MMET 281 EXAM QUESTIONS WITH
100% CORRECT ANSWERS
An electrical means of removing metal by electrical erosion is called _____. - Answer-
Electrical discharge machining
In _____, the sprues and runners are kept hot by means of heating elements built into
the mold. - Answer- Hot runner molding
The extruder screw moves the plastic materials through the _____ of the machine. -
Answer- Barrel
Name two methods used to make films by the extrusion process. - Answer- Film
extrusion, blown film extrusion
The two basic blow-molding methods are _____ blowing and _____ blowing. - Answer-
Injection, extrusion
Static charges may be dissipated by the addition of _____ agents. - Answer- Antistatic
Polyvinyl chloride commonly has plasticizer added to provide ______. - Answer-
Flexibility
Polymerization is initiated by the use of _____. - Answer- Catalysts
Chemical _____ are sometimes used to produce cellular plastics. - Answer- Blowing
agents
Identify the special stabilizers that retard or inhibit degradation through oxidation. -
Answer- Antioxidants
To lower viscosity and aid in processing, _____ and _____ are added to resins. -
Answer- Lubricants and plasticizers
The _____ is the point of entry into the mold cavity. - Answer- Gate
Narrow channels that convey the molten plastics from the sprue to each cavity are
called _____. - Answer- Runners
Closely related to shrinkage is dimensional _____. - Answer- Tolerances
, The tapered channel connecting the nozzle and runners is called _____. - Answer-
Sprue
The most meaningful comparison in estimating the cost of a plastic product is cost per
_____. - Answer- Cubic centimeter
If wall thickness is not _____, the molded part may distort, warp, or have internal
stresses. - Answer- Uniform
The mark on a molded piece resulting from the meeting of two or more flow fronts
during the molding operation is called _____. - Answer- Flow line
Name four pieces of auxiliary equipment that may be required for injection-molding
operations. - Answer- Hopper dryer, loader, granulator, cooling tower
Three types of intermolecular forces found in plastics are? - Answer- Van der Waal's,
dipole interactions, and hydrogen bonds
The term used to describe the tying of adjacent polymer chains is? - Answer-
Crosslinking
The hydrocarbon molecule that contains double bonds is called? - Answer- Unsaturated
If a material is transparent, is it crystalline? - Answer- Generally, transparent plastics are
amorphous
To choose a tougher plastic choose one having a _____ area under the stress-strain
curve. - Answer- Larger
A plastic hinge relies on which property? - Answer- Fatigue resistance
As the melt-index value of a plastic goes up, the viscosity goes _____. - Answer- Down
Fillers used to make plastics conduct electricity are _____ and _____. - Answer- Metals,
graphite
The hollow plastic tubes used in blow molding is called a _____. - Answer- Parison
Name three extrusion-spinning processes. - Answer- Melt spinning, solvent spinning,
and wet spinning
Liquids that have a flash point below 38 degrees Celsius are called _____. - Answer-
Flammable
100% CORRECT ANSWERS
An electrical means of removing metal by electrical erosion is called _____. - Answer-
Electrical discharge machining
In _____, the sprues and runners are kept hot by means of heating elements built into
the mold. - Answer- Hot runner molding
The extruder screw moves the plastic materials through the _____ of the machine. -
Answer- Barrel
Name two methods used to make films by the extrusion process. - Answer- Film
extrusion, blown film extrusion
The two basic blow-molding methods are _____ blowing and _____ blowing. - Answer-
Injection, extrusion
Static charges may be dissipated by the addition of _____ agents. - Answer- Antistatic
Polyvinyl chloride commonly has plasticizer added to provide ______. - Answer-
Flexibility
Polymerization is initiated by the use of _____. - Answer- Catalysts
Chemical _____ are sometimes used to produce cellular plastics. - Answer- Blowing
agents
Identify the special stabilizers that retard or inhibit degradation through oxidation. -
Answer- Antioxidants
To lower viscosity and aid in processing, _____ and _____ are added to resins. -
Answer- Lubricants and plasticizers
The _____ is the point of entry into the mold cavity. - Answer- Gate
Narrow channels that convey the molten plastics from the sprue to each cavity are
called _____. - Answer- Runners
Closely related to shrinkage is dimensional _____. - Answer- Tolerances
, The tapered channel connecting the nozzle and runners is called _____. - Answer-
Sprue
The most meaningful comparison in estimating the cost of a plastic product is cost per
_____. - Answer- Cubic centimeter
If wall thickness is not _____, the molded part may distort, warp, or have internal
stresses. - Answer- Uniform
The mark on a molded piece resulting from the meeting of two or more flow fronts
during the molding operation is called _____. - Answer- Flow line
Name four pieces of auxiliary equipment that may be required for injection-molding
operations. - Answer- Hopper dryer, loader, granulator, cooling tower
Three types of intermolecular forces found in plastics are? - Answer- Van der Waal's,
dipole interactions, and hydrogen bonds
The term used to describe the tying of adjacent polymer chains is? - Answer-
Crosslinking
The hydrocarbon molecule that contains double bonds is called? - Answer- Unsaturated
If a material is transparent, is it crystalline? - Answer- Generally, transparent plastics are
amorphous
To choose a tougher plastic choose one having a _____ area under the stress-strain
curve. - Answer- Larger
A plastic hinge relies on which property? - Answer- Fatigue resistance
As the melt-index value of a plastic goes up, the viscosity goes _____. - Answer- Down
Fillers used to make plastics conduct electricity are _____ and _____. - Answer- Metals,
graphite
The hollow plastic tubes used in blow molding is called a _____. - Answer- Parison
Name three extrusion-spinning processes. - Answer- Melt spinning, solvent spinning,
and wet spinning
Liquids that have a flash point below 38 degrees Celsius are called _____. - Answer-
Flammable
