Coating Categories and Injection Molding Process

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What type of extruded product is produced using a die configuration for shaping hollow sections?

Sheet and film

Tubes and pipes (correct)

Solid profiles

Wire and cable coating

What is the cause of 'melt fracture' in extrusion, as described in the text?

Friction with the die

Die swell

Turbulent flow through the die entrance (correct)

Sharkskin

What type of extruded product is produced using a slit-die in the extrusion process?

Wire and cable coating

Sheet and film (correct)

Tubes and pipes

Filaments

What is the purpose of a chill-roll in extrusion for sheet and film production?

To cool and solidify the extrudate Signup and view all the answers

What are the characteristic properties of a foamed polymer mentioned in the text?

Low density and high strength per unit weight Signup and view all the answers

Which type of polymer foam has a matrix polymer that is a rubber?

Elastomeric foam Signup and view all the answers

What are some common gases used in polymer foams?

Air, nitrogen, and carbon dioxide Signup and view all the answers

How is mixing a physical blowing agent with the polymer different from mixing a liquid resin with air?

The physical blowing agent dissolves in the polymer melt under pressure Signup and view all the answers

What is the function of die swell in polymer melts?

To increase viscosity Signup and view all the answers

Which process involves the shape of the die orifice determining the cross-sectional shape of the extrudate?

Extrusion Signup and view all the answers

In extrusion, what does the typical pressure gradient in an extruder represent?

Approximation line for computations Signup and view all the answers

What is the primary function of an extruder screw inside the barrel?

Mix and transport polymer melt Signup and view all the answers

At what shear rate is viscosity typically evaluated for selected polymers?

$10^3$ s$^{-1}$ Signup and view all the answers

Which shaping process is associated with blow molding and rotational molding?

Thermoforming Signup and view all the answers

Which process involves inflating a soft polymer to conform to a blow mold?

Stretch blow molding Signup and view all the answers

In thermoforming, what happens to the plastic sheet placed over a concave mold cavity?

It is vacuum drawn into the cavity Signup and view all the answers

Which type of injection molding machine uses a plunger type alternative to the reciprocating screw?

Screw preplasticizer plunger type Signup and view all the answers

What is the purpose of the blow pin in blow molding?

Inflating the parison Signup and view all the answers

Which coating category involves coating an entire object by dipping or spraying?

Contour coating Signup and view all the answers

What is the main difference between vacuum thermoforming and pressure thermoforming?

Use of vacuum Signup and view all the answers

Which injection molding process involves injecting a preform molded around a blowing rod?

Injection blow molding Signup and view all the answers

What does compression transfer molding entail?

Charging the pot with softened polymer and pressing it into a mold cavity. Signup and view all the answers

Which material gives a porous or cellular structure to the polymer foam?

Polymer and gas mixture. Signup and view all the answers