ME 354 Midterm
The coarse-grained, brittle, and porous structure of a metal prior to it being rolled
Cast structure
Upper half of a sand mold
Cope
Alloys that have high electrical and thermal conductivity
Copper alloys
Inserts made from sand that are placed in a sand mold cavity prior to pouring in order to form hollow regions or otherwise define the interior surfaces of a casting that has internal cavities or passages
Cores
Example for thermoplastic material
Polyethylene
Characterized by being easily stretchable without breaking
ductile
One of the rolling defect
Alligatoring
Example for oxide ceramic
Alumina
Materials that is used in containers and packaging, Computer, tablet and smartphone casings, aircraft bodies, cooking utensils
Aluminum alloys
Glass transition temperature generally refers to
Amorphous polymers
Crystal structure of Martensite
BCT
Bulging of workpiece's surface during compression; it results from the friction between the workpiece and the dies compressing it and also the temperature differentials within the workpiece;
Barreling
A product of the first hot-rolling operation that usually has a square cross section of less than 6" on a side; it is later processed by shape rolling into various shapes such as round rods and bars
Billet
The least expensive of all structural metals; steels containing few or no alloying elements besides carbon
Carbon Steels
The pouring of molten metal into a mold cavity, its subsequent solidification, and its removal from the mold; the part produced by such a process
Casting
An interface in a casting that lacks complete fusion because of the meeting of the two streams of liquid metal from different gates
Cold shut
Die casting process for high-melting-point parts in which the molten metal comes from a more distant source and is poured by ladle into the casting machine
Cold-chamber process
Rapid growth perpendicular to the casting surface; Grains grown opposite to the heat transfer out through the mold;Grains grow preferentially, long and thin, highly directional
Columnar zone
Narrow passages placed in a mold to carry off gases produced when the molten metal comes in contact with the sand in the mold and core
Vents
A very narrow cylinder of metal or other material that is a typical output from. a drawing process
Wire
Example for natural composite
Wood
The fine-grained structure of a metal after is has been rolled; it has enhanced ductility, strength, and hardness
Wrought structure
Small, hard particle having sharp edges and an irregular shape; it is capable of removing small amounts of material from a surface through a cutting process that produces tiny chips; it is used in finishing processes for very hard metal, and ceramic
abrasive
Use of a highly-focused, high-velocity jet of air, nitrogen, or carbon dioxide containing abrasive particles aimed at a workpiece surface for the purposes of material removal; it can be used for cutting intricate patterns in very hard or brittle metallic and nonmetallic materials and for deburring, trimming, removing oxides or other surface films, and cleaning components with irregular surfaces
abrasive jet machining
Process similar to water jet machining except that abrasive particles are included in the fluid, increasing the rate of material removal
abrasive water jet machining
Adding of two or more chemical elements together, at least one of which is a metal
alloying
Examples for conventional abrasives
alumina and silicon carbide
Material exhibits different mechanical properties in different directions
anisotropy
A heat treatment process for the restoration of a cold-worked or heat-treated alloy to its original properties
annealing
Process of heating glass to a certain temperature and then cooling it at a slow rate to relieve residual, internal stresses;
annealing of glass
The spraying of a jet of water or air on a stream of liquid metal that is being poured in order to produce a metal powder
atomization
A method of mechanical comminution to obtain fine particles
ball milling
Bulging of specimen's cylindrical surface during a compression test
barreling
Lathe frame; main structural component that supports all other components of a lathe; it is often made of cast iron
bed
Finishing process in which a coated abrasive is formed into a belt or loop and attached to powered wheels that continuously rotate the loop against a stationary workpiece, allowing for "automatic" removal of material from a workpiece without repetitive manual effort
belt grinding
The process of forcing a piece of sheet metal or other object from a straight form into a curved or angular one
bending
Additive manufacturing process which uses a focused energy source, such as laser or electron beam to melt a material which is simultaneously deposited by a nozzle
directed energy deposition
Slip is cast over a moving plastic belt, while its thickness is being controlled by a blade
doctor-blade process
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
draw beads
Process Used to create a round hole, usually by means of a rotating tool that has two cutting edges
drilling
phase in the production of ceramic parts in which the workpiece loses moisture and shrinks by as much as 20% from the original; the product of this process is in a green state
drying
Variation of casting that is important for the electronics industry; it involves the casting plastic material around an electrical component (1.g. a transformer) to embed it in the plastic which serves as a dielectric
potting and encapsulated
Discrete process for making glass items in which a "gob" of molten glass is placed into a mold and pressed into a confined cavity with a plunger; it is similar to closed-die forging; parts have greater dimensional accuracy than in blowing
pressing
Removal of a layer of material from the surface of a workpiece by a rotating cutter
slab milling
General term used to describe undesirable compounds of oxides that can form on a workpiece's surface during welding
slag
Suspension of colloidal ceramic particles in a liquid (generally water) that is used for casting ceramic parts
slip
Extrusion performed at a high temperature; the high temperatures increases the metal's ductility and reduces the forces needed for extrusion
Hot extrusion
Alloys have high strength and corrosion resistance at elevated temperatures, Used in high temperature applications, jet engine components, rockets, and nuclear power plants
Nickel alloys
One of the two main kinds of rolling in which the cross section of a long workpiece is changed by a set of specially designed rolls; I-beams and railroad rails can be made by this process
Shape rolling
An expendable-mold, permanent-pattern casting process that works as follows: (1) a pattern made of ferrous metal or aluminum is heated, coated with a parting agent, and clamped to a box or chamber that contains fine sand mixed with a resin binder in the bottom; (2) the box is rotated upside down to allow the sand+resin to coat the pattern; (3) the box is heated which hardens the sand+resin into a shell; (4) the shell is removed from the pattern using ejector pins; (5) two half-shells are made by applying steps 1-4 in succession; (6) the two half-shells are clamped together to make the mold
Shell mold casting
Crystal structure of cementite
orthorhombic
A heat treatment process where the part is quickly cooled in water
quenching
Number of slip systems in an ideal close packed hexagonal structure is
3
Crystal structure of alpha ferrite
BCC
Alloy of copper and tin
Bronze
Commercial name for Aramid fiber
Kevlar
Example for Elastomer
Natural rubber
Stronger constituent of a composite is
Reinforcement
Process for forming thermoplastic sheets or films over a mold through the application of heat and pressure; it is commonly used to make advertising signs, cookie and candy trays, panels for shower stalls, and packaging
thermoforming
Diagram relevant to heat treating processes that shows the relationships among temperature, time, composition, and phases present in a particular alloy system that is not at equilrbrium
time-temperature-transformation (TTT) diagrams
Fibers that are produced itself as composites
Boron
Alloy of copper and zinc
Brass
A permanent-mold casting process in which hollow cylindrical parts are made by pouring molten metal into a rotating mold; various designs on the external surface may be cast but the internal surface remains cylindrical; because of density differences, lighter elements tend to collect on the casting's inner surface
Centrifugal Casting
A permanent-mold casting process for parts of any shape in which molten metal is poured onto the center of a rotating table and the molten metal is then forced into smaller molds at the table's edges by centrifugal forces
Centrifuging
An expendable-mold, permanent-pattern casting process similar to plaster mold casting except that it uses refractory mold materials so that metals with a higher melting point (e.g. steel) can be cast; cast parts have high dimensional accuracy and good surface finish
Ceramic mold casting
Defect in extrusion that occur due to plastic deformation zones at the die opening do not meet
Chevron cracking
Rapid nucleation that occurs when the molten metal comes into contact with the cold walls of the mold, forms a narrow band of randomly oriented crystals on the surface of a casting
Chill zone
Rapid nucleation that occurs when the molten metal comes into contact with the cold walls of the mold; Forms a narrow band of randomly oriented crystals on the surface of a casting
Chill zone
Components placed beside or inside mold cavities prior to pouring that aid with the solidification of a casting; their purpose is to increase the rate of solidification in the thicker regions of a casted part and thereby reduce its porosity
Chills
Parts are placed in regions where there is a larger volume of metal to eliminate porosity caused by shrinkage during casting
Chills
Time required for a molten metal to solidify during casting; C*(volume/surface area)^n where C accounts for the mold material, metal properties, and temperature and n is usually assumed to be 2
Chvorinov's rule
Open-die forging operation in which the thickness of a bar is reduced by successive forging steps at specific intervals
Cogging
A closed-die forging process used in the minting of coins, medallions, and jewelry
Coining
Extrusion performed at a room temperature, improves strength due to work hardening, better surface finish and dimensional accuracy
Cold extrusion
A rolling operation which is carried out at room temperature; during this phase, the metal is further strengthened, hardened, and given a better surface finish
Cold rolling
Portion of a chamber where metal is almost stationary prior to flowing through the die in an extrusion process; it is usually located in the corners of the chamber that are closest to the die opening
Dead metal zone
The ratio of molecular weight of the polymer to the molecular weight of the repeating unit
Degree of polymerization
The portion of a machine that acts as an impression for a workpiece and gives the workpiece its shape in a forging or stamping operation
Die
The extrusion process that involves placing a billet in a chamber (container) and subsequently forcing it through a die opening by a hydraulically driven ram; billet is extruded in the same direction as the extrusion force (ram).
Direct extrusion
The difference between the initial and final thickness of a workpiece in flat rolling
Draft
Lower half of a sand mold
Drag
The pulling of material through a die in order to reduce or change its cross sectional area; the material's cross section is usually smaller than in an extrusion process
Drawing
Component placed at the end of a pressing stem in a hydraulic press that serves as a temperature buffer between the pressing stem and the workpiece·
Dummy block
Example for thermosets
Epoxy
An expendable-mold, expendable-pattern casting process in which (1) polystyrene patterns are automatically produced in an aluminum die, (2) the pattern is dipped in or coated with a water-based refractory slurry, dried, and placed in a flask, (3) the flask is filled with sand which is compacted, and (4) molten metal is poured into the mold, vaporizing the pattern as it fills the mold cavity and completely replacing the space previously occupied by the polystyrene
Evaporative pattern casting / Lost foam process
Molds are used for one production cycle only
Expendable Molds
General type of casting in which a single pattern is used to make multiple identical molds which are destroyed/broken apart each time a part is produced
Expendable-mold, Permanent-pattern casting
General type of casting in which one pattern is consumed for each mold produced and the mold is destroyed/broken apart each time a part is produced
Expendable-mold, expendable-pattern casting
The pushing of material under pressure through a die in order to reduce or change its cross sectional area; the output typically has a constant cross section
Extrusion
Angle at which the outer surface of a billet becomes narrower as the billet approaches the die gap in an extrusion process
Extrusion angle
Ratio of original cross sectional area to the final cross sectional area
Extrusion ratio
Crystal structure of Austenite
FCC
One of the two main kinds of rolling in which the thickness of a long workpiece is reduced
Flat rolling
The lightest engineering metal available; it has good vibration-dampening characteristics
Magnesium
Capability of a material to undergo deformation in forging without cracking
Forgeability
The process of shaping a workpiece by applying compressive forces through various dies and tooling; it is one of the oldest metalworking operations
Forging
If insufficient volume of material to completely fill the die cavity, the web may buckle and develop laps
Forging defects
Facility where casting operations are carried out either on a large or small scale; the two kinds of activities that take place are (1) pattern and mold making and (2) melting and pouring of metal
Foundry
Portion of a runner through which the molten metal enters the mold cavity in a standard gravity-casting system
Gate
Material that contain at least 50% silica
Glass
Example for carbon based ceramic material
Graphene
Mixture of Sand + Clay + Water
Green-sand molds
Forging operation performed on the end of a round rod or wire in order to increase the cross section; it is used in the manufacturing of nails, bolt heads, screws, rivets, and various other fasteners
Heading
A rolling operation which is carried out between 450 and 1650 degrees Celsius; during this phase, the coarse-grained, brittle, and porous structure of the input metal is broken down into a wrought structure with finer grain size and enhanced strength and hardness
Hot rolling
Die casting process for low-melting-point parts in which the molten metal comes from a furnace that is an integral part of the casting machine
Hot-chamber process
General forging operation where the workpiece takes the shape of the die cavity while being forged between two shaped dies, during deformation, some of the material flows outward and forms a flash which is subsequently trimmed off
Impression die forging
Extrusion process in which a hollow ram pushes the die back through a stationary and confined billet; billet material flows opposite to the direction of the extrusion force (through the center of the ram)
Indirect extrusion
An expendable-mold, expendable-pattern casting process in which (1) a wax pattern is produced, (2) the pattern is given an initial coat by being dipped in a very fine refractory slurry, (3) the initial coat dries, (4) the pattern's coat is thickened by repeatedly dipping it in stucco (a mixture with larger particles), (5) the pattern + mold is air-dried and placed upside down, (6) the one-piece mold is heated to melt out the wax pattern, (7) the mold is fired at a high temperature, and (8) metal is poured into the mold
Investment casting / Lost wax process
Forging operation in which the dies are heated to the same temperature as that of the hot workpiece
Isothermal forging
Compression in the middle and tensile on the surfaces
Large rolls or draft
Relatively high heat intensity welding process
Laser beam
Metal used for radiation shielding against X-rays
Lead
In composites, directionally dependent properties are due to
Long fibers
Lead, zinc and tin
Low melting alloys
These alloys do not have regular crystal structures or grain boundaries but rather their atoms are packed randomly and tightly
Metallic glasses
A hollow form used in casting for giving a particular shape to something in a molten state; it often has two parts that are clamped together
Mold
The workpiece velocity is equal to the rolls surface velocity, therefore there is no slipping between the workpiece and the rolls
Neutral point
A rolling process in which a strip of sheet metal is reduced in thickness by a series of successive rolling stations or stands
Tandem rolling
The simplest forging operation in which a workpiece is reduced in height by being compressed between two flat dies; the workpiece remains visible to the outside at all times
Open-die forging
A lubricant - often wax, silicone - used to coat a mold cavity to prevent the molded piece from sticking to it, thus to facilitate removal of the workpiece from the die or mold after casting is complete
Parting agent
The seam between the cope and drag in a sand mold; the seam (e.g. line, plane) between the upper and lower halves of a die or mold
Parting line
A model of the part(s) to be produced by a metal casting process; it is used to make the mold which in turn makes the part; it may have one or two pieces
Pattern
Molds are used in multiple production cycles
Permanent Molds
General type of casting in which the same mold is used repeatedly to make many parts; in this kind of casting, the mold is made from materials with high resistance to erosion and thermal fatigue
Permanent mold casting
Forging process that indents (but does not break through) the surface of a workpiece with a punch in order to produce a cavity or an impression
Piercing
Defect in extrusion that tends to draw surface oxides and impurities towards the centre of billet
Pipe
An expendable-mold, permanent-pattern casting process in which each mold half is made of a plaster of Paris (i.e. gypsum, calcium sulfate, CaSO4)-based slurry that (1) is poured over the pattern half, (2) sets, (3) is removed from the pattern, and (4) is dried at about 200 deg. Celsius; cast parts have high dimensional accuracy and good surface finish but cannot have a high melting point and therefore are usually made of aluminum, magnesium, zinc, or copper
Plaster mold casting
Phenomenon whereby small holes or empty spaces exist in a casting due to shrinkage or the dissolving of gases in the casted part; it is detrimental to the ductility and surface finish of a casted part
Porosity
Gold, silver and platinum
Precious metals
Large machine for forging or sheet metal forming in which the material is slowly condensed into a shape by applying continuous pressure; there are two dies--one stationary and one pushed towards the other, which compresses the part; the amount of time the dies are in contact with the workpiece is measured in seconds (as compared to the milliseconds of a hammer forge)
Press
A permanent-mold casting process in which molten metal is forced into the mold by positive gas pressure, the pressure is maintained until the metal has completely solidified, Vacuum maybe used to force the molten metal into the mold and removes dissolved gasses
Pressure casting
Metals with very high melting points including molybdenum, niobium, tungsten, and tantalum
Refractory metals
The synthetic chemical used to bind the sand together in a sand casting operation
Resin
Melt flow characteristics, such as laminar or turbulent flows, can be determined using
Reynolds Number
A rolling process in which a thick ring is expanded into a large-diameter thinner one; it can be used to produce large rings for rockets, turbines, jet engine cases, gearwheel rims, etc.
Ring rolling
Reservoir for storing molten metal in a standard gravity-casting system that supplies the molten metal necessary to prevent porosity due to shrinkage during solidification
Riser
A narrow cylinder of metal or other material that is a typical input for a drawing process
Rod
These alloys return to their original shape upon heating after being plastically deformed into various shapes at room temperature
Shape memory alloys
Horizontal channel in a standard gravity-casting system that carries molten metal from the sprue towards the mold cavity
Runner
An example for 'incomplete casting' defect in castings
Runouts
A low-cost, expendable-mold, permanent-pattern casting process in which silica sand (SiO2) is used as the mold material; casted parts have a relatively coarse surface finish
Sand casting
Machine that automatically compacts sand around a pattern, thereby producing the two halves of a sand mold
Sand molding machine
An increase in specific density (density/volume) of the material
Shrinkage
Tensile in the middle and compression on the surfaces
Small rolls or draft
Tapered vertical channel through which molten metal flows downward after it leaves the pouring basin in a standard gravity-casting system
Sprue
Molten metal is poured into die cavity and allowed to solidify under high pressure applied by a punch having the mold shape. The part is then ejected from the die by ejector pins
Squeeze casting
Steels with high corrosion resistance, strength, ductility, and chromium content (of at least 10%); steels that develop a thin, hard, adherent film of chromium oxide that protects the metal from corrosion in the presence of oxygen/air
Stainless steels
Defect in extrusion that occur due to very high extrusion temperature, friction or speed
Surface cracking
Polymers that soften when heated and they return to original strength and hardness when cooled and the process is reversible
Thermoplastics
Polymers that do not become soft on heating and they never melt once set
Thermosets
A cold-rolling process in which straight or tapered threads are formed on round rods or wire
Thread rolling
Material that are generally used in orthopedic implants
Titanium alloys
The removal of the flash during the final phase of a multi-phase closed-die forging process
Trimming
Closed-die forging in which flash does not form and the workpiece completely fills the die cavity
True closed-die forging
Additive manufacturing process in which an ink-jet mechanism deposits a liquid droplets of inorganic binder material onto a layer of polymer, ceramic, or metallic powder; a piston supporting the powder bed is lowered incrementally, and with each step, a layer is deposited and then fused by the binder
binder jet printing
Class of materials added to powder mixture to improve the green strength
binders
Workpiece that is cut from sheet metal by shearing and is the starting material for further manufacturing operations
blank
Component used to hold down the workpiece during a deep drawing process
blankholder
Step 2 in the powder metallurgy process; in this step, one or more powders of differing compositions and particle sizes are mixed under controlled conditions; lubricants and binders may also be mixed
blending
Discrete process for making hollow and thin-walled glass items, such as bottles, vases, and flasks) in which blown air expands a hollow "gob" of heated glass against the inner walls of a mold; the mold is usually covered with a parting agent; it is somewhat difficult to control wall thickness, but the surface finish is acceptable for most items such as bottles and jars
blowing
Crystal structure in which atoms are centered in the eight corners of a cube and also in the center of the cube
body centered cubic
Machining process used to enlarge a hole made by a pervious process
boring
Machining process that uses a toothed tool to remove material; use of a long multiple-tooth cutter to machine internal and external surfaces such as holes of circular, square, or irregular section
broaching
Undesirable result when layers of material from a workpiece that are gradually deposited on the tool tip in a cutting process; as it grows larger, it suddenly breaks apart only to start reforming again in a cycle of formation and destruction; it is generally undesirable because it changes the geometry of the cutting edge and dulls it
built-up edge (BUE)
An undesirable thin, sharp edge or ridge on a workpiece that results from its shearing; it can often be filed off manually
burr
Forming rubber sheets by feeding incoming molten material through a series of rolls
calendering
Large assembly or tray that slides along the ways and is usually on top of the center portion of a lathe; it consists of tool post upon which the cutting tool is mounted, a cross slide that moves (radially) in and out (perpendicular to the ways) to control the distance from the cutting tool to the center of the part being turned, and a front panel (i.e. apron) on which the controls for both the manual and automatic movement of the carriage reside
carriage
Hardening of the surface of a part
case hardening
A family of ferrous alloys composed of at least 90% iron, 2.11%-4.5% carbon
cast Iron
Plastic forming method for ceramics in which a clay mixture (20-30% water) is forced through a die opening by a screw-type piece of equipment
ceramic extrusion
Cutting tool vibration during machining that is caused by the interaction of the chip-removal process with the structure of the machine tool
chatter
Process also known as etching, this is a general term for a removal of material form a part when it is immersed in a corrosive fluid, selective attack by the fluid on different areas of the workpieces surface is controlled by adding and removing layers of a material called masking; it is the oldest of the advanced machining processes and is used for engraving metals and in the production of printed circuit boards and microelectronics devices
chemical machining
Important finishing process for the electronic industry in which a polishing pad+table and a suspension of abrasive particles in a water-based solution are used to remove material from the workpiece through combined corrosion and abrasion
chemical-mechanical polishing
Small piece of material removed from the surface of a workpiece during machining
chip
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
chip breaker
Workholding device on a lathe that tightly clamps a cylindrical end of a workpiece to the spindle using three or four jaws
chuck
The horizontal distance between the punch and die in a sheet metal shearing operation
clearance
A compaction process in which (1) a metal powder is placed in a flexible rubber mold, (2) the assembly is pressurized hydrostatically in a chamber for an extended time, usually using water, and (3) the assembly is removed; this process achieves more uniform compaction than a press
cold isostatic pressing
Plastic deformation of a metal at a temperatures less than 30% of the metal's melting point
cold working
Step 3 in the powder metallurgy process in which blended powders are formed into various shapes using mechanical or hydraulic presses, isostatic pressure systems, injection molding systems, or other means; in this step, the goal is to produce parts of the required shape, density, and particle-to-particle contact so they are sufficiently strong to undergo further processing
compaction
Process for forming thermosetting plastic materials--that is similar to the closed-die forging of metals--in which premeasured amount of starting powder or viscous liquid is placed directly into a heated mold cavity and the material is formed under the pressure from the upper half of the die; flash is removed afterward by trimming; it is used to produce dishes, handles, container caps, fittings, etc.
compression molding
Bond between two atoms in a molecule in which electrons in outer orbits are shared by atoms
covalent
Wear takes place on the tool rakeface where the chips slide during the removal process
crater wear
Permanent elongation of a component under a static load maintained for a period of time
creep
Examples for super abrasives
cubic boron nitride and diamond
Process where the tool moves radially inward and separates a piece from the blank; process used to separate a cylindrical part
cutting off
General sheet metal forming process in which a punch forces a flat sheet-metal blank into a 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
deep drawing
Additives used to make ceramic-water suspension more uniform
deflocculant
Speed at which the specimen being stretched
deformation rate
Material's mass per unit volume
density
The formation of bonds between adjacent powder particles during sintering that results from the movement of atoms in a solid state across the interface
diffusion bonding
Temperature at which solidification begins when an alloy is cooled
liquidus
General term for the removal of material by melting small portions of a workpiece by a spark; also called spark erosion machining; in the most common version, the (usually metal)workpiece and a tool in the shape of the cavity to be formed are both immersed in a dielectric fluid and connected to a DC power supply; when the potential between the workpiece and tool is sufficiently high, the dielectric breaks down and a short-lived spark discharges through the fluid, removing a very small amount of material from the workpiece surface
electrical discharge machining
Combination of electrochemical machining with conventional grinding; the equipment is similar to a conventional grinder except that the wheel is a rotating cathode embedded with abrasive particles
electrochemical grinding
General term for the removal of material from a workpiece by the action of an electrical power source and ion transfer inside an electrolytic fluid; it is essentially the opposite of electroplating; metal ions are washed away from the surface of a workpiece (the anode) via a pump that circulates electrolyte fluid fast enough so the metal ions do not have the chance to plate themselves onto the tool (the cathode); the tool is the same shape of the cavity that is produced in the workpiece it is generally used to machine complex cavities and shapes in high-strength materials and does not leave burrs
electrochemical machining
Piece of metal that acts as an interface between an electrical wire and another medium such as the ionic solution n an electrolytic cell
electrode
Liquid or gel containing ions that can be decomposed into their metallic or other elements via running a direct electric current through the solution with the help of two electrodes - an anode and a cathode
electrolyte
Machining in which high-velocity electrons strike a workpiece surface and generate heat, melting the workpiece; it must be done in a vacuum
electron beam machining
Additive manufacturing process similar to selective laser sintering in which the energy in the form of electron beam is used to melt metal powder to make metal prototypes; the workpiece is produced in a vacuum; unlike SLS, fully dense parts are produced
electron beam melting
Cutting fluids that are a mixture of oil and water and additives that are typically used for high-speed operations because the temperature. rise is significant; the water acts as a good coolant and the presence of oil reduces the tendency of water to cause oxidation
emulsions
Creation of a cavity in a workpiece by a rotating cutter that travels along a certain depth in the workpiece
end milling
Maximum force (stress) to which a material can be subjected in a cycle without fail, regardless of the number of cycles
endurance limit
Elongation of test specimen in a tension test relative to the specimen's initial length
engineering strain
Ratio of applied force to the original cross-sectional area of a test specimen in a tension test
engineering stress
continuous plastic forming process in which the input pellets are placed in a hopper and fed into the barrel of a screw extruder that forces the plastic through a die; it produces a higher volume of plastics than any other plastic forming or shaping process
extrusion
Two-stage plastic forming process in which (1) a tube or preform is first extruded and then (2) it is clamped into a mold with a cavity much larger than the tube diameter, (3) it is blown outward to fill the mold cavity
extrusion blow molding
Crystal structure of Aluminum
face centered cubic
Failure of a material that results from cyclic stresses
fatigue failure
Advancement of the tool/workpiece with respect to the workpiece/tool surface in one revolution of the workpiece/tool
feed
Polymer melt is extruded through the spinneret and then it solidifies by cooling; it is processed to form continuous filament
fiber spinning
Composite manufacturing process where the fibers are pulled through a resin bath before being wrapped around a rotating mandrel that has the internal shape of the desired fiber reinforced polymer product; the resin is then cured and the mandrel removed
filament winding
Small-scale removal of unwanted material (e.g. burrs) from a surface, corner, edge, or hole that is often done by hand; tools are made of hardened steels
filing
Class of materials added to powder mixture to improve the flow characteristics into the dies
lubricants
Machine on which machining operations are performed
machine tool
Also called sintering, this process involves heating a ceramic part to an elevated temperature in a controlled environment; the part becomes stronger and harder as porosity is reduced and strong bonds between the complex oxide particles in the ceramic are formed; some shrinkage occurs
firing
Wear occurs on the relief face of the tool
flank wear
Continuous process for making flat sheets of glass in which molten glass from the furnace is fed into a long bath in which the glass floats over a bath of molten tin; the glass then moves at a temperature of about 650 degrees Celsius over rollers into another chamber where it solidifies
float method
Material that is coated on a filler metal in order to slow the oxidation of the surfaces of the parts being welded by (A) generating a gaseous shield around the weld zone and (B) dissolving and removing oxides and other undesirable substances from the weld zone
flux
Consumable electrode arc welding process where the electrode is tubular in shape and is filled with flux
flux cored arc welding
Use of expandable polystyrene beads as a raw material to form styrofoam cups, food containers, insulting blocks, and shaped packaging materials (all of which have a cellular structure); polystyrene beads are placed in a mold with a blowing agent and are exposed to heat (usually steam) as a result, the beads expand to as much as 50 times their original size and take the shape of the mold cavity
foam molding
Ability of abrasive grains to break down {i.e. fragment) into smaller pieces; it increases as the grains get larger or have more narrow edges; it is desirable and keeps abrasives sharp during use
friability
Solid state welding process in which a third body often a rotating non-consumable probe that is rubbed against the two surfaces to be joined; the contact pressure causes frictional heating up to 230 to 260 degrees Celsius and the probe at the tip of the rotating tool forces mixing of the material at the joint; no shielding gas or surface cleaning is required
friction stir welding
Solid state welding process in which the heat required for welding is generated through friction at the interface of the two surfaces to be joined; typically one workpiece remains motionless and the other is placed in a collet or chuck and rotated at a high constant speed; the two parts to be joined are then brought together by pushing their ends together;-the part that rotates must have rotational symmetry; flash is usually formed in the region of the weld and can easily be removed by machining or grinding
friction welding
Additive manufacturing process in which a robot-controlled extruder head moves in two principal directions over a table, which can be raised or lowered as needed, and a polymer filament is deposited to produce a part slice by slice
fused deposition modeling
Peak tensile stresses develop in the following region of weldment
fusion zone
Consumable electrode arc welding process in which shielded gas is supplied through electrode
gas metal arc welding
Non-consumable electrode arc welding process
gas tungsten arc welding
Continuous process for making flat sheets of glass in which molten glass is squeezed between powered rollers that may have a textured surface.to give the glass a pattern; the glass surface becomes a replica of the roll surface
glass rolling process
Molten glass is wrapped around a rotating hollow mandrel and is drawn out by a set of rolls; air is blown through the mandrel to keep the tube from collapsing.
glass tubing
Coating that is added to ceramic products to improve their appearance· and strength and to make them impermeable; it forms a glassy coating after firing and is usually the final substance added to a ceramic during its production
glaze (enamel)
A workpiece that has undergone the first three steps of the powder metallurgy process but not steps 4 or 5
green compact
Measure of the size of an abrasive grain (10 = large and coarse; 100 = medium sized and fine; 500 = small and very fine)
grit number
Composite manufacturing process where resin and reinforcement are placed in proper order, brushed with a liquid monomer, shaped in the mold by hand using a roller, squeezing action of the roller expels any trapped air bubbles while contact the part, part is cured and removed from the mold surface
hand layup process
Capability of alloy to be hardened by heat treatment
hardenability
Resistance of a material to permanent indentation
hardness
Lathe component that is fixed to the upper left portion of the bed and is equipped with motors, pulleys, and belts that supply power to the spindle at various rotational speeds
headstock
Portion of the base metal with properties that have been altered by its proximity to the weld metal during a fusion welding process
heat affected zone
Manufacturing operation used to improve the surface finish of holes produced by processes such as boring, drilling, and internal grinding
honing
place where plastic pellets, granules, or power are inserted into a loaded into an extrusion machine
hopper
Characteristic of cutting tool material that means it remains hard, strong, and resists wear at high temperatures
hot hardness
A compaction process in which (1) a metal powder is placed in a mold made of high-melting-point sheet steel, (2) the assembly is pressurized in a chamber containing argon or another inert gas for an extended time under high temperatures, and (3) the assembly is removed; this process yields parts of very high quality but is costly and time consuming, so it is reserved mainly for expensive parts such as for the final densification of cutting tools and tool steels and for superalloy components for the aircraft and aerospace industries and in military, medical, and chemical applications
hot isostatic pressing
Combining two or more machining processes into one system to take advantage of the capabilities of each process
hybrid machining
The adding of fluid to a part after it has been sintered in order to take advantage of the part's porosity and produce a finished part with special properties (e.g. a part that does not need to be greased)
impregnating
The rotation of a cutting tool insert in its holder in order to change the cutting edge
indexing
Powder metallurgy process performed after sintering in which (1) a slug of a lower-melting-point metal is placed in contact with a sintered part, (2) the resulting assembly is heated to a temperature high enough to melt the slug, and (3) the molten metal infiltrates the pores of the sintered part by capillary action; it produces a relatively pore-free part having good density and strength and better hardness than the sintered part alone
infiltration
similar to hot-chamber die casting, this process consists of (1) feeding plastic pellets or plastic or granules into a heated cylinder and (2) forcing the melted material into a mold using either a hydraulic plunger or rotating screw system; the mold may have several components including a spruce, runners, cores, and gates; it is widely used to make consumer products such as toys, containers, knobs, and electrical equipment
injection molding
Small, individual cutting tools (often of triangular or square shape) with several cutting edges or points {6 or 8 respectively) that are often clamped on a tool holder via a locking mechanism
insert
Size of the solute atom is much smaller than solvent atom
interstitial solid solution
Bond between two atoms in a molecule in which an electron is transferred from one atom to another
ionic
Procedure for forming ceramic plates in which clay slugs are extruded and formed into a "bat" over a plaster mold, templates or rollers are used to form the bat over the rotating mold, and the part is then fired and dried; the process is confined to axi-symmetric parts, has limited dimensional accuracy, and can be automated
jiggering
Machining process used to produce textures on cylindrical surfaces
knurling
Additive manufacturing process in which (1) a laser beam is used to cut slices on paper or plastic sheets, (2) an adhesive is applied to each sheet, and (3) the sheets are stacked to produce a part
laminated object manufacturing
Leaving a tab in a piece of sheet metal without removing any material
lancing
Machining process in which two surfaces are rubbed together with an abrasive between them, used to-improve the finish of flat; cylindrical, or curved surfaces
lapping
Machining in which the source of energy is a laser; it can be used to cut metallic, ceramic, and plastic parts
laser beam machining
Sintering of mixed powders in which one of the particles has a lower melting point that melts and surround the non-melted powders
liquid phase sintering
Additive manufacturing process similar to inkjet printing in which print heads deposit a photopolymer on the "build tray"; ultraviolet bulbs, alongside the printing jets, immediately cure and harden each layer of polymer, thus eliminating the need for any additional curing
material jetting
Powders of two or more pure metals are mixed by impaction of hard balls, the powders bond together by diffusion and forming alloy powders
mechanical alloying
central region of the barrel in a screw extrusion machine where heat generated by the viscous shearing of plastic pellets and by the external heaters causes melting of the plastic pellets to begin
melt section
Temperature at which a material changes from solid to liquid state
melting
Bond between many atoms in which available electrons are shared by all atoms in contact
metallic
Stress per unit strain of a test specimen that is under elastic stress in a tension test; the slope of elastic portion of stress-strain curve
modulus of elasticity
Die cutting operation in which pieces of various shapes are removed from the edges of a piece of sheet metal
notching
Initial formation of a new crystal at a random locations in a molten metal that is being cooled
nucleation
Reaction of a metal or ceramic with air that results in the formation of a layer of metal oxide on the surface of the metal
oxidation
Die cutting operation in which sheet metal is sheared into two or more pieces
parting
Die cutting operation in which a number of small holes are punched in sheet metal
perforating
A physically distinct and homogeneous portion of a material
phase
Diagram showing the relationships among temperature, composition, and phases present in a particular alloy system at equilibrium
phase diagram
This chemical machining process is used for highly detailed removal of material from flat, thin sheets or fragile workpieces; it consists of the following six stages: (1) the design of the part to be produced is prepared and photographic negative is made; (2) the sheet material is completely coated with photoresist and dried in an oven; (3) the negative is placed over the coated material and exposed to ultraviolet light, which hardens the portion of photoresist that is exposed to the light; (4) the material is "developed", dissolving the areas of photoresist that were not exposed to the light; (Si the blank is then immersed in a bath of reagent which etches away the areas without photoresist; (6) the photoresist is removed and the part is washed
photochemical machining
Use of ionized gas to cut metal sheets and plates; it is much faster than electrical discharge machining and laser beam machining
plasma arc cutting
Appearance of more than one type of crystal structure for a given metal at different temperatures
polymorphism
Machining process performed on a lathe that uses a simple cutting tool to produce an axi-symmetric part (i.e. part with rotational or circular symmetry) whose diameter changes at a non-constant rate along the part's length
profiling
Continuous process for manufacture of fiber-reinforced plastics with constant cross-section where the fibers are pulled through the resin
pultrusion
Shearing operation where the sheared slug is the scrap
punching
A metal in which all atoms are of the same type
pure metal
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
rake angle
Process for producing automotive parts--such as bumpers, steering wheels, and instrument panels--in which a monomer and two or more reactive fluids are forced at high speed into a mixing chamber at a pressure of 10-20 MPa and then into a mold cavity; chemical reactions that join the monomers take place rapidly in the mold, and the resulting polymer solidifies
reaction injection molding
Machining process used to make an existing hole dimensionally more accurate than can be achieved by drilling
reaming
Annealing stage during which the stresses in highly deformed portions of a metal piece are relived
recovery
Annealing stage during which new grains are formed which replace older grains
recrystallization
Angle between the inside surface of the cutting tool and the surface that is being cut in a two-dimensional cutting process
relief (clearance) angle
Stresses that remain within a part after it has been formed and all of the external forces are removed
residual stresses
Resistance welding process in which two opposing rotating wheels or rollers roll along the outside edges of two sheet metals; the rollers are connected to an AC power supply; a spot weld is produced whenever the current reaches a sufficiently high level in the AC cycle; with a high enough current frequency or low enough roll speed, the spot welds actually overlap to form a continuous connection if that is desired; thus, the AC power supply's frequency and current can be controlled in time to make either a continuous weld along the whole length of the connection or weld spots at certain desired locations along the line
resistance seam welding
Resistance welding process in which the tops of two opposing solid, cylindrical electrodes touch a lap joint of two sheet metals, and resistance heating produces a spot weld; it is the simplest and most commonly used resistance welding process;
resistance spot welding
Helical component whose rotation blends plastic pellets and conveys them down the barrel of an extrusion machine towards the die or down the barrel of an injection molding machine towards the mold
rotating screw
Formation of large, hollow parts made of thermoplastics or thermosets within a thin-walled metal mold made in two pieces that is designed to be rotated about two perpendicular axes; om each part cycle, a premeasured quantity of powdered plastic material is placed in the warm mold, the mold is heated and then rotated continuously about its two principal axes, and the powder tumbles against the mold where heat fuses the powder without melting it; it is used to produces garbage cans, buckets, boat hills, large hollow toys, footballs, and carrying cases
rotational molding
Finishing a workpiece by hand using sandpaper
sanding
The use of a blade with many small teeth to cut a workpiece into two or more pieces
sawing
Additive manufacturing process in which a high-powered laser beam sinters non-metallic or metallic powders selectively in a desired pattern; first, a thin layer of powder is deposited in the part-build platform and then the computer-controlled laser beam is focused on that layer, tracing and sintering a particular cross section into a solid mass; the part-build platform is slightly lowered, a new layer of powder is added to the platform, and the process repeats; the part does not require further curing
selective laser sintering
Consumable electrode arc welding process in which an electric arc is generated by touching the tip of a coated electrode against the workpiece and withdrawing it quickly to a distance sufficient to maintain the arc; the end of the electrode and its coating melt in this process and the melted electrode coating deoxidizes the weld area and provides a shielding gas to protect it from oxygen and the environment;
shielded metal arc welding
Step 4 in the powder metallurgy process in which the green compacts are heated in a controlled-atmosphere furnace to a temperature below the melting point, but sufficiently high to allow bonding (fusion) of the individual particles
sintering
Most common casting process for ceramics in which the slip is pored into a porous mold (typically made of plaster or paris), the mold absorbs some of the water from the outer layers of the slip, the mold is inverted and the remaining suspension is poured out, leaving a hollow product; mold and equipment costs are low but dimensional control is poor and the production rate is low
slip casting
Cutting of sheet metal using a pair of circular blades in a manner similar to a can opener
slitting
Temperature at which solidification is completed when an alloy is cooled
solidus
Major element in a solid solution
solute
Minor element in a solid solution
solvent
Energy required to raise the temperature of a unit mass of a material by 1 degree
specific heat
The ratio of modulus of elasticity to density
specific stiffness
The ratio of ultimate tensile strength to density
specific strength
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)
spinning
Tendency of a workpiece to return to its original shape after undergoing a bending operation
springback
A family of ferrous alloys composed of at least 90% iron, and 0.008%-2.11% carbon
steel
Additive manufacturing processes in which a computer controlled laser-focusing system cures a liquid polymer containing a photosensitive curing agent; it begins with a platform that is just barely immersed in a vat filled with liquid photopolymer;_ each layer is formed by focusing the laser on a portion of the surface of the liquid; the portion touched by the laser hardens and a layer is completed, the platform is lowered sufficiently to cover the cured (hardened) polymer with another layer of liquid polymer and the sequence is repeated; once the part is completed, it is subjected to a final curing cycle in an oven
stereolithography
Consumable electrode arc welding process in which the weld arc is shielded by a granular flux that is fed into the weld zone from a hopper by gravity flow through a nozzle; the thick layer of flux completely covers the molten metal, preventing spatter and sparks, and acting as a thermal insulator that promotes deep penetration of heat into the workpiece;
submerged arc welding
Size of the solute and solvent atoms are similar
substitutional solid solution
Manufacturing processes that involve material removal from a workpiece
subtractive processes
Lathe component that slides along the ways and is usually on top of the right side of a lathe; it can be clamped/fixed at any position along the ways and is equipped with a center (i.e. small. conical protrusion) that supports the right end of a long workpiece that is being turned in a lathe
tailstock
Machining process performed on a lathe that produces a conical part or conical portion of a workpiece
taper turning
Machining process used to produce external or internal threads
tapping
A heat treatment process to increases ductility and toughness in which parts are heated to a temperature less than the annealing temperature and then cooled
tempering
In engineering stress-strain curve, necking begins at
tensile strength
Rate at which heat flows within and through a material
thermal conductivity
Changing the dimension of a material as its temperature increases
thermal expansion
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 wear
Test of material strength in which specimen is subjected to shear stress introduced by twisting
torsion
Area under true stress-true strain curve; amount of energy per unit volume that the material dissipates prior to fracturing in a tension test
toughness
Advanced form of compression molding; the uncured thermosetting resin is placed in a heated chamber, then injected into heated closed molds
transfer molding
Single point cutting tool removes material from a rotating workpiece to form a cylindrical shape
turning
Kind of plastic deformation in a crystal in which a portion of the crystal forms a mirror image with itself
twinning
Removal of small amounts of material from a workpiece surface by microchipping and erosion; the workpiece and tool are immersed in a water slurry containing fine abrasive grains and the tip of the tool vibrates up and down with a frequency of 20 kHz and amplitude of 0.01 to 0.07 mm; the vibration gives a very high velocity to the abrasive grains between the tool and workpiece, allowing the grains to remove material from the workpiece; it is best suited for materials that are hard and brittle;
ultrasonic machining
Solid state welding process in which the two surfaces to be joined are subjected to a static normal force and an oscillating shearing (tangential) force; the shearing forces are applied by the tip of a transducer and the frequency of oscillation usually ranges from 10 to 75 kHz
ultrasonic welding
Smallest group of atoms showing the characteristic crystal structure of a particular metal
unit cell
Composite manufacturing process where the use of a vacuum to facilitate resin flow into a fiber layup contained within a mold covered by a vacuum bag, after the impregnation occurs the composite part is allowed to cure at room temperature
vacuum assisted resin infusion/transfer
Composite manufacturing process where a flexible bag is placed over the resin and reinforcing mixture, vacuum is drawn or pressure is applied over the mold, composite is cured at room or elevated temperatures or in autoclave
vacuum/pressure bag molding
Bonds are not classified under primary bonds
van der waals
The mechanism used in s stereolithography whereby the platform can be lowered and raised
vat
The focusing of a jet of water on a workpiece in order to cut it; the water jet acts like a saw and cuts a narrow groove in the material; no heat is produced and it is environmentally friendly
water jet machining
Variation of electrical discharge machining in which a slowly moving wire travels along a prescribed path, cutting the workpiece
wire electrical discharge machining
Force required to permanently deform a specimen in a tension test
yield stress