Chapter 18

Question 1

Define: Net Shape

Answer 1

Processes that achieve final product geometry with little or no subsequent machining.

Question 2

Define: Flat Rolling

Answer 2

A process using two opposing rolls to exert compressive forces on a slab to reduce the thickness of a rectangular cross section.

Question 3

Define: Bloom vs. Billet vs. Slab

Answer 3

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

Question 4

Define: Draft

Answer 4

The amount eh thickness is reduced; d = T init - T final

Question 5

Define: Reduction

Answer 5

Fractional representation of draft in which:

r= d / T init

Question 6

Define: Spreading

Answer 6

When the width of the working material increases because the thickness is reduced. (volume in = volume out)

Question 7

Define: Two-High vs Four-High

Answer 7

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.

Question 8

Define: Reversing

Answer 8

Allows the direction of the roll rotation to be reversed, so that the work can be passed through in either direction.

Question 9

Define: Ring Rolling

Answer 9

Deformation process in which a thick-walled ring of small diameter is rolled into a thin-walled ring of larger diameter

Question 10

Define: Roll Piercing

Answer 10

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

Question 11

Define: Open-Die vs Closed-Die (Impression) vs Flashless vs Precision Forging

Answer 11

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

Question 12

Define: Fullering

Answer 12

Forging operation performed to reduce the cross section and redistribute the metal in a work part in preparation for subsequent shape forming

Question 13

Define: Edging

Answer 13

Similar to fullering, except that the dies have concave surfaces

Question 14

Define: Cogging

Answer 14

A sequence of forging compressions along the length of a workpiece to reduce cross section and increase length

Question 15

Define: Coining

Answer 15

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

Question 16

Define: Upsetting

Answer 16

(or upset forging) is a deformation operation in which a cylindrical work part is increased in diameter and reduced in length

Question 17

Define: Heading

Answer 17

Same as upsetting but more specifically used to form the heads on nails, bolts, and similar hardware product.

Question 18

Define: Swaging

Answer 18

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.

Question 19

Define: Radial Forging

Answer 19

Similar to Swaging in that diameter reduction occurs, however, the rod spins radially during forging and not the die itself.

Question 20

Define: Roll Forging

Answer 20

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.

Question 21

Define: Orbital Forging

Answer 21

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

Question 22

Define: Hubbing

Answer 22

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.

Question 23

Define: Direct (forward) vs indirect (backward) extrusion

Answer 23

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

Question 24

Define: Extrusion Ratio

Answer 24

Original X-Sectional area / Final x-sectional Area

Question 25

Define: Shape Factor

Answer 25

Ratio of the pressure required to extrude a cross section of a given shape relative to the extrusion pressure for a round cross section of the same area.

Question 26

Define: Impact Extrusion

Answer 26

The punch impacts the work part rather than simply applying pressure to it. Used for higher speeds and with shorter strokes than conventional extrusion.

Question 27

Define: Hydrostatic Extrusion

Answer 27

To reduce firction allong billet-container interface, the use of fluid inside the extrusion container and pressurizing the fluid by the forward motion of the ram

Question 28

Define: Wire/Bar Drawing

Answer 28

Used to distinguish the drawing process from sheet metal. Bar drawing refers to large diameter bar and rod inputs, while wire drawing applies to small diameter stock inputs.

Question 29

Define: Capstan

Answer 29

Each accumulation drum between the dies that are inside continuous drawing machines. These are motor driven to provide the proper pull force to draw the wire stock through the upstream die.

Question 30

Define: Tube Sinking

Answer 30

Way of tube drawing to reduce the diameter or wall thickness of seamless tubes and pipes.

Question 31

Define: Fixed Mandrel

Answer 31

Way of tube drawing in which a long support bar is mounted to establish the inside diameter throughout the operation

Question 32

Define: Floating Plug

Answer 32

Way of tube drawing in which this metal plug’s size matches the natural contour of the reduction zone of the die.