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How Plastics are Made

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The IAPD Plastics Primer, Module 1. The International Association ... Plastics Fabrication. CNC machining centers. CNC lathes. Cutting and drilling. Profiling ... – PowerPoint PPT presentation

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Title: How Plastics are Made


1
  • How Plastics are Made
  • Understanding the Physical
  • Properties of Plastics

Prepared by the IAPD Education Committee (Module
1) Presented courtesy of Modern Plastics, Inc.
2
Processing
  • Hand (or spray) lay up
  • Laminating
  • Filament winding
  • Polymer orientation
  • Injection molding
  • Extrusion
  • Ram extrusion
  • Screw extrusion
  • Coextrusion
  • Casting
  • Compression molding
  • Rotational molding
  • Transfer molding
  • Calendering

3
Injection Molding
4
Extrusion
  • Ram
  • Screw
  • Coextrusion

5
Casting
Base Material
Reactive Additive
Oven
Casting
Mold
6
Compression Molding
  • Sheet and block molding
  • Parts molding

7
Rotational Molding
  • Low cost
  • Low pressure
  • Used in many markets
  • Easily adapted for short production runs

8
Transfer Molding
  • Widely used in the semiconductor industry

9
Calendering
10
Hand (or Spray) Lay Up
  • Used to make large parts
  • Used to produce fiberglass boats and camper
    shells

11
Laminating
Resin Binder
Reinforcing Substrate
Heat and pressure applied to the top and bottom
of the material
12
Filament Winding
  • Used to make containers and tubes
  • Items used for transportation of liquids or
    gasses

13
Polymer Orientation
  • Used to manufacture polymer fibers, strapping,
    webbing, film, sheet and profiles

14
Plastics Fabrication
  • CNC machining centers
  • CNC lathes
  • Cutting and drilling
  • Profiling
  • Routing and milling
  • Thermoforming
  • Forging
  • Milling
  • Welding
  • Bending
  • Bonding

15
Thermoforming
  • Single station thermoforming
  • Rotary station thermoformers
  • Pressure forming
  • Twin sheet thermoforming

16
Welding
  • Extrusion welding
  • Hot gas welding
  • Butt welding
  • Spin welding
  • Solvent welding

17
Bonding
  • The union of materials by adhesives to unite
    materials by means of an adhesive

18
The Performance of a Plastic Part is Affected By
  • Type of load
  • Size and application of load
  • Frequency of application of load
  • Speed of load
  • Temperature the part will see, and for how long
  • Use and environment of load

19
Mechanical Properties
  • Tensile strength
  • Elongation
  • Compressive strength
  • Creep
  • Shear strength
  • Flexural strength
  • Torsional strength
  • Modulus
  • Impact strength
  • Specific gravity
  • Water absorbtion
  • Coefficient of Friction (COF)

20
Testing Organizations
  • AFNOR - Association Francaise de Normalisation
    (France)
  • BSI - British Standards Institution (UK)
  • IEC - International Electrotechnical Commission
  • JIS - Japanese Industrial Standards

21
Tensile Strength
22
Elongation
23
Compressive Strength
  • Measured in pounds per square inch (PSI)
  • Higher PSI harder to compress

24
Creep
  • Associated with compressive strength
  • Creep at room temperature is called cold flow

25
Shear Strength
26
Flexural Strength
27
Torsional Strength

28
Modulus
  • Also referred to as stiffness
  • Used in conjunction with strengths (flexural
    modulus, tensile modulus, etc.)
  • Higher modulus stiffer material
  • Measured in PSI

29
Impact Strength
30
Specific Gravity
  • Related to the density of material
  • Can be used to determine the weight of material
  • Specific gravity of less than 1.0 will float in
    water

31
Water Absorption
  • Measured by the percentage of swell
  • Think of a sponge as having high percentage
    absorption

32
Coefficient of Friction (COF)
  • Resistance to sliding (slickness)
  • Low COF more slippery (think of wet ice as
    having lowest COF)
  • Static COF refers to initial movement from rest
  • Dynamic COF refers to being already in motion

33
Thermal Properties
  • Coefficient of thermal expansion
  • Heat deflection temperature
  • Continuous service temperature
  • Melting point
  • Thermal conductivity

34
Coefficient of Thermal Expansion (CTE)
  • Change in size as temperature changes
  • Lower value less change with temperature

35
Heat Deflection Temperature (HDT)
  • Temperature up to which a material can perform,
    under load, without distorting
  • Measured in degrees Fahrenheit, usually under 264
    PSI
  • Used most widely to predict performance

36
Continuous Service Temperature (CST)
  • Highest temperature a material can withstand and
    still retain at least 50 of its properties
  • Measured in degrees Fahrenheit, in air
  • In high temperatures, both CST and HDT must be
    considered

37
Melting Point
  • Temperature at which a crystalline thermoplastic
  • changes from solid to liquid

38
Thermal Conductivity
  • How much heat a material will conduct
  • Most plastics are good insulators (do not
    conduct heat well)
  • Higher value more heat conducted
  • Thermal conductivity of plastics is 300 to 2,500
    times less than most metals

39
Electrical Properties
  • Volume resistivity
  • Surface resistivity
  • Dielectric constant
  • Dielectric strength
  • Dissipation factor
  • Arc resistance
  • Flammability

40
Volume Resistivity
  • Ability of electricity to flow through a material
  • Measured in ohms/cm
  • Lower value more easily current flows
  • Higher value better resistor or insulator

41
Surface Resistivity
  • Ability of electricity to flow over the surface
    of a material
  • Same measurements as volume resistivity
  • Used to evaluate material when static discharge
    characteristics are critical

42
Surface Resistivity
Insulative Range
Conductive Range
Static Dissipative Range
20
9
10
11
12
1
2
3
4
5
1 10 10 10 10 10
10 10 10 10 10
Shielding Range
6
7
8
10 10 10
106 to 108 Critical Range for ESD Control
43
Dielectric Constant
  • That property of a dielectric that determines the
    electrostatic energy stored per unit volume for
    unit potential gradient

44
Dielectric Strength
  • Effectiveness of material as an insulator
  • Measured in volts/.001 thickness
  • Higher value better insulator
  • Voltage is increased until material arcs, showing
    a breakdown

45
Dissipation Factor
  • Tangent of the loss angle of the insulating
    material

46
Arc Resistance
  • Time required for an arc to establish a
    conductive path on the surface of an organic
    material

47
Flammability
  • Measured by UL94 ratings
  • Most favorable ratings are given to materials
    that extinguish themselves rapidly, and do not
    drip flaming particles
  • Scale from highest burn rate gt most flame
    retardant is HB, V-2, V-1, V-0, 5V

48
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