work piece, it is the simplest forging operation, the dies do not enclose the work piece
o Impression die forging: The work piece takes the shape of the die cavity while being forged between two shaped dies
Distinguish various types of extrusion, in particular direct extrusion, indirect extrusion. Also distinguish extrusion from drawing (rod and wire).
o Direct extrusion (forward extrusion): A billet is placed in a chamber and forced through a die opening by a hydraulically driven ram.
o Indirect extrusion (backward extrusion): The die moves toward the un-extruded billet, no billet to container friction, therefore good for materials with very high friction (high-strength steels)
Describe the process of rolling, the types of shapes that can be produced by rolling.
o Sheet metal is fed into the rollers which gradually form the product as the metal progresses through the rollers. Good at forming long continuous shapes with constant cross sections such as gutters
- Name example parts that are well-suited to fabrication by sheet metal processes, and identify specific operations that would be useful in producing required geometric features in sheet metal parts.
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- Describe and distinguish a variety of sheet metal deformation operations, in particular: including press-brake bending, roll bending, stamping, drawing, roll forming, hydroforming, and spinning.
o Press-brake bending: Utilizes a press and simple fixtures to bend sheet metal or plate
o Roll bending: Plates and sheet material are bent using a set of rolls, which can be adjusted to accommodate a wide variety of curvatures.
o Drawing (and “deep” drawing): A punch forces a sheet metal blank into a die cavity, can produce shallow parts (drawing) and deep parts (deep drawing).
o Beading: Forming the edge of the sheet into a circular rolled edge; this improves stiffness, appearance, and eliminates exposed sharp edges.
o Hemming: Edge of the sheet is bent back over itself and flattened; this improves stiffness, appearance, and eliminates exposed sharp edges.
o Stamping: Includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining.
o Embossing: Shallow or moderate draws made with matching male and female dies, typically used to stiffen the sheet metal and for decorating, numbering, and lettering.
o Roll forming (contour-roll forming): Used for forming continuous lengths of sheet metal and large production runs. Set of rollers bends the metal in stages in a continuous process.
o Hydroforming: Fluid pressure is used to assist in drawing the material into the die; tube hydroforming uses a pressurized fluid (typically water) to form the metal tubing into a die.
o Spinning: Forming an asymmetrical part over a mandrel by use of various tools and rollers
- Compare relative merits and limitations of various metal deformation processes in terms of dimensional control, shape complexity, material variety, production rate, and cost.
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