ASTM D3294-97

Standard Specification for PTFE Resin Molded Sheet and Molded Basic Shapes

SCOPE
1.1 This specification establishes requirements and methods of test for the material, dimensions, and workmanship, and the physical and electrical properties of molded sheet in minimum thicknesses of 0.794 mm ( 1/32 in.) manufactured from PTFE resin molding materials.
1.2 This specification also establishes requirements for molded basic shapes made from resin molding and extrusion materials. This specification is for products 0.3 mm (12 in.) or less in a dimension parallel to and 12.7 mm (0.5 in.) or greater in the dimension perpendicular to the direction of the applied molding pressure.  
1.3 The values stated in SI units are to be regarded as the standard.
1.4 The following precautionary caveat pertains only to the test method portion, Section 7, of this specification. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Special attention is called to sections 13.2, 13.3, 13.6, 13.8, and A1.

General Information

• Status: Historical
• Publication Date: 09-Sep-1997
• ICS: 83.140.99 - Other rubber and plastics products
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.15 - Thermoplastic Materials

Relations

• Replaced By: ASTM D3294-03 - Standard Specification for PTFE Resin Molded Sheet and Molded Basic Shapes
• Effective Date: 10-Apr-2003
• Referred By: ASTM F1511-18(2023) - Standard Specification for Mechanical Seals for Shipboard Pump Applications
• Effective Date: 10-Sep-1997
• Referred By: ASTM F754-08(2015) - Standard Specification for Implantable Polytetrafluoroethylene (PTFE) Sheet, Tube, and Rod Shapes Fabricated from Granular Molding Powders
• Effective Date: 10-Sep-1997
• Referred By: ASTM F336-02(2023) - Standard Practice for Design and Construction of Nonmetallic Enveloped Gaskets for Corrosive Service
• Effective Date: 10-Sep-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3294 – 97
Standard Specification for
Polytetrafluoroethylene (PTFE) Resin Molded Sheet and
Molded Basic Shapes
This standard is issued under the fixed designation D 3294; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope * and Density of Plastics by Displacement
D 883 Terminology Relating to Plastics
1.1 This specification establishes requirements and methods
D 1505 Test Method for Density of Plastics by the Density-
of test for the material, dimensions, and workmanship, and the
Gradient Technique
physical and electrical properties of molded sheet in minimum
1 D 1600 Terminology for Abbreviated Terms Relating to
thicknesses of 0.794 mm ( ⁄32 in.) manufactured from PTFE
Plastics
resin molding materials.
D 1708 Test Method for Tensile Properties of Plastics by
1.2 This specification also establishes requirements for
Use of Microtensile Specimens
molded basic shapes made from resin molding and extrusion
D 1898 Practice for Sampling of Plastics
materials. This specification is for products 300 mm (12 in.) or
D 3293 Specification for PTFE Resin Molded Sheet
less in a dimension parallel to and 12.7 mm (0.5 in.) or greater
D 3892 Practice for Packaging/Packing of Plastics
in the dimension perpendicular to the direction of the applied
D 4591 Test Method for Determining Temperatures and
molding pressure.
Heats of Transitions of Fluoropolymers by Differential
1.3 The values stated in SI units are to be regarded as the
Scanning Calorimetry
standard.
E 94 Guide for Radiographic Testing
1.4 The following precautionary caveat pertains only to the
test method portion, Section 7, of this specification. This
3. Terminology
standard does not purport to address all of the safety concerns,
3.1 Definitions:
if any, associated with its use. It is the responsibility of the user
3.1.1 Definitions are in accordance with Terminology D 883
of this standard to establish appropriate safety and health
unless otherwise specified.
practices and determine the applicability of regulatory limita-
3.1.2 lot, n—one continuous production run or a uniform
tions prior to use. Special attention is called to 13.2, 13.3, 13.6,
blend of two or more production runs of one size sheet or
13.8, and A1.
molded basic shape.
NOTE 1—There is no similar or equivalent ISO standard.
3.2 Abbreviations:
3.2.1 Abbreviations are in accordance with Terminology
2. Referenced Documents
D 1600. PTFE is the abbreviation for polytetrafluoroethylene.
2.1 ASTM Standards:
D 149 Test Method for Dielectric Breakdown Voltage and 4. Classification
Dielectric Strength of Solid Electrical Insulating Materials
4.1 This specification covers the following three types of
at Commercial Power Frequencies
molded basic sheets and shapes:
D 618 Practice for Conditioning Plastics and Electrical
4.1.1 Type I—Premium; normally used for exacting electri-
Insulating Materials for Testing
cal, mechanical, or chemical applications.
D 638 Test Method for Tensile Properties of Plastics
4.1.2 Type II—General purpose; for electrical, mechanical,
D 792 Test Methods for Specific Gravity (Relative Density)
and chemical applications not requiring premium material.
4.1.3 Type III—Mechanical Grade; for noncritical chemical,
electrical, and mechanical applications.
This specification is under the jurisdiction of ASTM Committee D-20 on
4.1.4 Type IV—Utility; having no electrical requirements
Plastics, and is the direct responsibility of Subcommittee D20.15 on Thermoplastic
and with mechanical properties at a lower level.
Materials (Section D20.15.12).
Current edition approved Sept. 10, 1997. Published April 1998. Originally 4.2 Types I, II, and III may be subdivided into two grades as
published as D 3294 – 74. Last previous edition D 3294 – 91a.
follows:
This revision combines Specification D 3293 and Specification D 3294. Speci-
fication D 3293 has been withdrawn. A complete summary of changes is given at the
end of the text. Annual Book of ASTM Standards, Vol 08.02.
2 5
Annual Book of ASTM Standards, Vol 10.02. Annual Book of ASTM Standards, Vol 08.03.
3 6
Annual Book of ASTM Standards, Vol 08.01. Annual Book of ASTM Standards, Vol 03.03.
*A Summary of Changes section appears at the end of this standard.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3294
A
TABLE 1 Physical and Electrical Requirements for PTFE Sheets
4.2.1 Grade 1—made only from virgin resin.
4.2.2 Grade 2—may be made using reprocessed resin. Dielectric
Tensile Elonga-
B C
Strength Specific
A A D
4.3 The grades may be further subdivided into three classes
Types Strength tion (min) Porosity
(min) Volts Gravity
(min) psi Percent
as follows:
Per Mill
4.3.1 Class A—resistant to thermal dimensional change not
E
I 4500 300 600 2.15 to 2.18 Zero penetration
exceeding 0.5 %.
II 3000 225 500 2.14 to 2.19 Not required
III 2000 150 300 2.13 to 2.19 Not required
4.3.2 Class B—thermal dimensional change not exceeding
IV 1300 75 Not required 2.13 to 2.20 Not required
5.0 %.
A
See 13.2.
4.3.3 Class C—thermal dimensional change may exceed
B
See 13.3
5.0 %. C
See 13.4
D
See 13.6
4.4 A one-line system may be used to specify materials
E
PTFE sheet used for tank lining shall be Type I but shall have a specific gravity
covered by this specification. The system uses predefined cells
of 2.19 to 2.22.
to refer to specific aspects of this specification, as illustrated
below.
TABLE 2 Physical and Electrical Requirements for Basic Shapes
Specification
Dielectric
Tensile Strength Elongation %
Types Strength Volts Specific Gravity
Standard Number : Type : Grade : Class : Special
psi (min) (min)
Block : : : : Notes per mil (min)
:: : : : I 4800 325 1200 2.14 to 2.18
II 3200 240 850 2.14 to 2.19
III 1500 75 250 2.13 to 2.20
Example: Specification D 3294 – 97, I I A
For this example, the line callout would be Specification
D 3294 – 97,11A and would specify premium virgin form of
8. Dimensions
polytetrafluoroethylene that has all of the properties listed for
that Type, Grade, and Class in the appropriate specified
8.1 The size, shape, dimensional tolerances, and dimen-
properties, tables, or both, in the specification identified. A
sional stability shall be as specified in the contract or order.
comma is used as the separator between the standard Number
8.2 The tolerance on length and width shall be plus 6.3 mm
and the Type. Separators are not needed between the Type,
( ⁄4 in.), minus 0 mm (in.).
Grade, and Class. Provision for Special Notes is included so
that other information can be provided when required. An 9. Workmanship, Finish, and Appearance
example would be in Specification D 3295 where dimensions
9.1 Color—Type I shall be white to translucent, but may
and tolerances are specified for each AWG size within Type
have occasional spots. Types II, III, and IV are typically white,
and Class. When Special Notes are used, they should be
but may vary to light gray or light brown. For Types II, III, and
preceded by a comma.
IV occasional small gray, brown, or black spots shall not be
considered as cause for rejection.
5. Ordering Information
9.2 Finish—The material shall be as free as is commercially
5.1 The molded sheet or basic shapes covered in this
practical from surface blisters, wrinkles, cracks and other
specification shall be ordered stating the type, grade, and class
surface defects that might affect its serviceability. It shall also
and that they meet the requirements of this specification.
be commercially free of macroscopic voids, cracks, and foreign
inclusions.
6. Materials
9.3 Internal Defects—The moldings shall be as free as is
6.1 The sheet or molded basic shape from Types I, II, III, or
commercially practical of microscopic voids, cracks, and
IV shall be made from unpigmented PTFE as free of foreign
foreign inclusions.
matter as commercially practical.
10. Sampling
7. Requirements
10.1 For purposes of sampling, an inspection lot for exami-
7.1 The sheet covered by this specification shall meet the
nation and tests shall consist of all material of the same type,
physical and electrical requirements specified in Table 1 and
grade, and class and nominal size submitted for inspection at
paragraph 7.1.1 when tested by the methods given in Section
one time.
13.
10.2 The total quantity of sheet or basic shapes to be taken
7.2 The molded basic shapes covered by this specification
from each lot shall be approximately twice that estimated to be
shall meet the physical and electrical requirements specified in
required for the tests that are to be made, in order to permit
Table 2 and 7.1.1 when tested by the test methods given in
repeat tests without resampling.
Section 13.
10.3 The sheet or basic shapes selected for sampling may be
7.2.1 Melting Point—the melting point of all types of sheet
chosen at random from each lot. If the shipment consists of
and molded basic shapes shall be 327 6 10°C when tested in
more than one lot or “run” of material, each lot shall be
accordance with paragraph 13.8.
sampled separately. The average result of the specimens tested
shall conform to the requirements specified in this specifica-
See the ASTM Form and Style Manual. Available from ASTM Headquarters. tion.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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D 3294
11. Number of Tests surface and sample. Remove any tool marks resulting from
sample preparation which are not essentially parallel to the
11.1 Routine lot inspection tests shall consist of all the tests
long axis of the specimen by light sanding in a direction
specified in Table 1, Table 2, or Table 3.
parallel to such long axis.
11.2 The tests listed in Table 1 and Table 2, as they apply,
13.2.2 Testing shall be at a speed of 50.8 mm (2 in.)/min.
are sufficient to establish conformity of the PTFE sheet or basic
13.2.3 Determine elongation by using an initial jaw separa-
shapes to this specification. When the number of test speci-
tion of 22.2 mm (0.875 in.) and expressed as a percentage of
mens is not stated in the test method, single determination may
the initial jaw separation.
be made. If more than single determinations and separate
13.2.4 Alternative Specimens—When the shape of the
portions of the same sample are made, the results shall be
sample does not permit making the dumbbell as specified in
averaged. The single or average result shall conform to the
13.2.1 prepare specimens by turning a 0.8-mm ( ⁄32-in.) thick-
requirements prescribed in this specification.
walled tube from the shape, and cutting dumbbells from the
11.3 The properties listed in the Appendix X1 provide
tube wall in a direction perpendicular to the applied molding
additional information. The data shown are informational only
pressure, that is, with the long axis of the dumbbell parallel to
and should not be used for specification purposes.
the circumference of the tube. Lathe-turn the tube in such a
manner that the specimen is taken from the center of the
12. Test Conditions
original wall thickness. In the case of a rod, remove the outer
12.1 Conditioning of Specimens—Unless otherwise speci-
1.6 mm ( ⁄16 in.) before finish turning the outer diameter of the
fied in this specification, the test specimens shall be condi-
tube. Turn both inside and outside surfaces with a fine lathe
tioned in accordance with Procedure A of Practice D 618 for a
feed and sharp tools to permit the smoothest possible finish.
period of at least four h prior to test.
13.2.5 Cut sheets 1.6 mm ( ⁄16 in.) or under in thickness, five
12.2 Standard Temperature—Unless otherwise specified,
micro-specimens with the steel rule die and the dimensions
the tests shall be conducted at the standard laboratory tempera-
shown in Fig. 1 using a hydraulic or mechanical press.
ture of 23°C 6 1°C (73.4°C 6 1.8°F). Since the sheet or
Machine sheets thicker than 1.6 mm ( ⁄16 in. and thinner than
molded basic shape does not absorb water, the maintenance of
5 1
15.9 mm ( ⁄8 in.) to a thickness of 1.6 6 0.25 mm ( ⁄16 6 0.010
constant humidity during testing is not important.
in.) and five specimens from these reduced portions. From
sheets 15.9 mm ( ⁄8 in.) and over in thickness, a slice somewhat
13. Test Methods
thicker than 1.6 mm ( ⁄16 in.) shall be cut from one edge but not
13.1 Visual and Dimensional Inspection—Each of the
less than 12.7 mm ( ⁄2 in.) distance from that edge and both
sample PTFE sheets or molded basic shapes selected in
faces machined to a thickness of 1.6 6 0.25 mm ( ⁄16 6 0.010
accordance with Section 10 shall be visually and dimensionally
in.). In all cases of specimens reduced to 1.6 mm ( ⁄16 in.) by
inspected to verify their compliance with the requirements of
machining, tool marks shall be removed by light sanding in a
the standard. Occasional superficial flaws in PTFE sheet or
longitudinal direction.
molded basic shapes should be interpreted as neither affecting
13.3 Dielectric Strength—Determine the dielectric strength
the porosity nor soundness of the molding. Such flaws are
in accordance with Test Method D 149 using five specimens
scratches, edge cracks, and the adherence of resin flakes. Such
and the short-time test under oil, except as follows:
indications shall not be cause for rejection.
13.3.1 When 25.4 mm (1 in.) specimens are used, the
13.2 Tensile Strength and Elongation—Determine the ulti-
electrodes shall be 63.5 mm ( ⁄4 in.) in diameter, with edges
mate tensile strength and elongation in accordance with Test
rounded to a 0.8 mm ( ⁄32 in.) radius.
Method D 638 except as follows:
13.3.2 If the size of the molding does not permit 25.4 mm (1
13.2.1 Cut five microspecimens with the steel rule die and
in.) wide specimens, 12.7 mm ( ⁄2-in.) discs or strips 0.5 6 0.05
the dimensions shown in Fig. 1 using a hydraulic or mechani-
mm (0.020 6 0.002 in.) thick may be used with 1.6-mm
cal press. When cutting a specimen, back it by a hard surface
( ⁄16-in.) diameter electrodes with rounded edges.
board such as masonite or equal with a piece of thin cardboard
13.3.3 The specimen must extend sufficiently far beyond the
such as that used in a tabulating machine between said hard
electrode edge so that a flash-over does not occur.
13.4 Specific Gravity—Determine the spec
...