Term
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Definition
complex internal and external geometries
net/near net shape process
large parts
can use any metal that can be heated to liquid state
possible mass production |
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Term
| open mold vs. closed mold |
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Definition
open-> metal poured until it fills open cavity
closed-> gating system allows metal to flow into cavity |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| where cope and drag separate |
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Term
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Definition
| reservoir that serves as a source of liquid metal to compensate for shrinkage |
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Term
| Total heat required to heat metal to temp sufficient for casting |
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Definition
H=ρV{C(Tm-To)+Hf+Cl(Tp-Tm)
where
ρ=density
V=volume
Cs=weight specific heat for solid
Cl=weight specific heat for liquid
Tm=melting temp
To=ambient temp
Tp=pouring temp
Hf=heat of fusion |
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Term
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Definition
Tts=Cm(V/A)^n
total solidification time required for casting after pouring
Cm is mold constant
n=2 for most cases |
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Term
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Definition
| full scale model of interior surfaces |
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Term
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Definition
Fb=Wm-Wc
where
Wm=weight of displaced molten metal
Wc=weight of core |
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Term
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Definition
(lost wax process) was pattern is coated in refractory material, was is melted away leaving hardened refractory shell, molten metal is then poured into refractory mold
expensive, usually used for small parts, tight tolerances, good surface finish |
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Term
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Definition
casting solidifies completely before filling mold cavity
1) insufficient fluidity
2) pouring temp too low
3) pouring too slow
4) cross section of cavity too thin |
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Term
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Definition
Two portions of metal flow together but lack fusion due to premature freezing
causes similar to misrun |
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Term
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Definition
formation of solid globules of metal that are entrapped in casting
1) splattering (adjust gating system and pouring procedure to reduce splattering) |
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Term
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Definition
depression in surface or internal void
1) solidification shrinkage restricts molten metal available (proper riser design) |
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Term
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Definition
network of small voids throughout
1) localized solidification shrinkage in dendritic structure
usually associated with alloys |
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Term
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Definition
gas cavity at top of part
1) low permeability
2) poor venting
3) high moisture content |
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Term
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Definition
| many small gas cavities at or slightly below surface |
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Term
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Definition
| surface irregularity caused by erosion of mold during pouring |
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Term
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Definition
rough areas on surface due to encrustation of sand and metal
1) portions of mold flaking off during solidification |
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Term
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Definition
molten metal penetrates into the surface of the mold or core, upon solidification, surface contains a mixture sand and metal
1) high fluidity (harder packing of sad needed) |
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Term
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Definition
sideways displacement of cope relative to drag
1) buoyancy of molten metal |
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Term
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Definition
core is displaced, usually vertically
1) buoyancy of molten metal |
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Term
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Definition
crack forms in the mold and liquid metal seeps in, forming a fin
1) insufficient mold strength |
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Term
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Definition
1) thermoplastic
2) thermosetting
3) elastomer |
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Term
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Definition
| Iron‑carbon alloy containing from 0.02% to 2.1% carbon |
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Term
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Definition
| Iron‑carbon alloy containing from 2.1% to about 4.3% carbon |
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Term
| Principal alloying element in stainless steel |
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Definition
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Term
| Use of nickel in stainless steel |
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Definition
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Term
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Definition
| alloy of copper and tin (typical 90% Cu, 10% Sn), widely used today and in ancient times |
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Term
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Definition
| alloy of copper and zinc (typical 65% Cu, 35% Zn) |
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Term
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Definition
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Term
| Important refractory metals |
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Definition
Molybdenum
Tungsten
Tantalum |
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Term
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Definition
contain substantial amounts of three or more metal
Operating temperatures often around 1100C
Applications: gas turbines ‑ jet and rocket engines, steam turbines, and nuclear power plants (all are systems in which operating efficiency increases with higher temperatures) |
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Term
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Definition
in some cases iron is less than 50% of total composition
Alloyed with Ni, Cr, Co |
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Term
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Definition
better high temperature strength than alloy steels
Alloyed with Cr, Co, Fe, Mo, Ti |
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Term
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Definition
40% Co and 20% chromium
Alloyed with Ni, Mo, and W |
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Term
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Definition
| adding additional elements to increase the strength of metals |
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Term
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Definition
strain hardening during deformation to increase strength (also reduces ductility)
Strengthening of the metal occurs as a byproduct of the forming operation |
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Term
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Definition
heating and cooling cycles performed on a metal to beneficially change its mechanical properties
Operate by altering the microstructure of the metal, which in turn determines properties |
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Term
| properties of thermoplastics |
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Definition
Solid materials at room temperature but viscous liquids when heated
Can be easily and economically shaped into products
Can be subjected to heating and cooling cycles without significant degradation: repeatedly |
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Term
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Definition
Cannot tolerate repeated heating cycles
When initially heated, they soften and flow for molding
Elevated temperatures produce: a chemical reaction that hardens the material into an infusible solid
If reheated, rather than soften, thermosets: degrade and char |
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Term
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Definition
extreme elastic extensibility
similar molecular structure to thermosets |
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Term
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Definition
molecules vary in length, so n is an average
mean value of n is DP
DP affects properties of the polymer
Higher DP effects mechanical strength: increase
Higher DP in the fluid state effects viscosity: increases |
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Term
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Definition
Molecular weight (MW) of a polymer is the sum of the molecular weights of the mers in the molecule
MW = n times the molecular weight of each repeating unit |
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Term
| Thermoplastic molecular structure |
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Definition
linear
(some have a branched structure) |
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Term
| Elastomer molecular structure |
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Definition
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Term
| Thermoset molecular structure |
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Definition
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Term
| Effect of increased crystallinity on density |
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Definition
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Term
| Effect of increased crystallinity on stiffness, strength, toughness |
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Definition
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Term
| Effect of increased crystallinity on heat resistance |
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Definition
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Term
| Effect of increased crystallinity on opacity |
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Definition
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Term
| Non-newtonian properties of polymer melts |
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Definition
thinner at higher shear rate
thinner at higher temperature |
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Term
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Definition
rs=Dx/Dd
where Dx= Extrudate diameter
Dd=die diameter |
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Term
| Three zones in an extruder |
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Definition
| feed, compression, metering |
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Term
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Definition
wire meshes supported by a stiff plate containing small axial holes
Purposes:
1) filter
2) build pressure in metering section
3) straighten flow |
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Term
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Definition
Qd = 0.5 π2 D2 N dcsinAcosA |
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Term
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Definition
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Term
| Strategic view of Quality Design and Improvement |
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Definition
| on target with smallest variation |
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Term
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Definition
| Doubling sigma -> 4x cost |
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Term
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Definition
k is number of variables being tested
assume linear output response when changing input
test points only at the extremes - more efficient
ideal for learning the most info with fewest experiments |
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Term
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Definition
Effect of variable 1
average of high minus average of low |
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Term
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Definition
Effect of variable 2
average of high minus average of low |
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Term
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Definition
Compound effect of 1 and 2
average of x1x2 high minus amperage of x1x2 low
(y4+y1)/2-(y3+y2)/2 |
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Term
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Definition
| y = ybar +E1/2*x1 +E2/2*x2 +E12/2*x1*x2 |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
Polymer sheet and film production method
Feedstock is passed through a series of rolls to reduce thickness to desired gauge. |
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Term
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Definition
| heaters located around runner channels which eliminates solidification of sprue and runner |
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Term
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Definition
| Lf = Lo ((1-alpha)(1-beta))^(1/3) |
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Term
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Definition
| Vfinal = V0(1-alpha)(1-beta) |
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Term
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Definition
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Term
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Definition
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Term
| Purpose of gates in injection molding |
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Definition
| constricts flow to decrease viscosity |
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Term
| Molding cavity dimensions |
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Definition
Dc=Dp+DpS+DpS2
Dp=molded part dimension
S=shrinkage value
(Third term corrects for shrinkage in the shrinkage) |
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Term
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Definition
Non-newtonian, shear thinning, thinner at higher temps
Examples:blood, syrup, molasses |
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Term
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Definition
shear thickening, non-newtonian fluid
example: cornstarch in water |
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Term
| Ways to reduce shrinkage in injection molded plastics |
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Definition
1. Add fillers
2. Higher injection pressure
3. Longer compaction time
4. Higher temperature (lower viscosity) |
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Term
| Differences when molding thermosets |
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Definition
1. lower temps
2. shorter barrel length
3. Injected into heated mold to initiate cross-linking |
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Term
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Definition
| starting tube for blow molding |
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Term
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Definition
1. High strength-to-weight ratio
2. Improved fatigue properties
3. Greater toughness
4. Possible to achieve combinations of properties not attainable with traditional materials |
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Term
| Disadvantages of composites |
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Definition
1. Anisotropy can be a disadvantage
2. Weakened by chemicals/solvents
3. Expensive
4. Slow manufacturing methods
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Term
| Components of a composite |
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Definition
Matrix: primary phase
Reinforcing agent: secondary reinforcing phase embeded in matrix (fibers, particles, flakes) |
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Term
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Definition
| mixtures of ceramics and metals, such as cemented carbides |
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Term
| Ceramic matrix composites |
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Definition
| Al2O3 and SiC imbedded with fibers to improve properties |
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Term
| Polymer Matrix Composites |
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Definition
| polymer resins imbedded with reinforcing agents (most typical composites) |
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Term
| What DFA programs quantify |
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Definition
1. Assembly time
2. Manufacturing cost |
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Term
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Definition
| rotational symmetry about an axis perpendicular to axis of insertion |
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Term
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Definition
| rotational symmetry about the axis of insertion |
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Term
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Definition
DFA Efficiency = 3*NM/TM
Where NM is the theoretical minum number of parts
TM = total assembly time |
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Term
| 3 questions of DFA analysis |
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Definition
1. Does this part have to be a different material?
2. Does this part move relative to all other parts?
3. Does this part have to be separate for other parts to work? |
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