ASTM D352-23

Standard Test Methods for Pasted Mica Used in Electrical Insulation

SIGNIFICANCE AND USE
4.1 This test determines the compressive creep under laboratory conditions or under conditions that are possibly encountered during manufacture of electrical equipment. It has special significance if the material to be tested is applied as commutator segment insulation. It serves as a measure under specified conditions of the ability of the material to resist deformation while under compressive load, during exposure to elevated temperature for a specified time. This test is suitable for acceptance tests and for manufacturing control.
SCOPE
1.1 These test methods cover the testing of bonded mica splittings and bonded mica paper to be used for commutator insulation, hot molding, heater plates, and other similar insulating purposes.  
1.2 These test methods appear in the following sections:
Test  
Sections  
Compressive Creep  
4 – 10    
Dielectric Strength  
38 – 41    
Mica or Binder Content  
19    
Molding Test  
31 – 36    
Organic Binder  
20 – 24    
Resistivity  
42 – 46    
Silicone Binder  
25 – 30    
Stability Under Heat and Pressure  
11 – 18    
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.4 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. See 40.1 and 45.1 for specific hazard statements.  
1.5 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-Jul-2023
• ICS: 29.035.50 - Mica based materials
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.01 - Electrical Insulating Products

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: D352 − 23
Standard Test Methods for
1
Pasted Mica Used in Electrical Insulation
This standard is issued under the fixed designation D352; 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 Dielectric Strength of Solid Electrical Insulating Materials
at Commercial Power Frequencies
1.1 These test methods cover the testing of bonded mica
D257 Test Methods for DC Resistance or Conductance of
splittings and bonded mica paper to be used for commutator
Insulating Materials
insulation, hot molding, heater plates, and other similar insu-
D1711 Terminology Relating to Electrical Insulation
lating purposes.
1.2 These test methods appear in the following sections:
3. Terminology
Test Sections
3.1 Definitions:
Compressive Creep 4 – 10
3.1.1 For definitions of terms relating to electrical
Dielectric Strength 38 – 41
insulation, refer to Terminology D1711.
Mica or Binder Content 19
Molding Test 31 – 36
3.2 Definitions of Terms Specific to This Standard:
Organic Binder 20 – 24
3.2.1 binder content, n, (of pasted mica)—the percent by
Resistivity 42 – 46
weight of binder relative to the original weight of a specimen
Silicone Binder 25 – 30
Stability Under Heat and Pressure 11 – 18
as determined by procedures specified herein.
1.3 The values stated in inch-pound units are to be regarded 3.2.1.1 Discussion—Binder content includes any residual
as standard. The values given in parentheses are mathematical solvent. Pasted mica materials not fully cured (such as molding
conversions to SI units that are provided for information only and flexible plates) possibly contain appreciable quantities of
and are not considered standard. solvent in the binder. This solvent is usually later removed
when the material is cured in the manufacture of electrical
1.4 This standard does not purport to address all of the
equipment. In such cases, the binder content after cure is less
safety concerns, if any, associated with its use. It is the
(by the amount of solvent removed) than would be determined
responsibility of the user of this standard to establish appro-
by this method. To determine the binder content after cure of
priate safety, health, and environmental practices and deter-
materials that are not fully cured, but subsequently will be, it is
mine the applicability of regulatory limitations prior to use.
necessary, before initially weighing the specimen, to heat the
See 40.1 and 45.1 for specific hazard statements.
specimen for a time and at a temperature that depends upon the
1.5 This international standard was developed in accor-
material from which the specimen is prepared.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 3.2.2 compressive creep, n—the change in thickness of a
Development of International Standards, Guides and Recom- bonded micaceous material resulting from exposure to elevated
mendations issued by the World Trade Organization Technical temperature for a specified time while a specimen is under a
Barriers to Trade (TBT) Committee. specified compressive load.
3.2.3 mica content, n, (of pasted mica)—the percent by
2. Referenced Documents
weight of mica relative to the original weight equal to 100 %
2
2.1 ASTM Standards:
minus the binder content as determined by procedures specified
D149 Test Method for Dielectric Breakdown Voltage and
herein.
COMPRESSIVE CREEP
1
These test methods are under the jurisdiction of ASTM Committee D09 on
4. Significance and Use
Electrical and Electronic Insulating Materials and are the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Products.
4.1 This test determines the compressive creep under labo-
Current edition approved Aug. 1, 2023. Published August 2023. Originally
ratory conditions or under conditions that are possibly encoun-
approved in 1932. Last previous edition approved in 2016 as D352 – 97 (2016).
DOI: 10.1520/D0352-23.
tered during manufacture of electrical equipment. It has special
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
significance if the material to be tested is applied as commu-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
tator segment insulation. It serves as a measure under specified
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. conditions of the ability of the material to resist deformation
Copyrig
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D352 − 97 (Reapproved 2016) D352 − 23
Standard Test Methods for
1
Pasted Mica Used in Electrical Insulation
This standard is issued under the fixed designation D352; 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
1.1 These test methods cover the testing of bonded mica splittings and bonded mica paper to be used for commutator insulation,
hot molding, heater plates, and other similar insulating purposes.
1.2 These test methods appear in the following sections:
Test Sections
Compressive Creep 4 – 10
Dielectric Strength 38 – 41
Mica or Binder Content 19
Molding Test 31 – 36
Organic Binder 20 – 24
Resistivity 42 – 46
Silicone Binder 25 – 30
Stability Under Heat and Pressure 11 – 18
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.4 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. See 40.1 and 45.1 for specific hazard statements.
1.5 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D257 Test Methods for DC Resistance or Conductance of Insulating Materials
D1711 Terminology Relating to Electrical Insulation
1
These test methods are under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and are the direct responsibility of Subcommittee
D09.01 on Electrical Insulating Products.
Current edition approved May 15, 2016Aug. 1, 2023. Published May 2016August 2023. Originally approved in 1932. Last previous edition approved in 20082016 as
ε1
D352 – 97 (2008) – 97 (2016). . DOI: 10.1520/D0352-97R16. 10.1520/D0352-23.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D352 − 23
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms relating to electrical insulation, refer to Terminology D1711.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 binder content, n, (of pasted mica)—the percent by weight of binder relative to the original weight of a specimen as
determined by procedures specified herein.
3.2.1.1 Discussion—
Binder content includes any residual solvent. Pasted mica materials not fully cured (such as molding and flexible plates)
maypossibly contain appreciable quantities of solvent in the binder. This solvent is usually later removed when the material is cured
in the manufacture of electrical equipment. In such cases, the binder content after cure is less (by the amount of solvent removed)
than would be determined by this method. To determine the binder content after cure of materials that are not fully cured, but
subsequently will be, it is necessary, before initially weighing the specimen, to heat the specimen for a time and at a temperature
that depends upon the material from which the specimen is prepared.
3.2.2 compressive creep, n—the change in thickness of a bonded micaceous material resulting from exposure to elevated
temperature for a specified time while a specimen is under a specified compressive load.
3.2.3 mica content, n, (of pasted mica)—the percent by weight of mica relative to the original weight equal to 100 % minus the
binder content as determined by procedures specified herein.
COMPRESSIVE CREEP
4
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