midterm 10/17 Flashcards
what does ‘manus’ mean?
hand
what does ‘factus’ mean?
make
what does manufacture mean?
handmade or “made by hand”
what is modern manufacturing?
mechanized or automated equipment that is supervised by human workers
what is technology manufacture?
application of physical and chemical processes to alter the geometry, properties, and/or appearance of a starting material to make parts or products
what is economic manufacture?
transformation of materials into items of greater value by one or more processing and/or assembly operations
what is considered low production?
1 to 100
what is considered medium production?
100 to 10,000
what is considered high production?
10,000 to millions
what are metals composed of two or more elements?
alloys
what is elasticity?
deformation under a load that is not permanent
what is plastic deformation?
permanent deformation after a load is removed
what is stress?
the force applied to a material
what is strain?
the change in length in a material under stress
Which are the two main subdivision of Metals?
ferrous and nonferrous
- true or false?
Turning, welding and bending are considered material removing processes.
false
- true or false?
Forging is considered a deformation process.
true
- true or false?
Particulate processing requires the mixing of metal or ceramic powders with binders, then the powders are loaded in a die with the shape of the desired part to be pressed and finally the part is sintered.
true
what are the main three (3) Chrystal Structures that metal can form into?
- Body-Centered Cubic (BCC)
- Face –Centered Cubic (FCC)
- Hexagonal Closed packed (HCP)
what is the first step in making a risk assessment?
determine the hazard
all but which of the following are protective clothing required for Casting?
cotton coveralls leaving no exposed skin
which of the following is NOT a type of “point of operation” GUARD?
pressure-sensing barrier
what clothing should be NOT be worn when welding?
cotton (natural fiber) gloves
when electric arc welding, what eye protection should you wear?
dark glass with a protective lens
which is not a general hazard associated with welding?
excessive noise
when welding, to minimize the effects of noxious fumes, you should…
assure there is adequate ventilation around the weld sight
what is not a good reason to train employees?
minimizes employee fear of safety hazards
when performing electric arc welding, what is the BEST approach to minimizing the risk of electrocution?
avoid making yourself the circuits easiest path to ground
in a shear press, how are treadles (foot pedals) “guarded”?
With counter weights or springs
what is tensile stress?
material being stretched
what is compressive stress?
material being squeezed
what is shear stress?
material being forced to slide
what is barreling?
increase in area at the middle of the specimen as a consequence of friction with the supporting surfaces
what is hardness?
a material’s resistance to permanent indentation
what is hot hardness?
the ability of a material to retain hardness at elevated temperature (ceramics, tooling materials)
what is viscosity?
resistance to fluid flow
what is fluidity?
ease with which a fluid flows
what is a stamping press?
typical machine tool used
– punch and die (tooling)
what is springback?
when the pressure is removed at the end of the deformation operation, elastic energy remains in the bent part, causing partial recovery of the material towards its initial shape
what is welding?
fabrication process that joins materials using a coalescence process
what are some advantages to welding?
- permanent joint or bond
- weld can be stronger than the parent metal depending on filler
- material
- economical and faster
- not restricted to the factory
- can be mechanized or automated
what are some disadvantages to welding?
- does not allow for convenient
disassembly - labor cost – can be high – requires skills
- can be dangerous
- some quality defects are difficult to detect (internal defects)
- high temp can result in rapid oxidation (rust)
examples of fusion welding?
- Arc Welding
- SMAW (Stick welding)
- GMAW (MIG, MAG, CO2)
- FCAW (Flux-cored)
- SAW (Submerged)
- GTAW (TIG) PAW or PAC (Plasma)
- Resistance Welding
- Oxyfuel Gas Welding
- Electron Beam Welding
- Laser Beam Welding
examples of solid state welding?
- Diffusion Welding
- Friction Welding
- Ultrasonic Welding
what are the five types of welding joints?
- Butt
- Corner
- Tee
- Lap
- Edge
examples of types of welds?
- Fillet
- Groove
- Square
- Single bevel
- “V” groove
- “U” groove
- “J” groove
- Double groove
- Plug
- Slot
- Spot
- Seam
- Flange
- Surfacing
what are the general properties of metals (Physical and Mechanical)?
- high stiffness and strength
- toughness (ability to absorb energy)
- good electrical conductivity (magnetic)
- good thermal conductivity
what are phase diagrams?
graphical means of representing the phases of a metal alloy system as a function of composition and temperature
what is the L phase proportion?
CS / (CS + CL)
what is the S phase proportion?
CL / (CS + CL)
what is the chill zone in casting?
region where the temperature is the coldest (edges in contact with the mold)
what are columnar grains?
elongated grains that grow as the material cools down
what are equiaxed grains?
internal grains that form from additional nucleation at the thickest regions of the cast material
what is diffusion?
a chemical redistribution of atoms in a solid
diffusion can occur either by ________ or by ________.
- heat treatment
- mechanical deformation
what are the main two factors involved during heat treatment?
- time
- temperature (furnace and atmosphere must also be
considered as well as the quenching media)
what is deformation?
hot and cold forming through shaping processes
when setting the shielding gas regulator for the GMAW welding process, which units are used to measure the gas flow?
cfh
which of the following two stainless steels is magnetic? (austenitic vs ferritic)
ferritic stainless
permanent deformation in metal crystals after exceeding the Ultimate Tensile Strength is referred as ________.
non-uniform plastic deformation
the principal alloying element in carbon steel is ________.
carbon
after bending a sheet metal, the part may recover partially towards its original shape after removing the bending pressure.
what two things can be done to counteract this elastic recovery?
bottoming and overbending
what process is a solidification process?
casting
- true or false?
a billet is used to create an extrusion of the die geometry.
true
A manufacturing plant consists of 1)_________ and 2)_________ (and people) to transform a certain limited range of 3)_________ into products of increased value
1) processes
2) systems
3) materials
what are the three building blocks of manufacturing?
- materials
- processes
- systems
what are ferrous metals?
iron based (steel and cast iron)
what are nonferrous metals?
other metallic elements (aluminum, copper, nickel, silver, tin, etc.)
what are crystal structures?
arrangements of atoms, ions, or molecules in a crystalline material
how many distinct crystal structures are there?
7
what is a grain in a block of metal?
an individual crystal
what are three measures of stress?
- elastic modulus
- ductility
- hardness
three types of static stresses?
- tensile
- compressive
- shear
what is density?
weight per unit volume
what is the coefficient of thermal expansion?
measures change in length per degree of temperature
what are the two melting characteristics of alloys?
solidus & liquidus
what is specific heat?
mount of heat to increase the temperature of a unit mass by 1 degree
what is conductivity?
ability to allow current flow
what are the four shaping processes?
- solidification processes
- particulate processing
- deformation processes
- material removal
what are the two steps of solidifcation?
1) casting process
2) cast product
what are the three steps of particulate processing?
1) starting materials are metal or ceramic powders
2) press the materials
3) they are sintered
two ways for deformation processes?
a) forging
b) extrusion
three ways of material removal processes?
a) turning
b) drilling
c) milling
what is the objective of design?
for the product to withstand stresses without changes in geometry
what is the objective of manufacturing?
to transform the material (geometry changes) into a product (by applying stresses that exceed the yield strength of the material)
what is Hooke’s Law?
s = Ee
what variable is for the Modulus of Elasticity?
E
what is necking?
localized elongation that occurs to the right of the UTS
what is fracture stress?
stress calculated just before rupture of the specimen
what is good hardness?
resistance to scratches and wear
most common tests for hardness are the ________ and ________ Hardness tests.
- Brinell
- Rockwell
It is important to know the operating ________ of the product.
temperature
what are the three typical parts of sheet metal?
- enclosures (boxes)
- brackets
- mounting structures (frames)
sheet metal is usually how thin?
1/16” to 1/4”
when sheet metal is above 1/4” thickness, it is referred to as a ________.
plate
what is an ingot?
large size casting produced in a foundry
when the metal product is thinner than 1/4” and has a <24” width, it is known as a ________.
strip
If thick sheet metal, ________ may be used to assist with deformation.
warm working
what are the machine tools used for bending generally called?
presses
what is a stamping press?
typical machine tool used
in mass production, what 2 things are often used?
strips or coils
what are two compensations for springback?
- overbending
- bottoming
what is welding?
a fabrication process that joins materials using a coalescence process, and joins materials (usually metals or thermoplastics) by using high heat to melt the parts together and allowing them to cool, causing fusion
________ and ________ are lower temperature techniques which do not melt the base metal (parent metal).
- brazing
- soldering
examples of fusion welding?
- arc
- resistance
- oxyfuel gas
- electron beam
- laser beam
what does PPE stand for?
personal protective equipment
what are the general properties of metals?
- high stiffness and strength
- toughness
- good electrical conductivity (magnetic)
- good thermal conductivity
Atoms are ________ together making ________.
- bonded
- solid structures
what is a covalent bond?
electron-sharing
what is an ionic bond?
electrostatic forces of attraction and repulsion
what is a metallic bond?
similar to covalent (electron sharing)
what is crystal lattice?
geometric array of points
what is a unit cell?
the smallest subdivision of the lattice
what does BCC stand for? (crystal structure)
body-centered cubic
what does FCC stand for? (crystal structure)
face-centered cubic
what does HCP stand for? (crystal structure)
hexagonal closed-packed
An Alloy is a metal composed of two or more ________ of which one is metallic.
elements
what is the intermediate phase?
a second phase formation beyond the dissolving element limit
what are phase diagrams?
Graphical means of representing the phases of a metal alloy system as a function of composition and temperature
three steps to determine the chemical composition?
1) draw a horizontal line at the temperature of interest
2) where it intersects the solidus and liquidus lines, draw a vertical line to read the composition
3) apply the inverse lever rule
pure iron temperature for Alpha (Ferrite)
room temp
pure iron temperature for Gamma (Austenite)?
912ºC
pure iron temperature for Delta (Ferrite)?
1394ºC
pure iron melting point temp?
1539ºC
low carbon steels have how much carbon?
less than 0.2%
medium carbon steels have how much carbon?
0.2% to 0.5%
high carbon steels have how much carbon?
> 0.5%
what is Eutectic?
solidus and liquidus are at the same temperature
what is Eutectoid?
solid state reaction
what does HSLA mean?
high-strength low-alloy
for stainless steels, principal alloying element is ______ above 15%.
chromium
- true or false?
Austenitic stainless is the most corrosion resistant.
true
five types of cast iron?
- grey cast
- ductile
- white cast
- malleable
- alloy cast
what are refractory metals?
able to endure high temperatures
three examples of precious metals?
- silver
- gold
- platinum
what are superalloys?
- high temperature performance
- tensile strength
- hot hardness
- creep resistance
- corrosion resistance
what is the microstructure of metals?
the size and distribution of a second phase or to the grain size of the principal phase
how is microstructure usually observed?
under a microscope of a flat polished surface of metal that has been etched with chemicals to reveal different features
what is eutectoid microstructure?
generally a platelike structure named pearlite in the case of steel
for casting, what is the chill zone?
region where the temperature is the coldest (edges in contact with the mold)
what are two issues with casting?
1) nonmetallic inclusions may form mainly in the center due to a push that occurs during solidification
2) shrinkage during solidification may lead to voids as the liquid phase occupies less space than the solid phase
what is diffusion?
a chemical redistribution of atoms in a solid
how can diffusion occur?
- heat treatment
- mechanical deformation
what are the two main factors involved during heat treatment?
- time
- temperature
the most basic heat treatment is called __________.
homogenization
what is deformation?
- hot and cold forming through shaping processes
- plastic deformation
- heat treatment of deformed metals may lead to recovery of properties
