Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MET 144 Materials and Processes II > Exam 2 Material > Flashcards

Exam 2 Material Flashcards

1
Q

Process where you heat a sheet of plastic, then form to a mold using a vacuum

A

Thermoforming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Advantages of Thermoforming (7 things)

A

very low tooling cost
low mold cost
low pressure req.
large parts easily formed
fast mold cycles
extremely adaptive to customer design needs
paint-able and colored plastic available

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Disadvantages of Thermoforming (6 things)

A

high cost of raw mats
high scrap
unable to mold parts with negative draft (concave)
limited part shapes
inherent wall thickness variation
internal stresses common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what materials can be used for thermoforming molds?

A

Cast or machined aluminum
wood
epoxy
steel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Areal Draw Ratio formula

A

Surface Area of part being formed
/
area of sheet needed to make part

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Area Ratio formula

A

area of sheet used to make part before forming
/
area of sheet used to make part after forming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

estimated initial sheet thickness (gauge) formula

A

(areal draw ratio) * (final thickness)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Pre-stretching tool used to improve dimensional consistency when the draw ratio is sufficiently large. It’s like a plunger that presses the material into the mold prior to vacuuming.

A

Plug Assists

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

in thermoforming, how do you determine the width or length of a part?

A

the larger dimension is considered the length, the smaller is considered the width

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the major differences between skin packs and blister packs?

A

Skin pack has plastic vacuum formed to the product, custom
Blister pack plastic is pre-formed prior to use with product, generic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

this process is used to shape thermoplastic sheets and films into discrete parts

A

Thermoforming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

this process is different from extrusion and injection molding because the material is not melted and higher pressures are not required.

A

Thermoforming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the principal steps to Rotational Molding?

A
  1. loading/charging
  2. heating (under rotation)
  3. cooling
  4. unloading/demolding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What’s the typical rotation ratio between axes in Rotational Molding?

A

3.75:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What constraints exist to get even coating in Rotational Molding?

A

Rotate about 2 axes simultaneously
different rotation speeds (major axis > minor axis)
Ratio of rotations not a whole number
Slow rotation (< 60 RPM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which process is capable of molding much larger parts than the other common thermoplastics processes?

A

Rotational Molding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

For which Thermoplastic process does the cost-effectiveness of the part increase with the size of the part?

A

Rotational Molding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are some common thermoset processes?

A

Reaction injection molding
extrusion
spin casting
foam molding
compression molding
transfer molding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What’s the primary/most-common process for thermosetting plastics?

A

Compression Molding

20
Q

What process preheats a preformed “pill”, then uses a plunger to force the preform into sprue, runners, and mold cavity?

A

Transfer Molding

21
Q

Which process mixes two liquids, as they are injected into a mold at high speed?

A

Reaction Injection Molding (RIM)

22
Q

What’s a downside of Reaction Injection Molding?

A

Controlling metering, mixing, temperature, and pressure are generally complex and expensive

23
Q

Which process rotates a disk-shaped mold about it’s centroidal axis, then pours in material, in order to force the material throughout the mold?

A

Spin Casting (Also called Centrifugal Rubber Mold Casting)

24
Q

What are the variables to consider with compression molding?

A

Material/Resin amount
Energy needed to heat material
Mold/material heating time
Compression force for that material
Cooling time/technique

25
Q

What are the three most-common types of composites?

A

Particulate
Laminar
Fiber-Reinforced

26
Q

Process requiring no special equipment

A

Particulate

27
Q

Which process pulls a fiber through a resin and forms the composite through a mold?

A

Pultrusion

28
Q

Process by which fibers are drawn through a resin bath, then immediately wrapped around a form to create the external shape of the mold.

A

Filament winding

29
Q

Which composite process impregnates fiber or fiber-sheet with resin, layers them on top of one another, heats it, then removes the surrounding air to compress the layers, bonding them together?

A

Vacuum bag method (VARTM)

30
Q

What are the main three variables in any thermoset- or thermoplastic-based composite processes?

A

Heat
Pressure
Time

31
Q

What are the objectives of Manufacturing Operations? (3)

A

Produce parts that adequately perform their intended task
Manufacture from a selected material with the desired shape, precision, and properties
Optimize parts for their service environment

32
Q

What are the three primary stages of Part Definition? (Design process)

A

Conceptual Stage - what does it need to do?
Functional Stage - What will the product look like and how will it behave?
Production Stage - How can the product be made profitably?

33
Q

What are the procedures for product realization?

A

Design
Materials Selection
Process Selection
Production
Evaluation
Redesign or modification

34
Q

What are the three main material properties, in the context of manufacturing? (General)

A

Mechanical
Physical
Environmental

35
Q

What are the types of joining?

A

Mechanical
Chemical
Metallurgical

36
Q

What plastic is most well-suited to welding?

A

Thermoplastic

37
Q

What are the types of plastic welding?

A

Ultrasonic
Laser
Linear Friction
Hotplate, Hot gas, Extrusion, Implant, Microwave

38
Q

Definition: Non-metallic material that fills the space between two surfaces to create a single joint.

A

Adhesive

39
Q

OSHA is a part of which government agency?

A

US Department of Labor

40
Q

What is an MSDS?

A

A Material Safety Data Sheet contains properties and safety information regarding a particular material.

41
Q

What is the CAS and what do they do?

A

Chemical Abstracts Service. This service registers chemicals/materials and assigns them numeric values for indexing and identification in a database of all chemicals.

42
Q

What are the types of hazards identified by the Hazard Communication Standard?

A

Chemical
Environmental
[War?]
Health hazards
Physical hazards

43
Q

“Green Manufacturing” is aimed at this

A

Reducing the energy and material intensiveness of manufacturing processes

44
Q

This refers to the amount of re-used material vs virgin material in a newly-formed plastic

A

Regrind Ratio

45
Q

Regrind ratio (formula)

A

mass of reground-material/mass of virgin material

MET 144 Materials and Processes II (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions