IE 350 Exam 2
band saw
a continuous, long, flexible blade that forms a loop with itself and is used to cut sheet metal, metal plates, and other kinds of workpieces
Compound Die
a die that allows several operations on the same sheet to be performed in one stroke of a press
Punch Press
a power-driven machine used to cut holes in metal sheets under pressure
Redrawing
a second pass at deep drawing that is sometimes needed
Eddy Current
an electric current in a conducting material that results from induction by a moving or varying magnetic field
Burr
an undesirable thin, sharp edge or ridge on a workpiece that results from its shearing or machining; it can often be filed off manually
inclination angle
angle between the cutting tool's sharp edge and the line on the workpiece's surface that is perpendicular to the direction of cutting in a three-dimensional cutting process
relief (clearance) angle
angle between the inside surface of the cutting tool and the surface that is being cut in a two-dimensional cutting process
rake angle
angle between the outside surface of the cutting tool and the imaginary plane that is perpendicular to the cutting direction in a two-dimensional cutting process
flanging
bending the edges of a piece of sheet metal, usually to 90 degrees
Flaring
bending the edges of sheet metals to less than 90 degrees
hot hardness
characteristic of cutting tool material that means it remains hard, strong, and resists wear at high temperatures
Inert
chemically unreactive; a diesirbale characteristic in cutting tool material
Double action hydraulic Press
commonly used machine for deep drawing in which the punch and blankholder are controlled independently
blankholder
component used to hold down the workpiece during a deep drawing process
Single minute exchange of die (SPF)
concept that allows for automatic die changes in a sheet metal stamping press in less than 10 minutes using computer-controlled hydraulic or pneumatic systems
Indirect method for cutting tool condition monitoring
correlating a cutting tool's condition with parameters such as cutting forces, power, temperature rise, workpiece surface finish, vibration, and/or chatter
end milling
creation of a cavity in a workpiece by a rotating cutter that travels along a certain depth in the workpiece milling operation that is one of the most important and versatile of all machining operations with the ability to produce various profiles and curved surfaces
Slitting
cutting of sheet metal using a pair of circular blades in a manner similar to a can opener; this is often used to convert a single large steel coil into several coils with smaller width
Titanium carbide
cutting tool materials consisting of TiC particles bonded together in a nickel-molybdenum matrix that are suitable for machining hard materials and cutting at higher speeds than those appropriate for other carbides
Tungsten Carbide
cutting tool materials consisting of WC particles bonded together in a cobalt matrix that are produced using powder metallurgy techniques; cobalt increases the toughness but reduces the strength and hardness of the carbide and its composition ranges from 6-16%
(Cemented or sinntered) carbides
cutting tool materials that were introduced in the 1930s in response to a growing demand for increased strength and hardness at elevated temperatures; they are among the most important, versatile, and cost-effective tool and die materials for a wide range of applications
Perforating
die cutting operation in which a number of small holes are punched in sheet metal
Notching
die cutting operation in which pieces of various shapes are removed from the edges of a piece of sheet metal
Parting
die cutting operation in which sheet metal is sheared into two or more pieces
Lancing
die cutting operation that leaves a tab in a piece of sheet metal without removing any material
feed rate
distance the cutting tool travels horizontally per unit revolution of the workpiece in a turning process (mm/rev); this is also the depth of the cut in a turning process
Chip Breaker
feature incorporated in a cutting tool that assists with the breaking of large or continuous chips so they do not become entangled in the machinery
Max Punch Force
force F required to punch out a blank from sheet metal; = 0.7*T*L*UTS where T is the sheet thickness and L is the total length sheared (such as the perimeter of a hole)
Maximum punch force (in deepdrawing)
force Fmax required in deep drawing; = 3.14*Dp*T*UTS*(Do/Dp - 0.7) where Dp is the punch diameter, T is the blank thickness, and Do is the blank diameter
Maximum Bending Force
force P required to bend a sheet of metal; = k*Y*L*T*T/W where k ranges from 0.3 to 1.3 depending on the die shape, Y is the yield stress of the material, L is the length (i.e. width) of the sheet being bent, T is the thickness of the sheet being bent, and W is the width of the die opening
deep drawing
general sheet metal forming process in which a punch forces a flat sheet-metal blank into a (usually deep) die cavity and the blank takes the form of the die; it is one of the most important metalworking processes in use today; aluminum cans are produced using this process
Die-Cutting
general sheet metal shearing operation that consists of perforating, parting, notching, and/or lancing
machining
general term denoting the removal of material from, and modification of the surfaces of, a workpiece after it has been produced
Stamping
general term for the impressing of sheet metal by a press; sheet-metal part produced by a press
Roughing cut
general type of cutting operation that is deep and with a high feed rate and/or speed in which large amounts of material are removed from a workpiece in a short time with little regard for surface finish
Finishing cut
general type of cutting operation that is shallow and with a low feed rate and/or speed in which a nice surface finish is a priority
Pressworking, press, forming, stamping
generic term used to describe general sheet metal forming operations
tool wear
gradual deterioration of a cutting tool caused by high localized stresses at the top of the tool, high temperatures along the rake face, sliding of chips along the rake face, and sliding of the tool along the newly cut workpiece surface
Tool-life curve
graph of experimental data obtained by performing cutting tests of various materials under different cutting conditions, such as cutting speed, feed, depth of cut, tool machinery and geometry, and cutting fluids
Diffusion Bonding ( Combined with SPF)
important sheet metal forming process for the aerospace industry in which selected locations of two or more sheets are first diffusion bonded while the rest remains unbonded and the structure is expanded into a mold using pressurized argon gas, taking the shape of the mold
flake face
inside surface of the cutting tool in a two-dimensional cutting process
Seaming
joining the edges of two piecces of sheet metal by hemming
machine tools
machine on which machining operations are performed
Thermally assisted machining
machining in which a source of heat (e.g. torch, induction coil, electric current, laser beam, electron beam, plasma arc) is focused onto an area just ahead of the cutting tool; it may enable machining of a metal or alloy that may otherwise be difficult to machine at room temperature
cutting off
machining operation in which a small piece is separated from the main portion of a blank; cutting a piece from the end of a part in order to produce a slug or blank for additional processing into a final product
finish machining
machining where the main consideration is the surface finish to be produced
rough machining
machining where the main purpose is to remove a large amount of material at a high rate
Sheet Metal
metal in sheets or thin plates that is usually shipped in large coils
Oblique
neither perpendicular nor parallel to a given line or surface; slanting; sloping; the majority of machining operations involve this type of cutting
rake face
outside surface of the cutting tool in a two-dimensional cutting process
nesting
placement of part outlines on sheet metal in order to optimize material utilization during a sheet metal blanking operation
cutting tool
portion of a machine tool that removes the material from a workpiece
water-jet cutting
process in which a high-pressure stream of water is used to cut sheet metal or metal plates
Hydroforming (fluid forming)
process similar to rubber forming except that the fluid pressure over the rubber membrane is controlled throughout the forming cycle and the pressures are about ten times as high; uses a high pressure hydraulic fluid to press room temperature working material onto a die
laser-beam cutting
process that uses a laser to cut through sheet metal or metal plates
Shaving
process whereby extra material is removed from an edge that was too rough after having been sheared
Minimum bend radius
radius R at which a crack first appears at the outer fibers of a sheet of metal that is being bent; = T*(50/r - 1) where T is the sheet or plate thickness and r is the tensile reduction of area of the sheet metal in % (i.e. the % reduction in area of the material before it fractures in a tension test (textbook section 2.5))
slab milling
removal of a layer of material from the surface of a workpiece by a rotating cutter peripheral milling in which the (milling) cutter is longer than the width of the cut
Blanking
shearing operation where the sheared slug is the part to be used and the rest is scrap
Punching
shearing operation where the sheared slug is the scrap
Laser Forming
sheet metal forming process in which a laser acts as a localized heat source, creating steep thermal gradients in the workpiece that are enough to cause plastic deformation of the sheet
Rubber Forming
sheet metal forming process in which one of the dies in a set is made of a flexible material whose pressure is controlled by a fluid-filled cavity that is immediately behind it
Stretch forming
sheet metal forming process in which the sheet is (1) gripped along its edges and stretched, (2) broght in contact with a male die, and (3) compressed by the female die to give it its final shape; aluminum skins for sircraft can be made by this method
Draw beads
small components that help to pin the workpiece between the blankholder and die in a deep drawing operation; they are often necessary to control the flow of the workpiece into the die cavity
Chip
small piece of material removed from the surface of a workpiece during machining
box-type pillar structure
structure for sheet metal stamping presses that is stiff and is becoming more widespread as the accessibility of the die and workpiece becomes less important
Springback
tendency of a workpiece to return to its original shape after undergoing a bending operation
Sheet-metal formability
the ability of the sheet metal to undergo the desired shape change without failure
Overbending
the compensation for springback in a bending operation
shearing
the cutting of pieces of sheet metal from a sheet metal coil using a punch and a die
Tube Hydroforming
the formation of metal tubing in a die that is made possible by the exertion of water pressure on the internal surface of the tubing
Spinning
the forming of axi-symmetric parts over a mandrel by the use of various tools and rollers (similar to that of forming clay on a potter's wheel)
Superplastic Forming
the forming of sheet metal that can stretch up to 20 times its original length while maintaining uniform elongation (i.e. without necking); high pressure argon gas is typically used; very complex shapes can be formed out of one piece with fine detail and close tolerances
Clearence
the horizontal distance between the punch and die in a sheet metal shearing operation
Laser-beam butt welding
the joining of two or more pieces of sheet metal of different thicknesses by means of heat that is produced by a laser; it is an important process in the manufacturing of car body components; the output from this process often becomes the input for a stamping process
high-speed steels
the most highly alloyed tool and die steels; steels that are very strong and hard at elevated operating temperatures that are used in cutting tools; they are so named because they were developed (in the early 1900s) to machine at higher speeds than was previously possible; there are two basic types--molybdenum ("M-series" with 10% molybdenum) and tungsten ("T-series" with 12-18% tungsten)
Trim loss (scrap)
the percentage of a piece of sheet metal that is not turned into useful parts during a sheet metal shearing process; it may be up to 30%
Bulging
the pressing on and subsequent widening of a rubber plug which has been placed inside a tubular, conical, or curvilinear part; when the plug widens, it expands the diameter of a limited portion of the workpiece
Hemming
the process of folding the edge of a metal sheet over on itself
Bending
the process of forcing a piece of sheet metal or other object from a straight form into a curved or angular one
Trimming
the removal of excess scrap metal during sheet metal forming
turning
the rotation of a part while it is being machined
Electromagnetically assisted forming
the running of electrical current through a magnetic coil that is placed beside a workpiece made of sheet metal; it creates an eddy current in the workpiece that forces it onto a die or mandrel
Punch
the solid upper portion of a punch press, used with a hollow lower die to blank out shaped pieces of sheet metal or the like
Shot Peening
the spraying or blasting of steel shot with diameter of about 0.1" (as in a shot gun) towards a piece of sheet metal in order to deform it
Explosive forming
the use of explosives as a source of energy for sheet metal forming; after a sheet metal blank is clamped over a die and lowered into a tank filled with water, the die is evacuated and an explosive charge is detonated, generating a shock wave that forces the workpiece onto the die
cutting speed
the velocity of the tool along the surface of (or relative to the surface of) a workpiece that is being cut
Cup
the workpiece as it is sliding down into the die during deep drawing
Independent Variables in cutting process
these include (A) the tool material and coatings, (B) tool shape, surface finish, and sharpness, (C) workpiece material and condition, (D) cutting speed, feed, and depth of cut, (E) cutting fluids, (F) characteristics of the machine tool, and (G) work holding and fixturing
Dependent Variables
these include (A) the type of chip produced, (B) force and energy dissipated during cutting, (C) temperature rise in the workpiece, (D) tool wear and failure, and (E) surface finish and surface integrity of the workpiece
Transfer die
type of compound die in which discrete parts are fed through many stations within the same machine and a different operation is performed at each station of the machine with a single stroke of the ram
Progressive dies
type of compound die in which sheet metal is fed through as a coil strip and a different operation is performed at each station of the machine with a single stroke of the ram
Incremental forming
type of sheet metal forming operation that is related to spinning that does not use a mandrel; in one version, a rotating sheet metal blank is gradually deformed by a steel rod with a smooth hemispherical tip to produce axi-symmetric parts (parts that are symmetric with respect to the axis of rotation); in another version, a computer numerical controlled machine tool is programmed to follow contours at different depths across the sheet metal surface such that the blank is clamped and stationary, and the tool rotates to assist forming
helical
typical shape of the chips in a three-dimensional cutting process
Direct method for cutting tool condition monitoring
using a microscope or other instrument to optically measure cutting tool wear and/or observe changes in the tool shape/profile
(countour, cold) roll forming
using a series of rolls to bend and otherwise form sheet metal with a high productivity rate
Tube bending
variants of this bending process include stretch bending, draw bending, compression bending, and ram bending; mandrels are often used
C-Frame Structure
widely used structure for sheet metal stamping presses that allows greater accessibility to the die and workpiece
Blank
workpiece that is cut from sheet metal by shearing and is the starting material for further manufactuing operations
