Chapter 18 Flashcards
Define: Net Shape
Processes that achieve final product geometry with little or no subsequent machining.
Define: Flat Rolling
A process using two opposing rolls to exert compressive forces on a slab to reduce the thickness of a rectangular cross section.
Define: Bloom vs. Billet vs. Slab
Bloom: Square cross section (150 x 150 +)
Billet: Square cross section (40 x 40)
Slab: rolled from an ingot or bloom; rectangular cross section with small thickness
Define: Draft
The amount eh thickness is reduced; d = T init - T final
Define: Reduction
Fractional representation of draft in which:
r= d / T init
Define: Spreading
When the width of the working material increases because the thickness is reduced. (volume in = volume out)
Define: Two-High vs Four-High
Two High: Basic rolling design with two opposing rolls
Four High: The use of two smaller diameter rolls to contact the work and two backing rolls behind them.
Define: Reversing
Allows the direction of the roll rotation to be reversed, so that the work can be passed through in either direction.
Define: Ring Rolling
Deformation process in which a thick-walled ring of small diameter is rolled into a thin-walled ring of larger diameter
Define: Roll Piercing
Specialized hot working process for making seamless thick-walled tubes. It utilizes two opposing rolls, and hence it is grouped with the rolling process. Uses a mandrel to create the tube
Define: Open-Die vs Closed-Die (Impression) vs Flashless vs Precision Forging
Open Die: Work is compressed between two flat (or almost flat) dies, thus allowing the metal to flow without constraint in a lateral direction relative to the die surfaces.
Closed Die: The die surfaces contain a shape or impression that is imparted to the work during compression
Flashless: The work is completely constrained within the die and no excess flash is produced.
Precision Forging: Another name for flashless forging
Define: Fullering
Forging operation performed to reduce the cross section and redistribute the metal in a work part in preparation for subsequent shape forming
Define: Edging
Similar to fullering, except that the dies have concave surfaces
Define: Cogging
A sequence of forging compressions along the length of a workpiece to reduce cross section and increase length
Define: Coining
Special application of closed-die forging in which fine details in the die are impressed into the top and bottom surfaces of the work part; good surface finish and dimensional accuracy
Define: Upsetting
(or upset forging) is a deformation operation in which a cylindrical work part is increased in diameter and reduced in length
Define: Heading
Same as upsetting but more specifically used to form the heads on nails, bolts, and similar hardware product.
Define: Swaging
Forging process used to reduce the diameter of a tube or solid rod. Metal rod is slammed through a rotating die with a tapered midsection to produce the necessary shape.
Define: Radial Forging
Similar to Swaging in that diameter reduction occurs, however, the rod spins radially during forging and not the die itself.
Define: Roll Forging
Deformation process used to reduce the cross section of a cylindrical workpiece by passing it through a set of opposing rolls that have grooves matching the desired shape of the final part.
Define: Orbital Forging
Deformation occurs by means of a cone shaped upper die that is simultaneously rolled and pressed into the work part. This upper die is revolving to reduce press load and therefore accomplish the deformation
Define: Hubbing
Deformation process in which a hardened steel form is pressed into a soft steel block. The hardened steel “hub” is machined to the geometry of the part to be molded and acts more as a ram to they system.
Define: Direct (forward) vs indirect (backward) extrusion
Direct: a metal billet is loaded into a container and a ram compresses the material, forcing it to flow throught one or more openings in a die at the opposite end of the container.
Indirect: The die is mounted to ther ram rather than at the opposite end of the container; used to create hollow cross sections
Define: Extrusion Ratio
Original X-Sectional area / Final x-sectional Area
