SCC Lesson 2 PowerPoint

Report
Quality Assurance and
Nondestructive
Evaluation of Composite
Materials
Outline,
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Design and Detectability
Manufacturing and Fabrication Testing-NDT
In-Service Inspection-NDT
Damage Assessment and Repair Inspection
Visual Inspection
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Section 2
Typical Conditions-Laminates
Typical Conditions-Honeycomb
Mechanical Methods
Measuring composites
Tools, UT Thickness, Magnamike
Acceptance Criteria
Fiberglass and translucent materials, Hot light Inspection
Manual and Automated Tap Test
Inspecting known damage
Foreign Material, Foreign Object Detection, (FOD), Foreign Object
Evaluation and/or Elimination (FOE)
Design,
Section 2
The strength of any given laminate under a prescribed set of
loads is probably best determined by “conducting a test”.
However, when many laminates and different loading
conditions are being considered, as in a preliminary design
study, analysis methods for estimation of laminate strength
become desirable.
Because the stress distribution throughout the fiber and
matrix regions of all the plies of a laminate is quite complex,
precise analysis methods are not available. However,
reasonable methods do exist which can be used to guide the
preliminary design process.
Design,
Section 2
• Key Design Considerations
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Material Selection
Processing/Fabrication Methods
Structural Considerations
Environmental Effects & Protection
Sandwich Construction
Design,
Section 2
Aircraft Composite Design Process
1. Determine requirements and loads
2. Select structural configuration
3. Select material, fabric, thickness, style, ply sequence
4. Calculate laminate properties
Strength, stiffness, strain to failure, etc
5. Calculate stress induced by loads
Go back to 3 if stress × 1.5 >1
6. Evaluate cost versus weight
Go back to 2 if high cost or weight
7. Build & test prototype – final design
Design,
Section 2
Design concern example:
With failure rates still high for turbine blades (a
Sandia Lab survey of wind energy plants
documented rates as high as 20% failure) and
down-time costly and bad for business, blade
designers and manufacturers have turned to the
best practices for designing composites.
Design,
Section 2
• Select Structural Configuration
– Important to have a thorough knowledge of the advantages and
disadvantages of the various fabrication / manufacturing
techniques
– Design for Manufacture
• Usually a specific structural configuration is selected for
– Ease of construction
– Low tooling and fabrication costs
– Lightweight
• Once the type of composite structure has been selected =
preliminary structural sizing of the components and
laminates can proceed
– Using standard structural analytical techniques
– Together with simple optimization techniques and equations
Design,
Section 2
Design and Analysis of Structures
• Analysis of composite components is difficult
• Dynamic loads are especially hard to consider
• Design tools are less developed than those for
conventional materials
• Testing is still widely used to validate design
and analysis models
Design,
Section 2
Design concerns of Composites
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Environmental degradation of resin dominated properties
Notch sensitivity
Impact damage
Poor through thickness properties
Variability
Properties not established until manufactured
Limited availability of design data
Reinforcement incorrectly located
Lack of codes and standards
Recycling not easy
Fire, smoke and toxicity performance
Design,
Section 2
Further design Considerations of Composites
– Textured surfaces
– Self coloring
– Integration of parts
– Economy of scale
– Molding direct to final dimensions
– Efficient use of materials
– Durability
– Lifetime costing attractive
Design,
Section 2
Typical aerospace composite manufacturing processes consist of filament winding, fiber
placement, pultrusion, tape laying, tape wrapping, press molding, hand layup and resin
transfer molding.
Uses of Fiber/Matrix
Design,
Section 2
Summary of Composite Manufacturing Processes
Design,
Section 2
Design,
Section 2
PREPREG PRODUCTION PROCESS
Pultrusion
Design,
Section 2
Production Inspection,
Section 2
NDE Techniques for Detecting Defects in Composite Materials
1. Filament winding
2. Fiber placement
3. Pultrusion
4. Tape laying
5. Tape wrapping
6. Press molding
7. Hand layout
8. Resin transfer molding
Detection,
Section 2
Composites tend to fail in a different way to metals
Failure modes
– Brittle fibres in a ductile matrix
– Sudden brittle failure – no elasticity
– Crazing and matrix cracking may occur
– Unseen failure may initiate in the laminate
– Hence fear due to BVID in carbon fiber structures
– Inter laminar disbonding and damage
Detection,
Section 2
This figure illustrates the interrelationship between key factors involved in the concept of
inspection reliability. A detailed discussion in these issues falls outside the scope of this
overall view. Pertinent information can be found elsewhere /1/. However, while some
traditional notions shown may seem self-explanatory for inspection practitioners other,
wide or closely related with the trends of NDT-reliability improvements, deserve to be
outlined.
/1/V. Schmitz, K.J. Langenberg, W. Kappes, M. Kröning: "Inspection procedure assessment using modeling capabilities" Nuclear Engineering and Design,
Detection,
Section 2
With the new developed modeling algorithms, practically the whole NDT testing technique
can be covered. The NDT modeling systems developed under the logo of CAI (Computer
Aided Inspection) are a combination of modeling the geometry and material response of the
inspected component together with the testing techniques and its scanning parameters.
Detection,
Section 2
Accurate NDE methods are considered a necessity to ensure aircraft airworthiness and
passenger safety. Traditionally, tap tests and a few ultrasonic-based inspection methods
have been used to inspect composite aircraft structures.
Detection,
Section 2
Categories of Damage & Defect Considerations for
Primary Composite Aircraft Structures
Detection,
Section 2
A test program, called “Composite Flaw Detection Experiments”, was undertaken
at the Federal Aviation Administration (FAA) Airworthiness Assurance NDI
Validation Center (AANC), operated by Sandia National Laboratories. A large
number of test panels, representing the detrimental conditions of construction
on aircraft, were inspected using a wide array of NDE techniques.
Forty-four Nomex honeycomb core panels with either carbon/epoxy or
fiberglass/epoxy skins were manufactured, with flaws ranging from 0.2 in² to 3
in² (1.29 cm² to 19.35 cm²). F
The panels were shipped to airlines, third-party maintenance depots, aircraft
manufacturers and NDE developer labs around the world. Industry-wide data was
generated to quantify how well current inspection techniques are able to reliably
find flaws in composite honeycomb structure. [Roach, 2010] The program
developed Probability of Detection (PoD) curves for various laminates and NDE
techniques. Results from the “round-robin” detection study are shown.
Detection,
Section 2
The reliability of inspection techniques
may be understood and quantified in
probabilistic terms. Broadly speaking the
inspection reliability is defined as the
probability of not overlooking an existing
defect (probability of detection, POD)
and correct sizing the defect. Whatever
simple this definition may appear, it
encompasses many complex issues
ranging from the specification of the
nature of defects to influencing factors
related with the inspection
instrumentation, product nature, the
involved human factor and the available
expertise for inspection data processing
and assessing.
Detection,
Section 2
Typical reference standard and/or probability of detection sample
Detection,
Section 2
Least opportunity
for detection
Best
opportunity
for detection
Probability of Detection (PoD) versus flaw size (diameter in
inches) for composite sandwich panels with various skin architectures
Detection,
Section 2
Aerospace Damage and Repair Inspection Procedures
• Methods used in the field for aerospace composite
part damage detection, damage characterization, and
post-repair inspection are typically less sophisticated
than those employed by the OEM for their postprocessing inspection. Operators and maintenance
organizations use visual inspection as their main
technique for initial detection of field damages, unless
NDE techniques are specified by the specific
maintenance planning manual or aircraft maintenance
manual. Once damage is detected visually, other NDE
methods are typically used to map the full extent of
damage for proper disposition.
Detection,
Section 2
• In addition to the use of visual inspection to first detect
damage, more sophisticated NDE methods are essential to
the subsequent damage disposition and repair processes.
Many types of damage have both visual and hidden
damages. Hidden damage in composites usually covers a
larger area than visual indications of damage is most
responsible for lost residual strength.
• It is essential that the proper NDE methods be applied to
damage found on aerospace composite structure to map
the full extent of the damage, which is needed to
determine whether damage is below the Allowable
Damage Limit (next slide) or whether repairs are required.
Since a disposition of repair size limits also depends on
accurate mapping, decisions on whether the repair
substantiation database is sufficient also relies on a
complete inspection with the proper NDE.
Production Inspection,
Section 2
We need a general understanding before we begin our inspection!
Are there reference standards?
What is the minimum detectable
vs. minimum rejectable ?
Can the inspection technique detect the
suspected imperfection(s)?
What is the
inspection criteria?
What is the direction
of loading and
suspect flaw location?
What is the best
What is the inspection
inspection
requirement?
method?
What process was used to fabricate?
What type of
defects can be
produced?
Is there a FOE or
FOD program
required?
Customer Requirements?
What are the
qualification and
certification requirements?
What is the Material?
Production Inspection,
Section 2
Testing:
• Component, subcomponent, and generic structural
tests are performed to verify analysis.
• Particular component tests may include elements of
aerodynamics, vibro acoustic and thermal loading
conditions, as well as significant externally applied
mechanical loads.
• Subcomponent tests may be performed for critical
areas of the component.
• Generic tests include flange and stiffened panel tensile
tests, damage tolerance tests, and standard
temperature effect tensile and compressive coupon
tests.
Production Inspection,
Section 2
Production Inspection,
Section 2
Planning the inspection points
Production Inspection,
Section 2
Inspection:
Quality assurance for composite parts centers on techniques for validating the
physical and mechanical properties of a cured composite. However, quality
assurance begins long before the end item is tested. A logical approach to
quality control follows the fundamentals of composite reaction control:
(1) raw material validation reaction control;
(2) material characteristics;
(3) In process fabrication/handling/tooling effects;
(4) cure process control and documentation;
(5) Post cure machining.
Visual inspection is used to inspect bond lines that are visible in the various
bond stages and to detect any visible surface discontinuities and/or
delaminations. Mechanical inspection is used to verify design dimensions,
acoustics, input resistance, static loads and dynamic loads. Nondestructive
evaluation is perhaps the most important inspection technique for
determining defects in composites, particularly the defects specified in Table
Production Inspection,
Section 2
Typical Process Flow
In-Service Inspection,
Section 2
In-Service & Repair Inspection,
Section 2
In-Service & Repair Inspection,
Section 2
REPAIR OPTIONS
When a composite structure sustains damage in service one of three levels of repair
must be employed.
Cosmetic repair
• In this case inspection has determined that the damage has not affected the structural integrity of
the component. A cosmetic repair is carried out to protect and decorate the surface. This will not
involve the use of reinforcing materials.
Temporary or interim repairs
• It is often the case in service, that small areas of damage are detected which in themselves do not
threaten the integrity or mechanical properties of the component as a whole. However if left
unrepaired they may lead to further rapid propagation of the damage through moisture ingress and
fatigue. Simple patch type repairs can be carried out, with the minimum of preparation, to protect
the component until it can be taken out of service for a proper structural repair. Temporary repairs
should be subject to regular inspection.
Structural repair
• If the damage has weakened the structure through fibre fracture, delamination or disbonding the
repair will involve replacement of the damage fibre reinforcement, and core in sandwich structures,
to restore the original mechanical properties. Since a bonded-on repair constitutes a discontinuity of
the original plies, and therefore a stress raiser, structural repair schemes normally require extra plies
to be provided in the repair area. If the damaged area is very small it can be questionable whether a
structural repair, requiring removal of a substantial amount of the structure in damage removal and
preparation, is preferable to a cosmetic repair.
In-Service & Repair Inspection,
Section 2
In-Service & Repair Inspection,
Section 2
In-Service & Repair Inspection,
Section 2
Typical Damage
• Most damage to fiber reinforced composites is a result of low
velocity and sometimes high velocity impact. In metals the energy is
dissipated through elastic and plastic deformations and still retains
a good deal of structural integrity. While in fiber reinforced material
the damage is usually more extensive than that seen on the
surface.
In-Service & Repair Inspection,
Section 2
In-Service & Repair Inspection,
Section 2
Patch repair
• The thickness of the original laminate is made up with filler plies
and the repair materials are bonded to the surface of the laminate.
Advantages
• Quick and simple to do
• Requires minimum preparation
Disadvantages
• A repaired laminate is thicker and heavier than the original
• Very careful surface preparation is needed for good adhesion
In-Service & Repair Inspection,
Section 2
Sample Damage Tolerance Criteria Impact
Nondestructive Inspection,
Section 2
Most Common Production Inspection Method
• Ultrasonic inspection is used to detect flaws in a wide variety
materials, and composites. It can be performed using portable
battery-operated equipment, enabling parts to be inspected while
still installed.
• An ultrasonic testing (UT) instrument typically includes a
pulser/receiver unit and a display device. The pulser/receiver unit
includes a transducer probe which converts an electrical signal into
a high frequency sound wave and then sends that wave into the
structure being tested. A defect in the structure, such as a crack,
will cause a density change in the material and will reflect sound
waves back to the transducer probe. The transducer converts the
received sound waves (vibrations) into an electrical signal which is
then analyzed and shown on the UT display device.
Nondestructive Inspection,
Section 2
Nondestructive Inspection,
Section 2
Nondestructive Inspection,
Section 2
Ultrasonic techniques
Nondestructive Inspection,
Section 2
Ultrasonic techniques
Nondestructive Inspection,
Section 2
Ultrasonic pulse echo technique
Nondestructive Inspection,
Section 2
Ultrasonic pulse echo technique
Nondestructive Inspection,
Section 2
Nondestructive Inspection,
Section 2
Common production inspection
Visual Inspection,
Section 2
• Visual inspection can be a quite powerful and often
under-rated technique for detecting damage in
composite structures. Even low-energy impacts may
leave a slight marring, paint scrape, or faint surface
blemish on a part. A slight wave or ripple on the
surface may indicate an underlying delamination or
disbond. A light spot or "whitish" area on a fiberglass
part may indicate trapped air, a resin-lean or fractured
area, or a delamination.
• Visual inspection is the first line of inspection in both
manufacturing and damage assessment.
Visual Inspection (tap test),
Section 2
Tap Testing
Tap Testing is a quick, inexpensive method for detecting hidden damage. It is especially useful for
finding delaminations and disbonds in thin-skin structures or near the surface of a thick composite part.
Tap testing is probably the most common inspection technique other than visual. By tapping gently on
the surface of a composite part, one can often hear a change in sound from a clear sharp tone to a dull
thud. By tapping back and forth over the area in question, and making a small mark at the point where
the tone just begins to change, it is possible to outline large, irregularly-shaped areas of delaminations
or disbonds. However, there are many limitations to tap testing, including:
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Not good for deep damage.
Requires knowledge of the underlying structural
detail of the part.
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Not very effective in quantifying the degree
or depth of damage.
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Cannot locate very small defects.
Visual Inspection,
Section 2
• Visual inspection is probably the most widely used of all the
nondestructive tests. It is simple, easy to apply, quickly carried out and
usually low in cost. Good eyesight and illumination are required.
Reliability is likely to be improved significantly if undertaken by experts. It
is beneficial if inspectors regularly inspect composite components. No
formal NDT qualifications are required. Visual inspection has the following
advantages and limitations:
doorframe
Cracking of window frame
Visual Inspection,
Section 2
Visual Inspection,
Section 2
Visual Inspection is important, how it is applied is critical!
Inspectors quotes or excuses?: What should be done? What would you do?
1. “…if the inspection needs to be conducted during a particularly
windy evening, I will have to place my cherry picker at a greater
than the normal distance in order to avoid an impact to the
aircraft, which will be moving due to the wind.
However from such a distance I might not be able to detect all
the existing defects.
2. “… if the sun is shining very brightly into my eyes and I am trying
to inspect the rudder I might miss something during that
particular inspection”
Visual Inspection,
Section 2
Visual inspection refers to the simple examination of a component for
defects using the human eye. The term enhanced visual inspection is used
where the inspection is aided by artificial tools, such as closed circuit TV
cameras, special lighting systems, endoscopes and automated defect
recognition tools
Visual inspection is the most common form of inspection for composites and
other materials systems. Increasingly digital cameras, CCTV or video cameras
are used either for monitoring or to provide a permanent record of the
inspection. Visual inspection is widely used for inspection of composite parts,
particularly after manufacture. It is an accepted and useful part of quality
control. There are established standards such as ASTM D 2563 The chief
advantages of visual inspection are its speed, simplicity and ability to detect a
variety of flaws. Coverage may be limited. Speed is usually but not always
faster than NDE methods.
Visual Inspection,
Section 2
Advantages of Visual Inspection
• Simple
• Usually fast
• Widely used
• Accepted standards e.g. ASTM D2563
• Can pick up a range of defects
• Good for obvious manufacturing flaws
• Embedded flaws in GRP can be detected by backlighting
• Does not need NDT qualified inspector
• Can be enhanced by backlighting e.g. GRP chemical vessels
• Can be applied to complex parts where access for NDE is
restricted
Visual Inspection,
Section 2
Limitations of Visual Inspection
• Subjective
• Only see if defects are surface evident
• Lighting conditions critical
• Requires line of sight
• Limited applicability to painted components
• Backlighting not possible for CFRP
• Embedded defects may not be evident, e.g disbonds
• Reliability limited
• Unlikely to be sufficient, unless supported by NDE for
higher integrity components
• Affected by surface condition
Visual Inspection,
Section 2
Hidden damage is the greatest issue, including
manufacturing defects. (for example, a low
velocity impact, which normally wouldn’t cause
much damage may cause a sandwich structure
to disbond between the skin and core due to
poor adhesion during manufacture. If this
disbond is the only damage, there may be no
visible trace of it from the surface.). Reliance on
just visual inspection is not recommended for
higher integrity components.
Visual Inspection,
Section 2
The best quality of visual inspection for transparent/translucent composite
materials is where access is possible from both sides with backlighting. In this
case internal defects such as delaminations, fabrication defects and cracking
may be seen. CFRP composites are not transparent to light. The effectiveness
will depend on wall thickness, resin type and coating. It is increasingly
common practice to paint GRP vessels and pipes for aesthetic reasons, which
makes backlit inspection impracticable. If access is limited to one side then
only surface apparent or obvious defects will be seen. Users often have great
confidence in visual inspection, which belies the limited data available on
actual reliability. Enhanced visual inspection is widely used in airframe
components; here large areas need to be inspected.
Identifiable defects include, delamination, cracks, localised (thickness)
deformation, impact damage, poor wetting of fibres, inclusion, air
entrapments, excessive adhesive in joints (reducing internal diameter),
environmental effects (e.g. UV, erosion) and wear damage.
Visual Inspection,
Section 2
Radome – Bird Strike
Typical Repairs
Inboard Flying Panel – partial separation
Visual Inspection,
Section 2
subsequent inspection – severed spar and skin - aircraft grounded
probable cause – upstream access cover separation/impact
Same defect, visual results, digital radiography and thermographic
Visual Inspection,
Section 2
Know your criteria/nomenclature for inspection reporting per your customer requirements
A dent is a damaged area which is pushed in
or out, with respect to its usual contour.
There is no cross-sectional area change in the
material; edges are smooth.
Flaking is defined as the delamination and possible
loss of the outside ply in a localized area. Flaking
occurs at the part edge or at a cutout, and is caused
by trimming, drilling, or edge impact.
An impact mark is a damage of any size that results
in a cross-sectional area change and
was caused by impact. A mark that was caused by
impact may have additional damage
below the surface of the outside plies. Impact marks
can also occur at an edge.
Examples of visual criteria based on a typical Aerospace Company.
Visual Inspection,
Section 2
Procedures
There are well established procedures and standards for visual inspection of composite
components. The standards also generally include acceptance criteria. This includes:
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ASTM standard D2563 Standard practice for classifying visual defects in glassreinforced plastic laminate parts
Specific procedures are used in different industries dependent on the integrity level
required and the defect types that are likely to impair performance in that type of
composite structure. For example the European Space Agency has it's own
standards for visual inspection of space components.
ASTM standard D 2563 defines critical areas where more stringent criteria may be
required. Four Levels of acceptance are allowed, defined by the user with reference
to the part drawing, dependent on required component integrity. Defects are
categorized in terms of allowable defects and repairable defects. A library of
photographic images is included giving examples of the main defect types.
Visual Inspection,
Section 2
CFRP Structure which effect Maintainability
Visual Inspection,
Section 2
BVID
• Small damages which may not be found during heavy
maintenance general visual inspections using typical
lighting conditions from a distance of five (5) feet
– Typical dent depth – 0.01 to 0.02 inches (OML)
– Dent depth relaxation must be accounted for
Visual Inspection,
Section 2
Criteria Requirements for Visible Damage
• Airframe must support design limit loads without failure.
• No detrimental damage growth during fatigue cycling
representative of the structure’s inspection interval.
– One missed inspection is assumed (two interval requirement)
– Validated by testing
• Airframe must be able to support residual strength loads
until the damage is found and repaired.
Visual Inspection,
Section 2
Sample Damage Tolerance Criteria Impact
Visual Inspection,
Section 2
Sample Damage Tolerance Criteria Impact
Visual Inspection,
Section 2
• CFRP structures must meet same lightning strike
regulatory requirements as Aluminum structures
• Boeing 787 structures are designed, by requirement,
to resist economic levels of lightning strike
Thickness Inspection-Magna-Mike,
Section 2
Hall Effect thickness gages like the Olympus Magna-Mike 8600 are small, lightweight
instruments designed to make fast, accurate, and repeatable measurements of nonmagnetic materials such as plastics, glass, composites, aluminum, and titanium. The first
commercial instruments of this type were introduced in the 1980s and they are now
widely used in a number of industries. Wall thickness is measured by placing a small
steel target (ball, disk, or wire) on one side of the test piece and the magnetic probe on
the opposite side. The Magna-Mike precisely measures the distance between the probe
tip and the target, which corresponds to the thickness of the wall.
Thickness Inspection-Magna-Mike,
Section 2
Hall Effect gages can potentially measure any non-magnetic material whose geometry
permits placing a probe tip on one side of a wall and a small target like a steel ball on the
other, up to a maximum thickness of approximately 1 inch or 25 mm. Materials that can
be measured include all types of plastics and composites, aluminum, titanium, and other
nonferrous metals, glass, wood and paper products, and certain nonmagnetic stainless
steel alloys. Measurement accuracy can be as close as +/- 1% of wall thickness and is
typically +/- 3% or better. Important measurement applications include:
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Plastic bottles and packaging
Molded plastic parts like containers and tanks
Air bag tear seams
Small diameter plastic and nonmagnetic metal tubing
Glass containers and scientific glassware
Aluminum beverage cans
Paper and foam food containers
Machined metal parts (except magnetic steel and iron)
Plywood and particle board
Aerospace parts including turbine blades
2. How Hall Effect gages work
Thickness Inspection-Magna-Mike,
Section 2
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A Hall Effect sensor is a specialized electronic semiconductor which responds to
changes in a magnetic field by varying a voltage that appears across its surface as a
current passes through it. A detailed explanation of the physics behind the Hall
Effect can be found here: en.wikipedia.org/wiki/Hall_Effect. When a Hall Effect
sensor is used for thickness gaging, it is incorporated in a small probe along with a
strong magnet that creates a magnetic field around the sensor. A target such as a
small steel ball bends the magnetic field generated by the probe magnet, with the
bending effect increasing as the target comes closer. As the test piece thickness
and thus the distance between the target and the probe changes, the voltage
across the Hall Effect sensor also varies in a predictable way. Once the instrument
has been calibrated for a particular probe and target, these voltage changes can be
converted to thickness readings through a software algorithm that utilizes an
established calibration curve.
•
It is important to remember that what Hall Effect gages actually measure is the
distance between the probe tip and the target, and thus they measure wall
thickness indirectly. For accurate thickness measurements, the operator must
insure that the probe and the target are properly aligned with each other and
positioned in close contact with the test piece. 3. Probes and targets
Thickness Inspection-Magna-Mike,
Section 2
Calibration: Hall Effect instruments must be calibrated before use, using the same probe and target that
will be employed for measurements. This is done by taking readings with no target, with the target
touching the probe (zero thickness), and at two or more reference thicknesses. This permits the
instrument to generate a calibration table that plots voltage changes versus thickness. The calibration
matches each target being used to an internal lookup table from the unit's memory. The calibration also
measures the two extremes of the target's possible locations (Ball On and Ball Off) and assigns these
endpoints to the lookup table. Additional calibration points at known thicknesses are used to fine-tune
the table for best accuracy. During operation, calibration should be verified whenever probe orientation
or environmental temperature changes.
Probe orientation: Because the Magna-Mike 8600 measures thickness by monitoring small changes in a
magnetic field, its calibration process includes an automatic compensation for the effects of the earth's
magnetic field. Most commonly, the probe is held at a constant orientation, vertically in a stand.
However in cases where the probe is used at a different orientation (such as being held horizontally), or
when the orientation is changing as in scanning the outside of a curved part, calibration must be
updated. In the Magna-Mike 8600, the Q-Cal function is used to make this correction. This is especially
important when measuring near the maximum specified thickness for each target type. Simply remove
the target and press the Q-Cal key while the probe is held at the desired orientation.
FOD Program,
Section 2
Foreign Object Debris and Foreign Object Damage (FOD) Prevention
For
Aviation Maintenance & Manufacturing
FOD Program,
Section 2
Foreign Object Debris (FOD) often causes Foreign Object Damage (FOD). The
majority of instances of FOD can be attributed to lack of standards in an
organization, personal complacency or disregard for procedures.
These may also lead to additional sources of FOD caused by
• insufficient housekeeping, training or controls
• deterioration of facilities
• improper tools and equipment
• improper or careless maintenance or assembly
• fatigue and scheduling pressures.
Foreign Object Debris (FOD) can come in many different forms and may
produce disastrous effects if not identified and corrected. In severe cases,
FOD can directly threaten safety of flight crews and integrity of the aircraft.
FOD Program,
Section 2
In composites manufacturing, FO is anything e.g. tape, backing material, peel ply,
bagging material, etc. utilized in the process that was not intended to be included in
the finished part. Material unintended to be in the laminate or bonded assembly may
have adverse effects!
•
•
•
•
Foreign Object (FO) or Foreign Object Debris (FOD) – A substance, debris or article
alien to an aircraft or system, which would potentially cause damage.
Foreign Object Damage (FOD) - Any damage or malfunction attributed to a foreign
object that can be expressed in physical or economic terms which may or may not
degrade the product’s required safety and/or performance characteristics
Critical FO: Foreign objects inadvertently left in areas inside of a component or
aircraft from which migration is possible, e.g. through tooling holes, bend relief
cutouts, drain holes, intakes, etc., which are probable to cause system or
component malfunction or deterioration should the product be put into use.
Foreign Object Elimination (FOE): a program or process used to assure a FOD-free
product/system.
FOD Program,
Section 2
Clean-As-You-Go:
• Clean the immediate area when work cannot continue.
• Clean the immediate area when work debris has the
potential to migrate to an out of sight or inaccessible
area and cause damage and/or give the appearance of
poor workmanship.
• Clean the immediate area after work is completed and
prior to inspection.
• Clean at the end of each shift.
• If you drop something or hear something drop - pick it
up!
FOD Programs,
Section 2
Six Sigma: A comprehensive and proven set of tools and techniques applied in a consistent, systemic
fashion to enable to better solve problems and optimize processes in all functional areas. The main focal
points of Six Sigma are:
• Waste Elimination primarily through Lean principles and tools,
• Variation Reduction through traditional DMAIC tools (Define, Measure, Analyze, Improve, Control),
and
• Growth and Innovation using the tools and principles of DFSS (Design for Six Sigma).
Lean Manufacturing: Lean manufacturing is the production of goods using less of everything compared
to mass production: less human effort, less manufacturing space, less investment in tools, and less
engineering time to develop a new product.
5S: The Japanese mnemonic based process for housekeeping and organizing for efficiency. 5S is a
philosophy and a way of organizing and managing the workspace by eliminating waste.
•
•
•
•
•
•
Sort
Straighten
Shine
Standardize
Sustain
Some organizations use 6S with the 6th S being Safety.
Composite Quality Assurance,
Section 2
Aircraft Programs, OEM’s, Suppliers as well as the individuals
who fly every day depend on Quality Assurance Programs

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