CAM 120 Chapter 14

Both automated tape-laying machines and automated fiber placement machines dispense prepregs consisting of continuous fiber bands impregnated with resin. Which machine uses a wider prepreg?

Automated tape laying machine

In compounding and mixing of rubber in preparation for shaping, which of the following additives should be added last?

Valcanizing chemicals, Otherwise, premature vulcanization might occur

Synthetic rubber is supplied to rubber processors in the following forms?

large bales

In reinforced reaction injection molding, two reactive chemicals and short reinforcing fibers are mixed and immediately injected into a mold cavity where curing and solidification of the chemicals occur rapidly.

True

A preform is a mat that has been cut and shaped for closed-mold processes in which it is impregnated with resin and cured to produce a fiber-reinforced molding.

True

Automated tape-laying (ATL) machines dispense a prepreg tape onto an open mold by following a programmed series of back-and-forth passes across the mold surface until the parallel rows of tape complete each layer.

True

Blow molding and thermoforming can be used to produce items made of thermoplastic elastomers.

True

Common resins used in open-mold processes are polyesters and epoxies, using fiberglass as the reinforcement.

True

Pulforming is similar to pultrusion but is capable of producing a semicircular contour with altered cross sections at one or more locations along the length of the part.

True

Resin transfer molding is a closed-mold process in which a preform mat is placed in the mold and a thermosetting resin is transferred into the cavity under moderate pressure to impregnate the preform.

True

The tire is assembled on a machine known as?

building drum

FRP composite molding compounds consist of the resin matrix with short, randomly dispersed fibers; when it is in the form of a billet with diameter 25 to 50 mm (1 - 2 in), it is called?

bulk molding compound

What are two of the following ingredients do not contribute to the vulcanizing process?

calcium carbonate and carbon black

The roller die process is a combination, two of the following processes?

calendering and extrusion

Of the following additives in rubber, which one would rank as the single most important?

carbon black

The internal structure of the tire, consisting of multiple layers of rubber-coated cords, is called?

carcass

Calendering is a rubber-shaping process that uses one of the following types of hardware?

rolls

In the hand lay-up process, a dry layer of fiber reinforcement is placed onto the mold and impregnated by liquid uncured resin using a manual rolling technique; the process is repeated for successive layers.

true

The principal process parameters in curing (cross-linking) of the thermosets used in fiber-reinforced polymer composites are time, temperature, and pressure.

true

The rubber industry is a term that refers to?

companies that produce products of rubber

A molding operation that uses sheet-molding compound is a form of?

compression molding

what is one of the following molding processes is the most important in the production of products made of rubber?

compression molding

two of the following are not normally used in the processing of thermoplastic elastomers?

compression molding and valcunization

Filament winding involves the use of the following fiber reinforcements.

continuous filaments

The color of the natural rubber sheets that have been dried in smokehouses is?

dark brown

The tire is cured in the following points in the production cycle.

during molding

When is the tread pattern imprinted onto the circumference of the tire?

during molding

Most rubber products can be described by three of the following.

elastomer reinforced with carbon black, particle reinforced composite, and polymer matrix composite.

Pultrusion is most similar to which one of the following plastic shaping processes?

extrusion

A positive open mold with a smooth surface will produce a good finish on which surface of the laminated product in the hand lay up method.

inside surface

The following components are present in the belted bias and radial tires but not in the diagonal ply tire.

Belts

A roving is a collection of twisted continuous strands, whereas a yarn is an untwisted collection of filaments

False It's the reverse. A roving consists of untwisted continuous filaments, whereas a yarn is a twisted collection of filaments.

Of the open mold processes for polymer matrix composites, hand lay up is the least labor-intensive.

Hand lay-up is more labor intensive than spray-up or automated lay-up.

A polymer matrix composite is a composite material consisting of a polymer embedded with a reinforcing phase such as fibers or powders.

True

Unlike the hand lay-up method, which is a manual method, the spray-up method can be automated using a multi-axis machine in which the path of the spray gun is preprogrammed and computer controlled to apply successive laminations.

True

Water jet cutting is one of several ways of cutting or trimming uncured or cured FRPs; in the case of cured FRPs, the process is noted for its reduction of dust and noise.

True

Relative to the conventional hand lay-up method, the two are advantages of using prepregs prepared outside the mold and then laid onto the mold surface in successive layers.

closer control over fiber-resin mixture, more efficient method of adding laminations.

two of the following products are not made by hand lay-up open-mold operations

fishing poles and tennis rackets

A following lay-up methods allows for a higher fiber content in the polymer molded product.

hand lay-up

The special tooling in filament winding that determines the shape of the filament-wound part is called?

mandrel

The prepregs applied by automated fiber placement machines are called?

slit tapes and tows

The name of the natural rubber sheets that have been dried in smokehouses is?

smoke ribbed sheet

An advantage of using an open mold versus a closed mold.

the mold costs much less than if two matching molds were used?

the most common polymer type in fiber-reinforced polymer composites.

thermosets

How many minutes are required to cure (vulcanize) a modern passenger car tire?

15lbs

In the spray-up method, is liquid resin is applied on an open mold and chopped fibers are then sprayed onto the resin to build successive FRP laminations?

False, Liquid resin and chopped fibers are sprayed onto the mold at the same time, not sequentially

Recycled rubber is sometimes added as a filler in rubber products, in proportions as high as 25%:

False, The proportions usually do not exceed 10%.

An alternative hand lay-up method involves the use of prepregs that are prepared outside the mold and then laid onto the mold surface; this is referred to as wet lay-up.

False, Wet lay-up refers to the conventional hand lay-up process of impregnating the fiber layers with liquid uncured resin using a manual rolling technique

Like other types of rubber, thermoplastic elastomers must be vulcanized.

False, one of the advantages of thermoplastic elastomers is that they do not require vulcanization.

Extrusion of rubber is similar to extrusion of thermoplastics except that the length-to-diameter ratio of the extruder barrel is greater to avoid premature curing.

False, the length-to-diameter ratio of the extruder barrel must be less than in extrusion of thermoplastics to avoid premature curing.

Although thermoplastic fiber-reinforced plastics can be injection molded, thermosetting FRPs cannot be injection molded because of the risk of premature cross-linking in the injection chamber.

False,Thermosetting FRPs can be injection molded but control of the process is trickier because of the risk of premature cross-linking in the injection chamber

Relative to the hand lay-up method, moldings produced by the spray-up method, why?

Not as strong, fibers are continuous and directed in the hand lay-up method, whereas they are chopped and randomly oriented in the spray-up method

In rubber processing, the term compounding refers to?

adding vulcanizing agents

An apparatus that provides control over both temperature and pressure and is used to cure polymer matrix composites is called?

autoclave

Dip casting can be used to produce two of the following products?

ballons and rubber gloves

The most important rubber product is?

pneumatic tires

The chemical name of the ingredient recovered from the latex of the rubber tree is?

polyisoprene

The term prepreg stands for?

pre-impregnated fibers