Product Guide

Automotive / Electrical / Electronics

Bakelite® Engineering Thermosets

Bakelite® engineering thermosets

from Hexion Inc. (Hexion) are high-

performance molding compound

products designed for automatic

injection or compression molding

processing. These materials,

which contain curable synthetic

resins, fillers, and additives such as

hardeners, inhibitors and coloring

agents, satisfy the most demanding

applications.

A Superior Option

Bakelite® engineering thermosets’ excellent long-term mechanical behavior, good chemical resistance to automotive media, thermal stability and superior electrical properties make them excellent alternatives to light-metal alloys and standard engineering thermoplastics.

Applications■■ Automotive under-the-hood■■ Electrical■■ Electronics

This following pages contain a wealth of information on the handling, properties, processing and finishing of Bakelite® products.

Key Benefits■■ Weight savings■■ Cost reduction■■ Design flexibility■■ Function integration ■■ Electrical insulation

2

Product Guide Bakelite® Engineering Thermosets

1. Product Overview, Quality Management, Delivery, Handling and Storage 3

2. Properties: Chemical, Mechanical and Electrical 5

3. Processing: Molding, Deflashing and Post Curing 14

4. Finishing 18

5. Use of Recycled Material 19

6. Technical Service – Engineering 19

3

Product Overview Product Characteristics Application Areas

Bakelite® PF 1110 High mechanical strength, dimensionally accurate, isotropic, heat stable, glass fiber reinforced, 80% inorganically filled phenolic molding compound.

High precision, mechanically strong motor vehicle engine attachments, pump parts, pulleys and brake pistons.

Bakelite® PF 2874 Highly temperature-stable, electrically insulating, UL listed 0.75 mm/V-0 (BK), dimensionally accurate, glass fiber reinforced, inorganically filled phenolic molding compound.

General purpose parts with high demands on thermal stability, such as carbon brush holders, end plates for electrical motors, insulating flanges, clamp boards, bobbins, cross bars, terminal boards, switches/regulator knobs etc.

Bakelite® UP 3415 High mechanical strength, dimensionally accurate, flame-retardant, UL listed, styrene free, glass fiber reinforced, inorganically filled unsaturated polyester molding compound.

Safety switch houses and electro-technical parts, e.g. control devices, lamp housings, clamp boards, bobbins etc.

Bakelite® PF 6501 High mechanical strength, dimensionally accurate, automotive media resistant, heat stable, glass fiber reinforced, inorganically filled phenolic molding compound.

Dynamically and thermally highly stressed automotive parts, vacuum pump parts and pulleys.

Bakelite® PF 6510 Highly resistant to automotive media, dimensionally accurate, heat stable, glass fiber reinforced, inorganically filled phenolic molding compound.

Parts subject to chemicals and heat, mechanically stressed automotive pump parts like water pump housings.

Bakelite® PF 6680 Low abrasion, chemically resistant, low warpage, glass fiber reinforced and glass beadfilled phenolic molding compound.

Abrasion critical parts e.g. piston and guidance elements.

Bakelite® PF 6771 High mechanical strength, dimensionally accurate, automotive media resistant, heat stable, glass fiber reinforced phenolic molding compound.

Mechanically and thermally highly stressed automotive parts, secondary pistons in the master brake cylinder.

Bakelite® PF 7596 Chemically resistant to fuel and diesel, dimensionally accurate, heat conductive, glass fiber reinforced, graphite modified phenolic molding compound.

Fuel and diesel resistant automotive parts in which tribological properties are critical, such as fuel pump impellers and housings.

Bakelite® EP 8412 Highly electrical insulating, UL listed (RTI 155 °C), dimensionally accurate, chemical and heat resistant, glass fiber reinforced, inorganically filled epoxy molding compound.

Encapsulation of electric parts, e.g. electromagnetic coil.

Introduction

4

Quality Management / Standards

Delivery, Handling and Storage

Hexion has set up a quality management system consistent with DIN EN ISO 9001 and an environmental management system consistent with DIN EN ISO 14001. Conformity with the standards and effectiveness of the two management systems is certified and is under constant supervision by an external inspection organization.

The high and consistent quality of our products is periodically confirmed by independent test organizations such as BAM – Berlin, Germany; MPA – Darmstadt, Germany; UL – USA; and CSA – Canada. UL-listed molding compounds are monitored by European testing institutes appointed by Underwriters Laboratories Inc.

Form of Delivery

Bakelite® engineering thermosets are typically delivered in a low dust, free-flowing milled granular form which is easy to process automatically.

Packaging

Bakelite® engineering thermosets are supplied in 25 kg moisture barrier paper bags, and in 500 and 1000 kg anti-static bags (type D).

Shelf life

Cool and dry storage in the original sealed bags is necessary to prevent alteration of flow properties or processability. We advise storing the product in closed bags for one to two days in the processing space to ensure temperature equalization before use. With proper storage, the following shelf lives can be expected:

PF molding compounds Recommended storage conditions: 50 – 60 % relative humidity at approximately 20 °C Shelf life: 2 years

EP molding compounds Recommended storage conditions: 50 – 60 % relative humidity at a maximum of 20 °C Shelf life: 6 months.

Safe handling

Bakelite® engineering thermoset grades are not known to contain asbestos compounds, toxic heavy metals, halogen compounds, or solvents in any appreciable concentration. Nonetheless, care must be taken that production rooms are well-ventilated and processing machinery is properly exhausted, as ammonia is released during processing.

Nomenclature The four segments of our product keys provide the user with detailed information, as explained in the footnotes below.

Example:

PF 1 1110 3 2 9005 3 P 4

1 Resin System

PF phenolic formaldehyde resin

EP epoxy resin

UP unsaturated polyester resin

2 Grade / Type

The first digit indicates the main property of the special Bakelite® engineering thermoset, as follows:

1 Excellent shape stability under heat

2 Good shape stability under heat

3 Excellent electrical insulation unsaturated polyester grade

6 Good notched impact strength

7 Excellent tribological properties

8 Excellent electrical insulation

3 Shade

All Bakelite® engineering thermosets are black, designated by RAL code 9005.

4 Process

The letters indicate the process for which the given Bakelite® engineering thermoset has been adjusted:

S Injection molding

P Compression molding

5

This section describes the important characteristics of Bakelite® engineering thermosets as listed on our technical

datasheets. These properties have been ascertained according to standard test methods.

Table 1a: Properties of Bakelite® Engineering Thermosets

Product Norm Bakelite®

PF 1110Bakelite®

PF 2874Bakelite®

UP 3415Bakelite®

PF 6501Bakelite®

PF 6510

Reinforcement Glass Fiber & Mineral Dust

Glass Fiber & Mineral Dust

Glass Fiber & Mineral Dust

Glass Fiber

Glass Fiber & Beads

% GF40-MD40

GF15-MD20

GF 15-MD60

GF35-MD10

GF30-GB25

Physical Properties

Density (g/dm3) ISO 1183 2060 1570 2000 1600 1710

Water Absorption (%) ISO 62 0.1 0.55 0.3 0.25 0.2

Mechanical Properties

Tensile Strength (MPa) ISO 527 150 65 45 85 100

Tensile Modulus (MPa) 29000 10500 10000 15000 16500

Flexural Strength (MPa) ISO 178

260 125 105 180 200

Flexural Modulus (MPa) 27000 10500 13000 12500 15500

Charpy Impact Strength (kJ/m3)

ISO 179 15.5 9.0 8.5 12 15

Charpy Notched Impact Strength (kJ/m3)

4.5 2.0 4.5 3.5 4

Compression Strength (MPa)

ISO 604 325 225 160 285 175

Ball Identation Hardness (MPa)

ISO 2039-1

- 350 325 400 -

Poisson Ratio (-) - 0.25 - - 0.33 0.33

Thermal Properties

Heat Deflection under 8 MPa (°C)

ISO 75 190 150 210 170 175

Heat Deflection under 1.8 MPa (°C)

> 250 200 > 250 230 235

Dimensional Stability

Mold Shrinkage Longitudinal (%)

ISO 2577 0.15 0.5 0.3 0.2 0.15

Post Mold Shrinkage (%)

0.03 0.25 0.01 0.1 0.05

Coefficient Of Thermal Expansion:

-Parallel (/°C) EN 61009 0.1 0.32 - 0.35 0.25

-Perpendicular (/°C) 0.1 - - - 0.11

-Non Post-Cured (/°C) 0.1 - - - 0.25

Electrical Properties

Surface Resistivity (V) IEC 60093 1E+11 1E+11 1E+12 1E+10 1E+11

Volume Resistivity (V) IEC 60093 1E+12 1E+12 1E+13 1E+11 1E+12

Electric Strength (kV/mm)

IEC 60243-1

27 26 29 30 25

Proof Tracking Index (PTI)

IEC 60112 225 175 600 - -

Properties

6

Note: These values can be used to compare the properties of different materials, but they have limited applicability to finished parts. Properties of finished parts depend to a large extent upon design and

conditions of use. Measurements demonstrating a finished part’s chemical resistance and long term mechanical strength have been performed under application conditions.

Table 1b: Properties of Bakelite® Engineering Thermosets

Product Norm Bakelite®

PF 6680Bakelite®

PF 6771Bakelite®

PF 7596Bakelite®

EP 8412

Reinforcement Glass Fiber & Beads

Glass Fiber

Glass Fiber & Graphite

Glass Fiber & Mineral Dust

% GF30-GB20

GF50 GF10-MD15-CD40

GF40-MD30

Physical Properties

Density (g/dm3) ISO 1183 1700 1700 1630 1850

Water Absorption (%) ISO 62 0.10 0.2 0.08 0.15

Mechanical Properties

Tensile Strength (MPa) ISO 527 115 115 60 55

Tensile Modulus (MPa) 20000 17000 16000 13000

Flexural Strength (MPa) ISO 178 180 215 95 120

Flexural Modulus (MPa) 13500 16000 14000 15000

Charpy Impact Strength (kJ/m3)

ISO 179 15.0 17,5 4.75 8.5

Charpy Notched Impact Strength (kJ/m3)

3.5 4,5 - 3.8

Compression Strength (MPa)

ISO 604 275 250 130 170

Ball Identation Hardness (MPa)

ISO 2039-1

450 - - 400

Poisson Ratio (-) - - - - -

Thermal Properties

Heat Deflection under 8 MPa (°C)

ISO 75 170 170 175 120

Heat Deflection under 1.8 MPa (°C)

230 230 160

Dimensional Stability

Mold Shrinkage Longitudinal (%)

ISO 2577 0.25 0.2 0.3 0.3

Post Mold Shrinkage (%)

0.05 0.05 0.1 0.05

Coefficient Of Thermal Expansion:

-Parallel (/°C) EN 61009 0.26 0.25 0.23 0.23

-Perpendicular (/°C) - 0.25 - 0.23

-Non Post-Cured (/°C) - - - -

Electrical Properties

Surface Resistivity (V) IEC 60093 1E+12 1E+11 1E+11 -

Volume Resistivity (V) IEC 60093 1E+13 1E+12 1E+12 -

Electric Strength (kV/mm)

IEC 60243-1

30 30 - -

Proof Tracking Index (PTI)

IEC 60112 250 - - -

7

Chemical Resistance For automotive under the hood parts, chemical resistance to automotive fluids is crucial. To test our materials, conditions representative of typical end-uses were applied. Mechanical properties were then measured as a function of exposure time to long life coolant, hydraulic fluid, and fuel, at elevated temperatures. The graphs shown demonstrate the excellent chemical resistance of Bakelite® engineering thermoset grades PF 1110 and PF 6510—their mechanical strength is maintained at a high level. Also, the sample dimensions remain stable under the exposure conditions. Bakelite®

engineering thermosets do not need additional corrosion protection, whereas die-cast aluminum parts require post-treatment.

For water pump housing and impeller parts, the recommended Bakelite® engineering thermoset grade is PF 6510. Figure 1 demonstrates the flexural strength and modulus as a function of time, when stored in Glysantin® G30 coolant at an elevated temperature -120 °C In Figure 2, the relative dimen-sions and weight are shown under the same test conditions.

Flex

ural

Mod

ulus

[ G

Pa

]

Flexural Modulus

Flexural Strength 250.0

200.0

150.0

100.0

50.0

30.000

25.000

20.000

15.000

10.000

5.000

0.0000.0

0 3000

Time [ hours ]

Flex

ural

Str

engt

h [ M

Pa

]

Figure 1. Flexural Strength and Modulus of Bakelite® PF 6510 in Glysantin® G30 at 120 °C over 3000 hours (ISO 175)

Flex

ural

Mod

ulus

[ G

Pa

]

Flexural Modulus

Flexural Strength 250.0

200.0

150.0

100.0

50.0

30.000

25.000

20.000

15.000

10.000

5.000

0.0000.0

0 3000

Time [ hours ]

Flex

ural

Str

engt

h [ M

Pa

]

Figure 1. Flexural Strength and Modulus of Bakelite® PF 6510 in Glysantin® G30 at 120 °C over 3000 hours (ISO 175)

Width Thickness Mass

80%

85%

90%

95%

100%

105%

110%

3000 [ h ]

1500 [ h ]

0 [ h ]

Rel

ativ

e di

men

sion

s [ %

]

Figure 2. Dimensional Stability of Bakelite® PF 6510 in Glysantin® G30 at 120 °C over 3000 h. (ISO 175)

Width Thickness Mass

80%

85%

90%

95%

100%

105%

110%

3000 [ h ]

1500 [ h ]

0 [ h ]

Rel

ativ

e di

men

sion

s [ %

]

Figure 2. Dimensional Stability of Bakelite® PF 6510 in Glysantin® G30 at 120 °C over 3000 h. (ISO 175)

For master cylinder brake pistons and oil pump parts, the recommended Bakelite® engineering thermoset grades are PF 6510 and PF 1110, respectively. In Figure 3, the flexural strength and modulus are measured as a function

of time, with storage in ATE DOT 4 brake fluid, at an elevated temperature of 120 °C. In Figure 4, the relative dimensions and weight are shown under the same test conditions.

8

Flex

ural

Mod

ulus

[ G

Pa ]

Flexural ModulusPF 6510 [ GPa ]

Flexural ModulusPF 1110 [ GPa ]

Flexural StrengthPF 6510 [ MPa ]

Flexural StrengthPF 1110 [ MPa ]

400.0

250.0

300.0

350.0

200.0

150.0

100.0

50.0

35.000

30.000

25.000

20.000

15.000

10.000

5.000

0.0000.00 200

Time [ hours ]

Flex

ural

Stre

ngth

[ M

Pa ]

Figure 3. Flexural Strength and Modulus of Bakelite® PF 1110 and PF 6510 in ATE DOT 4 brake fluid at 120 °C (ISO 178)

Flex

ural

Mod

ulus

[ G

Pa ]

Flexural ModulusPF 6510 [ GPa ]

Flexural ModulusPF 1110 [ GPa ]

Flexural StrengthPF 6510 [ MPa ]

Flexural StrengthPF 1110 [ MPa ]

400.0

250.0

300.0

350.0

200.0

150.0

100.0

50.0

35.000

30.000

25.000

20.000

15.000

10.000

5.000

0.0000.00 200

Time [ hours ]

Flex

ural

Stre

ngth

[ M

Pa ]

Figure 3. Flexural Strength and Modulus of Bakelite® PF 1110 and PF 6510 in ATE DOT 4 brake fluid at 120 °C (ISO 178)

Width Thickness Mass90%

95%

100%

105%

110%

195 [ h ] PF 6510 195 [ h ] PF 1110 0 [ h ]

Rela

tive

dim

ensio

ns [

% ]

Figure 4. Dimensional Stability of Bakelite® PF 1110 and PF 6510 in ATE DOT 4 brake fluid at 120 °C

Width Thickness Mass90%

95%

100%

105%

110%

195 [ h ] PF 6510 195 [ h ] PF 1110 0 [ h ]

Rela

tive

dim

ensio

ns [

% ]

Figure 4. Dimensional Stability of Bakelite® PF 1110 and PF 6510 in ATE DOT 4 brake fluid at 120 °C

110%

90%

95%

100%

105%

Rela

tive

Dim

ensio

ns [

% ]

Width Thickness Volume

Figure 5. Dimensional stability of Bakelite® PF 1110 and PF 7596 in FAM-B fuel at 80 °C

250 [ h ] PF 1110

0 [ h ]

250 [ h ] PF 7596

110%

90%

95%

100%

105%

Rela

tive

Dim

ensio

ns [

% ]

Width Thickness Volume

Figure 5. Dimensional stability of Bakelite® PF 1110 and PF 7596 in FAM-B fuel at 80 °C

250 [ h ] PF 1110

0 [ h ]

250 [ h ] PF 7596

For fuel pump housings and impellers, the recommended Bakelite® engineering thermoset grades are PF 1110 and PF 7596, respectively.

In Figure 5, the relative dimensions are measured as a function of time, with storage in FAM-B test fuel, at an elevated temperature of 80 °C.

9

Mechanical Properties

Short Term Stress

PF 1110300

200

100

150

250

50

00 50 100 150 200

PF 2874UP 3415PF 6501

Temperature [ °C ]

Flex

ural

Stre

ngth

[ M

Pa ]

Figure 6a. Flexural Strength of Bakelite® Engineering Thermoset PF 1110,2874, 6501 and UP 3415 (ISO 178)

PF 1110300

200

100

150

250

50

00 50 100 150 200

PF 2874UP 3415PF 6501

Temperature [ °C ]

Flex

ural

Stre

ngth

[ M

Pa ]

Figure 6a. Flexural Strength of Bakelite® Engineering Thermoset PF 1110,2874, 6501 and UP 3415 (ISO 178)

PF 6510250

150

50

100

200

00 50 100 150 200

PF 6680PF 7596

Flex

ural

Stre

ngth

[ M

Pa ]

Temperature [ °C ]

Figure 6b. Flexural Strength of Bakelite® Engineering Thermoset PF 6510,6680 and 7596 (ISO 178)

PF 6510250

150

50

100

200

00 50 100 150 200

PF 6680PF 7596

Flex

ural

Stre

ngth

[ M

Pa ]

Temperature [ °C ]

Figure 6b. Flexural Strength of Bakelite® Engineering Thermoset PF 6510,6680 and 7596 (ISO 178)

The mechanical properties outlined in Table 1 may serve as initial input for strength calculations and the design of molded parts. Short and long-term tests carried out under a variety of conditions

provide the design engineer with a basis for calculation when designing components subject to temperature and prolonged stress forces.

In Figures 6 and 7, mechanical properties for post-cured material are shown as a function of temperature. Bakelite® Engineering thermosets maintain good mechanical properties up to 200 °C. Semi-crystal-line engineering thermoplastics show a deterioration in mechanical properties

when approaching the glass transition temperature, since the amorphous parts change from the glass to the rubbery state. Engineering thermoplastics also exhibit more swelling stress in response to internal friction than engineering thermosets do.

10

Long Term Stress Creep

30000

20000

10000

5000

15000

25000

0

0 50 100 150 200

Flex

ural

Mod

ulus

[ M

Pa

]

Temperature [ °C ]

PF 1110

PF 2874

UP 3415

PF 6501

Figure 7a. Flexural Modulus of Bakelite® PF 1110, 2874, 6501 and UP 3415 (ISO 178)

30000

20000

10000

5000

15000

25000

0

0 50 100 150 200

Flex

ural

Mod

ulus

[ M

Pa

]

Temperature [ °C ]

PF 1110

PF 2874

UP 3415

PF 6501

Figure 7a. Flexural Modulus of Bakelite® PF 1110, 2874, 6501 and UP 3415 (ISO 178)

20000

14000

12000

8000

6000

4000

2000

10000

18000

16000

0

0 50 100 150 200

Flex

ural

Mod

ulus

[ M

Pa

]

Temperature [ °C ]

PF 6510

PF 6680

PF 7596

Figure 7b. Flexural Modulus of Bakelite® PF 6510, 6680 and 7596 (ISO 178)

20000

14000

12000

8000

6000

4000

2000

10000

18000

16000

0

0 50 100 150 200

Flex

ural

Mod

ulus

[ M

Pa

]

Temperature [ °C ]

PF 6510

PF 6680

PF 7596

Figure 7b. Flexural Modulus of Bakelite® PF 6510, 6680 and 7596 (ISO 178)

56 MPa

84 MPa140 MPa1.0

0.8

0.6

0.4

0.20.1

0.5

0.7

0.9

0.3

0.00.1 1 10 100 1000

log10 time t [ hours ]

Cre

ep S

train

[ %

]

Figure 8. Creep Strain of Bakelite® PF 1110 at 120 °C over 1000 hours (ISO 899-1)

56 MPa

84 MPa140 MPa1.0

0.8

0.6

0.4

0.20.1

0.5

0.7

0.9

0.3

0.00.1 1 10 100 1000

log10 time t [ hours ]

Cre

ep S

train

[ %

]

Figure 8. Creep Strain of Bakelite® PF 1110 at 120 °C over 1000 hours (ISO 899-1)

Figures 8, 9 and 10 show the long-term creep behavior of Bakelite® thermoset grades PF 1110, PF 6510 and PF 6501 under two or three different tensile loads and at an elevated temperature of

120 °C. The tests were carried out to a time under load of 1000 hours. These materials are very stable at the lower load levels, as can be seen from the small spread on the graphs.

11

Fluctuating Stress Fatigue

1.4

1.2

0.6

0.2

0.4

1.0

0.8

00.1 1 10 100 1000

log10 time t [ hours ]

120 MPa72 MPa

Cre

ep S

train

[ % ]

Figure 9. Creep Strain of Bakelite® PF 6510 at 120 °C

41 MPa

61 MPa102 MPa1.0

0.8

0.6

0.4

0.20.1

0.5

0.7

0.9

0.3

0.00.1 1 10 100 1000

log10 time t [ hours ]

Cre

ep S

train

[ %

]

Figure 10. Creep Strain of Bakelite® PF 6501 at 120 °C over 1000 hours (ISO 899-1)

The excellent creep behavior of engineering thermosets permits direct fastening of assembly screws into threaded holes, and hence the number of required assembly steps and parts is minimized. Direct fastening can also be achieved by over-molding the metal bearings.

Creep test results provide the design engineer with a basis for calculation when designing components subject to prolonged stress loads.

Molded parts must maintain their mechanical properties throughout their service lives. They are often subject to long-term dynamic loads and as a result, fatigue strength is an important design driver for these components. Figures 11 and 12 show the Bakelite® engineering thermoset grades PF 1110 and PF 6510 compounds’ outstanding fatigue performance, with minimal strength degradation after millions of cycles. In comparison, metals degrade much more; strength reductions of

over 50% are typical for these materials after 1 million cycles. Parts made with Bakelite® engineering thermoset grades PF 1110 or PF 6510, however, typically only lose about 10-30% of their strength under the most demanding dynamic loads. Use of these light, yet durable materials helps to further reduce the weight of dynamically loaded parts and makes lifespan predictions much easier for the design engineer.

1.4

1.2

0.6

0.2

0.4

1.0

0.8

00.1 1 10 100 1000

log10 time t [ hours ]

120 MPa72 MPa

Cre

ep S

train

[ % ]

Figure 9. Creep Strain of Bakelite® PF 6510 at 120 °C

41 MPa

61 MPa102 MPa1.0

0.8

0.6

0.4

0.20.1

0.5

0.7

0.9

0.3

0.00.1 1 10 100 1000

log10 time t [ hours ]

Cre

ep S

train

[ %

]

Figure 10. Creep Strain of Bakelite® PF 6501 at 120 °C over 1000 hours (ISO 899-1)

12

100.00

10.001.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07

Load Cycles N [ log ] [ - ]

Stre

ss A

mpl

itude

s

Stre

ss c

ycle

freq

uenc

y 5

Hz,

R =

0.1

a [ lo

g ] [

MPa

]

Figure 11. Fatigue Strength of Bakelite® PF 1110 (Wöhler Curve) (ISO 527-2)

100.00

10.001.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07

Load Cycles N [ log ] [ - ]

Stre

ss A

mpl

itude

s

Stre

ss c

ycle

freq

uenc

y 5

Hz,

R =

0.1

a [ lo

g ] [

MPa

]

Figure 12. Fatigue Strength of Bakelite® PF 6510 (Wöhler Curve) (ISO 527-2)

Electrical Properties Thanks to their impressive range of properties, Bakelite® engineering thermosets are highly valued for electrical engineering and electronics applications. These materials are well

suited for the manufacture of electrically demanding moldings that combine outstanding resistance to thermal stress with good mechanical strength.

Automotive Specifications Bakelite® engineering thermosets are specified by leading automotive manufacturers and their suppliers,

including BMW, Audi, VW and Daimler. Some grades are also listed by the Bosch Group and Ixetic.

13

Campus Leading plastics manufacturers have developed the CAMPUS (Computer Aided Material Preselection by Uniform Standards) joint materials database. It allows consumers, engineers and processors to choose materials rapidly

and objectively. Bakelite® engineering thermoset grades are listed in the CAMPUS database and can be found through the website: www.campusplastics.com

Table 2: UL Test Results For Bakelite® Phenolic Engineering Thermosets.

Material Color Minimum thickness (mm)

Flame Class

UL 94

HWI

Hot Wire Ignition

UL 746A

HAI

High Current Arc Ignition

UL 746A

RTI

Relative Temperature Index

UL 746B

HVTR

High Voltage Arc Tracking UL 746A

TAR

Time of Arc Resis-tance

D 495

CTI

Compa-rative Tracking Index

IEC 112

Elec. Mech.

With Impact

Without Impact

UP 3415 ALL 0.75 V-0 1 2 170 130 130 0 4 0

ALL 1.5 V-0 0 1 170 130 130

ALL 3.0 V-0 0 1 170 130 130

EP 8412 BK 1.5 HB 1 3 155 155 155 0 4 2

BK 2.0 HB 0 1 155 155 155

PF 2874 BK 0.75 V-0 0 0 150 150 150 0 5 3

BK 1.5 V-0 0 0 150 150 150

BK 3.0 V-0 0 0 150 150 150

Fire Prevention and Safety Every year, fires inflict serious injury and result in significant property and environmental damage. Bakelite® phenolic engineering thermosets comply with the strictest fire protection regulations set for public transportation. These materials are intrinsically fire resistant, while our epoxy and polyester engineering thermosets contain halogen-free flame-retardant systems to enhance their fire resistance. All of these products retain dimensional stability when subjected to peak service temperatures for a short period of time, and offer a considerable safety margin. The combination of excellent electrical insulating properties and high heat resistance makes them an outstanding

choice for electrical engineering / electronics applications. Examples of conductive devices requiring insulation are: controls, housings, switch gears, entertainment electronics, communications technology and lighting.

Bakelite® phenolic engineering thermosets also meet public transport regulations with respect to smoke density and composition, passing the UL 94 fire resistance test with a V-0 rating, without halogen flame retardants. These plastics’ basic flame retardant and electrical properties are documented on Underwriters Laboratories’ yellow cards.

14

Injection Molding Injection molding is a versatile and economically efficient process for producing complex composite parts. Injection molding of thermosets is comparable to that of thermoplastics. A homogeneous melt is prepared within a plasticizing cylinder. The powder or granulated thermoset material is dosed by a rotating screw while being plasticized through friction and heat transfer from the cylinder wall. After dosing, the rotation of the screw is stopped and the screw is used as a ram. The melt is injected into the mold

through the machine nozzle. Injection and holding pressures are controlled to prevent back flow and to ensure optimal conditions in the mold.

When the cure is completed, the mold is opened and the part removed. Cycle times in the range of 5-20 seconds per mm part thickness can be achieved with Bakelite® engineering thermoset products.

Several critical aspects of the injection molding process are reviewed in more detail in the following sections.

The screw homogenizes the molding compound and is controlled by speed and back pressure. The back pressure counteracts the screw return movement and further compresses the granules. The recommended back pressure is 0.5 – 2 MPa.

Temperature has a large impact on mold processing and part quality. The barrel temperature should be in the range of 60 – 75 °C in the feed zone and 80 – 100 °C in the machine nozzle zone. These temperatures can be achieved with either a water or oil heating system. This low temperature requirement is an

advantage of thermosets compared with thermoplastics, which take much more energy to melt and plasticize.

The barrel-nozzle temperature difference is amplified by the variation in frictional heat. The melt at the machine nozzle absorbs a large amount of frictional heat while the melt near the feed zone is hardly sheared at all. Because of this large molding compound temperature gradient, the back pressure should be graduated from the feed zone to the machine nozzle.

Plasticizing

Figure 8. Plasticizing the molding compound

Molding

Figure 9. Injection into the mold.

Molding Bakelite® engineering thermoset grades are processed into molded parts through the influence of pressure and temperature. Standard processing

methods such as injection and compression molding can be applied, as well as a number of hybrid variants.

Processing

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The injection rate determines how fast the melt flows into the mold, and is of great significance for virtually all quality criteria in thermoset processing. Internal pressure during the compression phase should be > 15 MPa. After cavity filling, the system switches to holding pressure, which is typically set at around 60% of the injection pressure, to avoid shrink marks and deformation. During the injection molding process the mold wall should be kept isothermally in the range of 160 – 190 °C.

During molding, the melt temperature profile is influenced by heat conduction from the mold and by the exothermal

reaction heat. After injection, the melt temperature rises beyond that of the mold wall because of the exothermal reaction taking place. As the curing process progresses, the melt temperature returns to the set mold wall temperature.

When about 70% of the conversion is achieved the part typically will be sufficiently stable for demolding. To ensure optimal cycle time, the mold wall temperature should be set within the upper limit range 160 – 190 °C.

Internal pressure measurements are used to follow the melt flow behavior and to control finished part quality and cycle time. The graph in Figure 13

shows the evolution of the hydraulic pressure and the internal pressure during the filling and holding phases.

0 – 1: hydraulic pressure increases sharply due to melt compression.

1 – 2: Melt leaves the machine nozzle and flows into the sprue, where the larger cross-section results in decompression.

2 – 3: Flow resistances during cavity filling lead to hydraulic pressure increases.

3 – 4: The machine switches from injection to holding pressure, and hydraulic pressure drops slightly.

4 – 5: The machine sets up holding pressure.

5 – 7: When the holding pressure is turned off, the machine switches back to metering.

Internal Pressure Control

Mould Filling Curing Phases

1

0

23

4

5

6 7

Time [ sec ]

Hydraulic Pressure [ bar ] Internal Pressure [ bar ]

Figure 13. Hydraulic and Internal Pressure Changes during Filling and Holding

Mould Filling Curing Phases

1

0

23

4

5

6 7

Time [ sec ]

Hydraulic Pressure [ bar ] Internal Pressure [ bar ]

Figure 13. Hydraulic and Internal Pressure Changes during Filling and Holding

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For experimental molds or parts with limited production numbers, steel with a surface hardness < 56 HRc or aluminum is sufficient. For series production with high volumes, steel with a chrome content > 11% is necessary. Good results have been achieved using steel qualities of 1.2379 and 1.2080. These steels prolong the lifespan of the

cavities, help maintain tight tolerances, and inhibit material from sticking to the tool. The surface of lower hardness or lower chrome-content steels can be improved by the usual plating methods. Nickel, Chrome or Chrome-Nitride plating is recommended.

Special commercial modeling programs are available to design tools and calculate temperature profiles to determine the preferred positioning of the heating patrons. The filling of the mold, the pressure build-up and

conversion rate can also be simulated using these programs. When a very tight dimensional accuracy is required with low warpage of the part, the tool needs to exhibit a temperature accuracy of ±2.5 °C.

Sprues can be divided into three sub-groups based upon their shapes and positions:■■ Sprues originating from direct, film, cone, ring or disc gates. These stay with the molded part and require extra processing to be separated.

■■ Sprues with submarine or “tear off” pin gates. These are separated from the molded part and ejected automatically.

■■ Sprues with straight tab gates. These are separated from the molded part while still in the tool.

Direct sprues are very commonly used, as are ring sprues for ring-shaped single-cavity concentric moldings of medium or small internal diameter. Sprues and runners should taper 2 to 3°. A sprue diameter of 4 - 8 mm is typical. The sprue bushings, runners and gate channels should be polished. Gates should be as large as possible to minimize wear and to maintain fiber length. Undercuts should be avoided.

A hot or cold runner, as is usually used for thermoplastics, is not feasible because these materials are too viscous.

Tool Material

Tool Design

Runner System

Figure 11. Structure of a runner system.

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The Bakelite® engineering thermoset grade is fed volumetrically or by weight into the heated mold. The mold is closed, and the material softens and fills it. The molded part can be removed after a curing period determined by the material’s reactivity, its prior treat-ment, the mold temperature, and the mold’s wall thickness. Recommended settings are, a mold temperature of 160 – 190 °C, and cavity molding pressure > 15 MPa. Compression molding may be a manual, semiautomatic or fully automatic process. Among the various types of compression molds, semi-

positive molds have proven especially successful since they compress the molding compounds optimally, enabling even dimensions that are not mold specific to be produced more reliably.

The major advantages of compression molding are: greatly diminished processing and post shrinkage, far less warpage, and far less damage of reinforcing fillers. The disadvantage is that cycle times vary according to maximum wall thickness, on the order of 20 – 40 seconds per mm.

Injection compression molding is a variation of the standard injection molding process. The melt is injected into a partially closed mold. Cavity filling is completed by the final mold closure. This process requires especially precise machine controls and special mold designs (semi-positive molds).

Technically, transfer molding is a hybrid of compression and injection molding. The pelletized and preheated or preplasticized melt is pushed by a plunger from an antechamber into the mold. Three-plate molds with plungers working from the top can be built into conventional presses. Single split molds, easier in terms of process technology – plungers work from below, or from the side – require a press with two hydraulic plungers.

Major advantagesof this technique are shorter cycle times than compression molding, and minimal flash, since form filling finishes in a closed mold.

Disadvantages include a more pronounced degree of warpage than with compression molding, due to anisotropy.

Transfer systems with screw pre-plasticization and plunger feeding are an obvious choice for manufacturing parts which are subject to stress and require low dimensional tolerances. Such methods enable more reactive materials to be used, resulting in relatively short cycle times and accurate shot weights.

The processing procedure and the constitution of the mold determine how much flash can be expected. From larger or irregularly shaped molded parts, the flash is removed by hand, using a file or a grinding disc. The flash in breakthroughs or holes is normally removed by drilling, milling, using a triangular scraper, or – rarely – by die cutting. For large lots or complicated molding parts, bulk

deflashing machines are used. These machines blast a defined stream of media (typically thermoplastic granules, e.g. polyamide) out of a spinner or blow gun, to chip away the brittle flash. The blast media must be hard enough to chip the flash, but not so hard that the surface of the molded part is damaged. Bulk deflashing machines work in a continuous, automatic process.

Compression Molding

Hybrid Process Technologies

Deflashing

Bakelite® engineering thermosets exhibit very good thermal, mechanical and electrical properties. If exceptional temperature resistance (up to 300 °C) is required, an additional post curing after molding can be performed. Other material characteristics will also improve:

Internal stress reduction

Electrical insulation

Avoidance of post shrinkage at use

Media resistance

Modulus of elasticity

A stepwise post curing treatment achieves optimum property enhance-ment and is performed in an electrical or gas heated oven over several hours at defined temperatures (up to 220 °C). A Bakelite® thermoset’s glass transition temperature rises with the percentage of cure. The oven temperature must be maintained below this changing glass transition temperature. Grade-specific post-curing treatment procedures with heating rates and the timing of temperature plateaus are available on request.

Post Curing

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Bakelite® engineering thermosets are highly versatile. Numerous methods

can be applied to create the finished product.

Bonding of thermosets or of thermo-sets with metal is recommended if overmolding of inserts is not feasible, or if post assembly is necessary, as with a bearing, after moldings have been post cured for optimal performance. Thermoset parts can be screwed or glued with commonly used adhesives.

One- or two-component silicones can be used as temperature-tolerant and media-resistant elastic adhesives. One- or two-component epoxy glues are stronger, with good media resistance and thermal properties, but are less

elastic than silicone glues. Components not stressed by extreme temperatures or chemicals can be bonded with quick setting PUR, hot melt or acrylate adhesives (cyanide adhesives).

Consult the adhesive manufacturer to select a suitable adhesive for a given application. Producers with bonding solutions for the automotive industry are 3M (www.3m.com), Henkel (www.henkel.com), Sika (www.sika.com), Ashland (www.ashland.com) and many more.

In addition to the direct screw connections with self-tapping screws which are mainly used today, the following systems are possible:

Screw in threading hole

Screw/nut connection

Screw in molded-in insert

Screw in insert

Snap connections with other thermo-set or thermoplastic parts are also frequently used.

Welding of thermoset parts is not possible. Thermoset parts can be designed such that functions are

integrated and assembly steps eliminated or reduced.

Cutting is only used as a post-treatment when a shape cannot technically be produced by a mold. Important processing methods used are sawing, milling, machining and drilling. While cutting thermoset molding compounds, the material must be cooled sufficiently

to avoid excessive heating which can lead to material damage. Material is removed in chips, and because of friction, cutting edges wear out quickly. Diamond or carbide tools should be used as much as possible.

In general, the surface quality of thermoset molded parts is excellent, but grinding and polishing steps can be used for further smoothing and refining. Special grinding discs, as well

as belt grinders and disc wheels are used. Grinding occurs in stages, with increasingly finer grain abrasives. Cloth discs are used for polishing.

Coating of thermoset parts is not required for corrosion protection but can be done for aesthetics. For coating and printing, it is best to make sure both formulations are compatible. The preferred coating systems are

conventional topcoats that cure at relatively high temperatures. The electrostatic application of solvent-free powder coatings, followed by high temperature curing, is also common.

Engineering thermosets may be printed with silk screen or gravure printing methods. The surface should be degreased with a non fatty solvent. Depending upon the application, epoxy

resin-, acrylic resin-, or cellulose ester-based inks can be used, as well as two-pack, urethane-based inks.

Adhesive Bonding

Assembly

Welding

Cutting

Grinding and Polishing

Coating

Printing

Finishing

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The surface of engineering thermosets can be marked by electronic laser printing.

Metallization is performed for decorative purposes, or to impart electronic protection through various technologies,

such as chemical electrolysis, galvanization or vacuum deposition.

Once cured, the material is no longer reactive; direct reuse of grinded Bakelite® material for molding is not possible.

However, by re-compounding grinded material as a filler in combination with fresh (reactive) raw material, properties identical to those of the original material

can be achieved. For further information, contact our technical service department.

Incineration is a suitable method for disposal of reinforced engineering thermoset waste and allows recovery of the material’s intrinsic caloric energy, which is similar to coal’s.

The International Material Data System (IMDS) is a collective, computer-based system used primarily by automotive OEMs to manage the environmental impact of automotive components, and was developed in response to the European End of Life Vehicle Directive.

Upon request, we will provide component characterizations for the relevant Bakelite® engineering thermoset grades.

In co-operation with our partners, we select the appropriate Bakelite® engineering thermosets to fit customers’ application requirements. Tailored solutions can be developed as needed. Our services include:

Economical and technical recommendations on selection of material and tooling

Simulation of processing and molding properties

Optimization of flow and mold settings

Construction of in-house test series

Laser Marking

Metallization

Use of Recycled Material

IMDS

Technical Service – Engineering

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