ASTM D7310-07
(Guide)Standard Guide for Defect Detection and Rating of Plastic Films Using Optical Sensors
Standard Guide for Defect Detection and Rating of Plastic Films Using Optical Sensors
SIGNIFICANCE AND USE
Defects in film are not acceptable to the end-user as there is a reduction in the fitness-for-use, in many applications. This document is intended to be a guide to assist users in the inspection and observation of defects.
This guide is applicable in a laboratory environment as a quality control or as a research tool. It is also appropriate for use in any commercial process used to produce film including calendering and solvent casting.
This guide is also suitable for use as an evaluation or screening tool for materials intended to be used in other processes where defects of this nature are also critical, such as fiber spinning and nonwovens.
The individual user must agree upon the relationship between the criteria and acceptance for fitness-for-use and the observed defects, as it varies by polymer and application. This is attained by the collection of data over a time-period to establish acceptable control limits.
SCOPE
1.1 This guide is intended to provide suggested approaches and criteria for the observation of defects in various types of plastic film, by means of an optical scanning system.
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 health practices and determine the applicability of regulatory limitations prior to use.Note 1
There is no known ISO equivalent to this standard.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7310–07
Standard Guide for
Defect Detection and Rating of Plastic Films Using Optical
Sensors
This standard is issued under the fixed designation D7310; 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 4.2 This guide is applicable in a laboratory environment as
a quality control or as a research tool. It is also appropriate for
1.1 This guide is intended to provide suggested approaches
use in any commercial process used to produce film including
and criteria for the observation of defects in various types of
calendering and solvent casting.
plastic film, by means of an optical scanning system.
4.3 This guide is also suitable for use as an evaluation or
1.2 This standard does not purport to address all of the
screening tool for materials intended to be used in other
safety concerns, if any, associated with its use. It is the
processes where defects of this nature are also critical, such as
responsibility of the user of this standard to establish appro-
fiber spinning and nonwovens.
priate safety and health practices and determine the applica-
4.4 The individual user must agree upon the relationship
bility of regulatory limitations prior to use.
between the criteria and acceptance for fitness-for-use and the
NOTE 1—There is no known ISO equivalent to this standard.
observed defects, as it varies by polymer and application. This
is attained by the collection of data over a time-period to
2. Referenced Documents
establish acceptable control limits.
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
5. Apparatus
5.1 Extruder—Adeviceformeltingpolymerthatproducesa
3. Terminology
flat or blown (tubular) film, with sizes varying from lab-scale
3.1 Definitions of Terms Specific to This Standard:
to production-scale.
3.1.1 defect—for the purpose of this guide, any entity in the
NOTE 2—Although this technique is utilized for many different pro-
filmthatislargeenoughtobedetectedbyanopticalsensorand
cesses used for producing films, the extrusion systems described in the
is either polymeric in nature or caused by degradation, external
following section represent the more prevalent process used.This is not to
contamination, undispersed additives or pigments, or similar
imply that the guidance provided for utilizing this type of instrumentation
sources.
cannot be applied to other processes or other applications.
5.1.1 Flat Film Extrusion—An extrusion system that pro-
4. Significance and Use
duces a flat film that is quenched immediately after extrusion
4.1 Defects in film are not acceptable to the end-user as
by means of one or more cooling devices such as an air knife,
there is a reduction in the fitness-for-use, in many applications.
chill roll or water bath.
This document is intended to be a guide to assist users in the
5.1.2 Blown or tubular extrusion –An extrusion system that
inspection and observation of defects.
produces a tubular “bubble” of film from a circular die,
equipped with an air-ring to cool the polymer.
5.2 Screen Pack—Although commonly used in commercial
This guide is under the jurisdiction of ASTM Committee D20 on Plastics and
or semi-commercial environments, screen packs are not gen-
is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.
erally used in laboratory units intended for research or quality
Current edition approved Sept. 1, 2007. Published September 2007. DOI:
10.1520/D7310-07.
functions.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.3 Defect Detection System—An optical scanning system
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
with a light source, an analog or digital camera, and an image
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. processor. The optical characteristics of the camera are critical
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7310–07
NOTE 5—One method for determining residence time is to introduce a
for detecting small (30 µm) defects and it is important that the
different pigmented polymer into the extruder and measuring the time
instrument manufacturer be informed of the detection needs
required for the pigment to travel from the throat, or point of introduction,
when choosing a system.
to the final product.
NOTE 3—Other types of detection systems than the ones described in
Therelationofthescrewspeed(extruderoutput)andtake-up
this guide are available, but are outside the scope of the guide, and are not
speed shall be set to produce film of suitable thickness to
defined.
measure defects. After these conditions are determined, the
5.3.1 Transmission Mode (Transparent or Translucent Film
same conditions must be used consistently to ensure repeatable
Configuration)—Thecameraislocateddirectlyacrossfromthe
results for a given type and grade of material. A nitrogen
light source with the film passing between them. With this
blanket is recommended on the feed throat to eliminate oxygen
system, the film is illuminated and the camera captures images
in the extruder.
of the defects and sends them automatically to the image
6.1.1.2 Purging—The extruder shall be cleaned thoroughly
processor, which measures the size and frequency of the
prior to the introduction of the material to be evaluated.This is
defects. Fig. 1 is a basic outline of this setup.
accomplished by introducing some form of concentrate addi-
5.3.2 Reflection Mode (Opaque Film Configuration)—The
tive mixture, such as an antioxidant, prior to introducing the
light source and camera are both located above and at equal
sample, or simply running a clean, highly stable, compatible
angles, typically 45°, to the film. This allows the camera to
material through the extruder until the film appears clear or
detect the defect images by reflectance off the film, and the
when the defect count, as measured by the optical monitoring
images are sent to the processor that measures the size and
system, has stabilized. After introducing the material to be
frequency of the defects. Fig. 2 depicts a basic outline of this
evaluated into the extruder, allow enough time for the preced-
type of setup.
ing material to completely purge. If studies of similar materials
are being performed, the purge time is established prior to
6. Procedure
subsequent evaluations. (See Appendix X1 for guidelines on
6.1 Extrusion
the use of a Control Resin.)
6.1.1 Laboratory Environment—Laboratory determinations
NOTE 6—The need for adequate equilibration cannot be overstressed.
are much more controlled than determinations conducted
Not only must care be taken to provide adequate time for the system to
online in production environments. Their applicability is more
stabilizeafterpurging,butalsotoallowadequatemonitoringtimeincases
suited to research and quality functions, and consequently, the
where intermittent defect flurries occur in a stable system due to
requirements and control levels are more stringent.
non-uniformity of the sample itself (see Appendix X2).
6.1.1.1 Extruder Conditions—In order to count defects in
6.1.2 Production (Commercial) Environment
extruded film, the proper temperatures, especially on the die
6.1.2.1 The general purpose of optical sensors used in a
zone, must have been reached. In general, it is best for the set
production environment is continual monitoring, both for the
point temperature to be at or above the melt point of the
consistencyoftheproductandtodetectanydisturbancesinthe
polymer, but not enough above it to cause degradation of the
systems or processes that introduce an unacceptable level of
material.
defects.
NOTE 4—Specific extruder conditions and preconditioning of material,
6.1.2.2 Extruder Conditions—When monitoring film pro-
such as drying, if required, are determined by the system used and the
duced on a commercial scale, the extruder conditions shall be
material being evaluated, in conjunction with guidance provided by the
determined by the constraints of the production requirements,
instrument manufacturer, material supplier, or material specification
that is, conditions are not changed from the normal operating
determine. In addition, the extruder screw speed shall be set such that the
conditions for the purpose of defect detection. When the intent
residence time of the polymer is adequate to entirely melt and mix the
is to evaluate the film for defects, it is important to have
polymer, but not long enough to cause degradation (less than 10 minutes
is best to prevent formation of defects in the extruder). processes in place to ensure that proper operating guidelines
FIG. 1 Transmission Mode (Clear/Translucent Film)
D7310–07
FIG. 2 Mode (Opaque Film)
are followed. Variables such as temperature, film gauge, etc. 6.2.3.2 Categorize and count the defects according to size
must be taken into account to achieve repeatable results. classes or other specifications as defined by internal standards
or agreement between supplier and user.
6.1.2.3 Purging—It is normally not possible to purge pro-
(a) Typical units for reporting include defects per square
duction extrusion equipment with any cleaning or reference
meter (or square foot), defect area in parts per million (PPM
material. In this case, the system must be set up to produce
defect area = total defect area/total area measured), or any
commercially acceptable product and the monitoring system
other method as defined by internal standards or agreement
essentially serves to track deviations from the acceptable
between supplier and user.
levels.Inthiscase,theacceptablelevelsshallbedeterminedby
the accepted fitness for use set by the application or by
NOTE 10—Examples of data presentation for film defect detection and
agreement
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