ASTM F3131-14(2023)

Standard Specification for Epoxy / Cotton Raw Materials for the Use in Bearing Cages

ABSTRACT
This specification covers basic characteristics required for porous laminated epoxy materials intended for use as instrument and thin-section ball-bearing retainers (cages), as well as the methods of determining these characteristics. It provides guidance with respect to material and test conditioning, performance, verification, and packaging and package marking.
SCOPE
1.1 This specification covers basic characteristics required for porous laminated Epoxy materials intended for use as instrument and thin-section ball-bearing retainers (cages) and the methods of determining these characteristics.  
1.2 Forms—Sheets and Rolled Tubes are recommended forms of laminated material covered by this specification.  
1.3 Intended Use—Materials produced to this specification are intended for use as ball bearing retainers (cages). Temperature range is limited to 284 °F (140 °C) and below.  
1.4 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2022
• ICS: 21.100.20 - Rolling bearings
• Technical Committee: F34 - Rolling Element Bearings
• Drafting Committee: F34.06 - Aerospace

Relations

• Refers: ASTM D229-19 - Standard Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
• Effective Date: 01-Mar-2019
• Refers: ASTM E1640-13(2018) - Standard Test Method for Assignment of the Glass Transition Temperature By Dynamic Mechanical Analysis
• Effective Date: 15-Mar-2018
• Refers: ASTM D790-17 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Jul-2017
• Refers: ASTM D790-15 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM D790-15e1 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM D2257-98(2012) - Standard Test Method for Extractable Matter in Textiles
• Effective Date: 01-Feb-2012
• Refers: ASTM D695-10 - Standard Test Method for Compressive Properties of Rigid Plastics
• Effective Date: 01-Apr-2010
• Refers: ASTM D229-09b - Standard Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
• Effective Date: 01-Oct-2009
• Refers: ASTM E1640-09 - Standard Test Method for Assignment of the Glass Transition Temperature By Dynamic Mechanical Analysis
• Effective Date: 01-Sep-2009
• Refers: ASTM D229-09a - Standard Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
• Effective Date: 01-Jun-2009
• Refers: ASTM D229-09 - Standard Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
• Effective Date: 15-Jan-2009
• Refers: ASTM D618-08 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2008
• Refers: ASTM D695-08 - Standard Test Method for Compressive Properties of Rigid Plastics
• Effective Date: 01-Aug-2008
• Refers: ASTM D792-08 - Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
• Effective Date: 15-Jun-2008
• Refers: ASTM D790-07 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Sep-2007

Overview

ASTM F3131-14(2023) - Standard Specification for Epoxy/Cotton Raw Materials for the Use in Bearing Cages provides comprehensive requirements for porous laminated epoxy materials designed specifically for instrument and thin-section ball-bearing retainers (also known as bearing cages). The standard details material forms, conditioning, performance properties, verification procedures, packaging, and marking to ensure the materials reliably serve in demanding bearing applications. By defining key dimensional tolerances and test methods, ASTM F3131 enhances product consistency, safety, and quality across international supply chains.

Key Topics

• Material Forms: Covers epoxy/cotton composites supplied as sheets and rolled tubes for manufacturing ball bearing cages.
• Intended Use: Materials are specified for use in bearing cages operating at temperatures up to 284°F (140°C), making them suitable for high-precision applications.
• Types and Construction: Materials are constructed from woven cotton fabric substrates impregnated with non-plasticized epoxy resin, ensuring optimal mechanical and thermal properties for bearing cages.
• Conditioning and Testing: Strict procedures for material and test sample conditioning, including control of temperature and humidity, are specified to ensure repeatable and reliable test results.
• Performance Requirements: Minimum values for compressive and flexural strength, density, glass transition temperature (Tg), water absorption, bond strength, and dimensional tolerances are defined to maintain product integrity.
• Quality Assurance: Procedures for material verification, appearance, and dimensional inspection are provided, as well as defect classification and acceptance quality levels.
• Packaging and Marking: All materials must be packaged according to vendor or contract requirements and marked per federal standards to ensure traceability and safe handling.

Applications

Epoxy/cotton laminated materials standardized under ASTM F3131 are widely used in industries where dependable, lightweight, and stable bearing cages are critical. Typical applications include:

• Aerospace and Instrument Bearings: Due to precision requirements and stringent temperature limits, these materials are ideal for aerospace components, navigation instruments, and other high-reliability devices.
• Industrial Machinery: Thin-section and miniature bearings in robotics, medical devices, and precision machinery benefit from these high-performance materials.
• Custom Mechanical Assemblies: Engineers seeking customizable sheet or tube forms to machine into specialized bearing cages or separators will find this standard supportive.
• Procurement and Compliance: Bearing manufacturers, procurement managers, and quality control teams rely on ASTM F3131 to verify raw material conformance, manage supplier quality, and ensure regulatory compliance.

Related Standards

Several standards referenced within ASTM F3131 reinforce the rigorous approach to quality and performance:

• ASTM D695: Test Method for Compressive Properties of Rigid Plastics
• ASTM D790: Test Methods for Flexural Properties of Plastics and Electrical Insulating Materials
• ASTM D792: Test Methods for Density and Specific Gravity by Displacement
• ASTM D570: Test Method for Water Absorption of Plastics
• ASTM D229: Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
• ASTM E1640: Test Method for Assignment of Glass Transition Temperature by Dynamic Mechanical Analysis
• ANSI/ASQC Z1.4: Sampling Procedures and Tables for Inspection by Attributes
• MIL-STD-129: Military Marking for Shipment and Storage

Practical Value

By following ASTM F3131-14(2023), manufacturers and suppliers can:

• Ensure uniformity and reliability of epoxy/cotton bearing cage materials
• Meet international trade and regulatory requirements
• Streamline procurement and inspection processes with clear tolerances and testing protocols
• Minimize product failures by relying on verified material properties and defect classifications

Keywords: epoxy cotton, bearing cages, ball bearing retainers, laminated materials, ASTM F3131, material specification, quality assurance, industrial standards, aerospace, instrument bearings, flexural strength, compressive strength, packaging, dimensional tolerances.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:F3131 −14 (Reapproved 2023)
Standard Specification for
Epoxy / Cotton Raw Materials for the Use in Bearing Cages
This standard is issued under the fixed designation F3131; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D695 Test Method for Compressive Properties of Rigid
Plastics
1.1 This specification covers basic characteristics required
D790 Test Methods for Flexural Properties of Unreinforced
for porous laminated Epoxy materials intended for use as
and Reinforced Plastics and Electrical Insulating Materi-
instrument and thin-section ball-bearing retainers (cages) and
als
the methods of determining these characteristics.
D792 Test Methods for Density and Specific Gravity (Rela-
1.2 Forms—Sheets and Rolled Tubes are recommended
tive Density) of Plastics by Displacement
forms of laminated material covered by this specification.
D2257 Test Method for Extractable Matter in Textiles
1.3 Intended Use—Materials produced to this specification E1640 Test Method for Assignment of the Glass Transition
Temperature By Dynamic Mechanical Analysis
are intended for use as ball bearing retainers (cages). Tempera-
ture range is limited to 284 °F (140 °C) and below.
2.2 ANSI/ASQC Standards:
ANSI/ASQC Z1.4 Sampling Procedures and Tables for In-
1.4 Units—The values stated in inch-pound units are to be
spection by Attributes
regarded as the standard. The values given in parentheses are
mathematical conversions to SI units that are provided for 2.3 Federal Standard:
information only and are not considered standard. MIL-STD-129 Military Making for Shipment and Storage
1.5 This standard does not purport to address all of the
3. Material and Test Conditioning
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1 Material Conditioning Prior to Tests: (designation as
priate safety, health, and environmental practices and deter- follows)
mine the applicability of regulatory limitations prior to use. 3.1.1 Anumber indicating in degrees Celsius the condition-
1.6 This international standard was developed in accor- ing temperature, or
dance with internationally recognized principles on standard- 3.1.2 A number indicating relative humidity, whenever hu-
ization established in the Decision on Principles for the midity is controlled, or a word to indicate immersion in liquid.
Development of International Standards, Guides and Recom-
3.2 The numbers shall be separated from each other by a
mendations issued by the World Trade Organization Technical
slant marks. A sequence of conditions shall be denoted by use
Barriers to Trade (TBT) Committee.
of a plus (+) sign between successive conditions. “Des” shall
be used to indicate desiccation over anhydrous calcium chlo-
2. Referenced Documents
ride. A capital letter “T” (test condition) following the prior
2.1 ASTM Standards: material conditioning designation shall be separated by a
D618 Practice for Conditioning Plastics for Testing colon, with the testing condition noted in the same format as
D229 Test Methods for Rigid Sheet and Plate Materials the material conditioning. Temperature and relative humidity
Used for Electrical Insulation tolerancesshallbeinaccordancewithPracticeD618Section7,
D570 Test Method for Water Absorption of Plastics unless otherwise specified.
3.2.1 Examples:
3.2.1.1 C-96/35/90—Humidityconditioning–96hat95 °F,
(35 °C) and 90 % relative humidity.
This specification is under the jurisdiction ofASTM Committee F34 on Rolling
Element Bearings and is the direct responsibility of Subcommittee F34.06 on 3.2.1.2 E-48/50—Temperature conditioning – 48 h at
Aerospace.
122 °F, (50 °C).
Current edition approved Jan. 1, 2023. Published January 2023. Originally
approved in 2014. Last previous edition approved in 2014 as F3131 – 14. DOI:
10.1520/F3131-14R23.
2 3
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F3131−14 (2023)
3.2.1.3 D1-24/23—Immersion conditioning – 24 h in dis- 5.2 Required test data shall be requested at the time the
tilled water at 73.4 °F, (23 °C), followed by E-1/105 – tem- purchase order is submitted and listed on the purchase order.
perature conditioning–1hat221°F, (105 °C).
6. Order of Precedence
3.3 Standard Procedures:
3.3.1 Procedure A:
6.1 In the event of a conflict between the text of this
3.3.1.1 Condition A—40/23/50 for thickness equal or less
specification and references cited herein, the text of this
than 0.250 in., (7 mm) or Condition A-88/23/50 for thickness
specification takes precedence. Nothing in this specification,
greaterthan0.250in.,(7 mm)StandardLaboratoryatmosphere
however, supersedes applicable laws and regulations unless a
for a minimum of either 40 h or 88 h, dependent on thickness,
specific exemption has been obtained.
at 73.4 °F (23 °C) and 50 % relative humidity.
3.3.2 Procedure D:
7. Performance Requirement
3.3.2.1 Condition D —24/23 See example above.
7.1 Tube—Performance requirements for tube laminated
3.3.2.2 Condition D—24/23 – Immersion conditioning –
materials specified in Table 1.
24 h at 73.4 °F, (23 °C).
3.3.2.3 Condition D—48/50 – Immersion conditioning – 48 7.2 Sheet—Performance requirements for sheet laminated
h at 122 °F, (50 °C).
materials, specified in Table 2.
3.3.3 Procedure E:
7.3 Construction—Tubes and Sheets shall consist of cotton
3.3.3.1 Condition E-1/150:T-150 –Temperature condition-
base material (reinforcement) as described in 4.1, impregnated
ing–1hat302°F, (150 °C) - immediately followed with Test
and bonded with a non-plasticized Epoxy resin. Tubes will be
at 302 °F, (150 °C).
made by passing the impregnated material over heated rolls
3.3.3.2 Condition E—48/50 See example above.
and winding the heated material onto a mandrel while applying
3.3.3.3 ConditionE—168/185–Temperatureconditioning–
pressure to the material/mandrel. The overwrapped mandrel is
168 h at 365 °F, (185 °C).
then placed in an oven to cure the tube. Sheets will be made by
stacking pre-cut impregnated material between steel plates and
4. Classification
loadedintoapressapplyingheatandpressuretocurethesheet.
4.1 The material shall be furnished in the following types
7.4 Base Materials:
and forms as specified:
7.4.1 Cotton Fabric Construction—Material shall consist of
Type Description
a woven cotton fabric substrate impregnated and bonded with
2 2
FB Rolled tube made from cotton fabric weighing 4 oz/yd (0.14 kg/m )
an Epoxy resin matrix and processed to meet the requirements
or less, with a nominal thread count of 80 by 80 threads per in.
(31.5 cm by 31.5 cm). Thread tolerance of ± 5 %.
ofthisspecification,(see4.1).Finishedfabricshallbede-sized,
washed, and bleached, with remaining impurities per Test
2 2
FBFW Rolled tube made from cotton fabric weighing 4 oz/yd (0.14 kg/m )
or less, with a nominal thread count of 100 by 100 threads per in. Method D2257 Extractable Matter, not greater than 1.5 % after
(39.4 cm by 39.4 cm). Thread tolerance of ± 5 %.
finishing.
2 2
FBEFW Rolled tube made from cotton fabric weighing 3 oz/yd (0.1 kg/m )or
7.5 Property Values—Tubes shall conform to the property
less, with a nominal thread count of 130 by 130 threads per in. (51.2
values shown in Table 1, when tested in accordance with
cm). Thread tolerance of ± 5 %.
Section 8. The property value requirements for special sizes of
tubesshallbeasspecifiedinthepurchaseorder(seeSection5).
5. Ordering Information
Sheets shall conform to the property values shown in Table 2,
5.1 Procurement documents should specify the following:
when tested in accordance with Section 8. The property value
5.1.1 Title, designation, and date of this specification,
requirements for special sizes of sheets shall be as specified in
5.1.2 Type required (see Section 4),
the purchase order (see Section 5).
5.1.3 Dimensions required, and
5.1.4 Special marking required (see 10.2). 7.6 Dimensional:
TABLE 1 Performance Requirements for Tubes
Condition ASTM Unit FB FBFW FBEFW
Test
Method
A
Compressive Strength Axial A D695 Min. psi 27 000 27 000 27 000
A
Compressive Strength Axial A D695 Min. kpsi 255 255 285
Modulus
A
Density (Range) A D792 gm/cc 1.24 – 1.34 1.28 – 1.38 1.30 – 1.38
Tg by DMA A E1640 Min. °C 150 150 150
Water Absorption (ID range of 0.25 D – 24/23 D570 Max. % Wall < 0.062 in. Wall < 0.125 in. Wall <0.250 in. Wall <0.5 in.
in. (0.635 cm) to 8.0 in. (20.3 cm)) (0.16 cm) 1.5 (0.32 cm) 1.0 (0.63 cm) 0.75 (1.27 cm) 0.5
A
Pounds per square inches (psi). 1 psi = 6.8948 kPa. Test is limited to tubes 0.250 in. (0.635 cm) and greater ID. One specimen to be taken from center of sample tube.
The other two specimens to be taken 1 in. (2.54 cm) from each end of the sample tube.
F3131−14 (2023)
TABLE 2 Performance Requirements for FB Sheets
A
Condition ASTM Unit Thickness (in.)
Test 0.031 0.062 0.094 0.125 0.188 0.250 0.500 0.750 1.000 1.001 – Max.
Method
Flexural
strength
Lengthwise: A D790 Min. psi 19 000 19 000 19 000 19 000 19 000 19 000 19 000 18 000 16 500 16 000
Crosswise: Min. psi 16 000 16 000 16 000 16 000 16 000 16 000 16 000 15 000 12 500 12 500
Flexural
strength
Lengthwise: A D790 Min. kpsi . 900 900 900 900 900 900 900 900 900
Modulus
Crosswise: . . Min. kpsi . 750 750 750 750 750 750 750 750 750
modulus
Tg by DMA A E1640 Min. °C 150 150 150 150 150 150 150 150 150 150
Bonding A D229 Min. lbs. . . . . . . 1 800 1 800 2 200 2 200
strength D-48/50 1 700 1 700 2 200 2 200
Water ab- D – 24/23 D570 Max. % 1.50 1.25 1.00 1.00 0.75 0.75 0.50 0.50 0.25 0.25
sorption D570
Silicone con- E-168/185 Customer Max. ppm 50 50 50 50 50 50 50 50 50 50
tent Specific
A
1 in. = 2.54 cm. 1 lb = 0.45 kg. 1 psi = 6.8948 kPa.
B
Maximum thickness tested shall be 2.000 in. (5.08 cm).

F3131−14 (2023)
7.6.1 Diameter of Tubes Rolled Round (TRR)—Range of 7.10 Color—The natural color of the laminate may vary and
sizesfortubesrolledroundshallbeasspecifiedinTable3.The is not a cause for rejection.
inside diameter and outside diameter shall be included in the
7.11 Surface Finish—Laminate shall be finished to meet the
part number. An example of a part number for a rolled tube
customer requirements.
with an inside diameter of 0.188 in., (0.478
...