Exam 2 Basic Manufacturing Scott Giese

The defining property of a thermoplastic polymer is that it can be heated from a solid state to a viscous state and then cooled back down to solid, and that this heating and cooling cycle can be applied multiple time without degrading the polymer

true

The die swell ratio for polymer melt has a value that is never less than one

true

The difference between traditional ceramics is that most traditional ceramics are based primarily on silicates such as clay whereas the new ceramics are based on nonsilicates such as oxides and carbides

true

What term refers to the glassy state of a material

vitreous

Curing of elastomers is known as

vulcanization

A thermoforming mold with a convex form is called which one of the following: (a) a die, (b) a negative mold, (c) a positive mold, or (d) a three-plate mold?

a positive mold

In sand casting, the volumetric size of the pattern is _____ the cast part?

bigger than

Use of a parison is associated with which plastic shaping processes?

blow molding

Sand casting is an expendable molding process

true

The total solidification time is proportional to which one of the quantities: where A = surface area of casting, Hf = heat of fusion, Tm = melting temperature, and V = volume of casting?

(V/A)^2

Compared to thermoplastics, thermosetting polymers are characterized by which of the following properties?

- cannot be melted - higher modulus of elasticity - less ductile - capable of higher service temperatures

The principal components of an injection molding machine are which two of the following?

- clamping unit - injection unit

What are properties generally associated with ceramic materials

- high hardness - thermal insulating - chemical stability

Which of the following processes are associated with shaping new ceramics but not normally associated with shaping traditional ceramics?

- hot pressing - isostatic pressing - powder injection molding process

Which of the following properties or characteristics do not apply to metals?

- iconic bonding - high electrical resistivity

What are sections of the conventional extruder barrel for thermoplastics

- metering section - feed section - compression section

What ceramics are commonly used as abrasives in grinding wheels

- silicon carbide - aluminum oxide

An alloy is a metal composed of two or more elements, at least one of which is metallic. The two main categories of alloys are?

- solid solutions - intermediate phases

Properties and characteristics of glass-ceramics include which of the following?

- strong, relative to others - efficiency in processing

A riser in casting is described by

- the source of molten metal to feed the casting and compensate for shrinkage during solidification - removed and not sold to a customer but recycled back into the melt stock

What qualifies as a precision-casting process

-investment casting -plaster-mold casting

Compression molding differs from injection molding in

-presses are oriented vertically rather than horizontally -mold is simpler

If you were given an 8620 steel, the carbon content is

0.20% carbon

Plain carbon steels are designated in the AISI code system by

10XX

At which of the following water contents does clay become a suitably plastic material for the traditional ceramics plastic forming processes

20%

Glass ceramics are polycrystalline ceramic structures that have been transformed into the glassy state

False

Shell molding is best described by

casting process in which the mold is a thin shell of sand bonded by a thermosetting resin

In the casting process a runner is

channel in the mold leading from the downsprue to the gates

Solidification shrinkage in casting is defined as which one of the following?

contraction during the phase change from liquid to solid

The upper part of the sand casting mold is called

cope

As the temperature of a polymer increases, its density

decreases

In rotational molding, centrifugal force is used to force the polymer melt against the surfaces of the mold cavity where solidification occurs

false

Injection molding is a process in which a polymer is heated to a highly plastic state and forced to flow under low pressure into a mold cavity, where it solidifies and is then removed from the cavity

false

The forward movement of polymer melt in an extruder barrel is resisted by drag flow, which is caused by the resistance to flow through the die orifice

false

The oven is used for drying the unfired clay workpiece is called a kiln

false

The press-and-blow process is best suited to the production of narrow-necked beverage bottles, while the blow-and-blow process is more appropriate for producing wide-mouthed jars

false

The strength and hardness of steel increases as carbon content decreases

false

The term green piece in ceramics refers to a part that has been shaped and fired, it hasn't been used yet

false

The process used to produce flat plat glass in which molten glass flows onto the surface of molten tin is called

float process

As the temperature of an amorphous polymer decreases from the liquid state, the polymer changes from liquid to rubbery. As temperature continues to decline, a temperature is reached at which the material becomes hard and brittle. This temperature is called

glass transition temperature

Which of the following metals has the lowest density?

magnesium

A misrun is what type of defect in casting?

metal solidifies before filling the cavity

Glass products are based primarily on which one of the following minerals:

silica

Which one of the following processes or processing steps is not applicable in glass-working?

sintering

Degree of polymerization is

the average number of mers in the molecule chain

Thermoforming is limited to which plastic types

thermoplastics

Which of the three polymer types does not involve cross-linking?

thermoplastics