ndi equipment
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Ultrasonic inspection technology
Pulse Echo
transducer sends out a pulse of energy, to normal of surface . The pulse is reflected from good matrix
reinforcement boundaries, and boundaries associated with flaws,
The position of flaw and size of flaw is determined by the total pulse travel time and detected amplitude
Through Transmission
Reflections occur due to the presence of discontinuities and the surfaces of the test article.
Reciver being placed on the opposite side of the component and facing the transmission probe.
Compared to pulse echo there is no dead zone which means that flaw can be detected at all depth through the
thickness of the part.
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NDI inspection methodologies (In house) and defect identification
Inspection Techniques Type of identifiable defects
Visual Inspection Delaminations over skin surfaces, Porosity (Visible), Visible inclusions,
Tap test interply delaminations, skin-to-honeycomb disbonds (near side of non metallic
cores),
A scan Fiber Breakout from Drilling Operations (Drilling, Counter sinking), Surface
Depressions, Defects in corners and radius,
C scan-Squitter Surface Scratches, Surface Depressions on Bag side and Tool side, SurfaceResin Ridges, Tedlar Wrinkles, Bondable Teflon Wrinkles, Missing, ResinRich
Areas, Core Edge Depressions, Part War page, Honeycomb Core Node Bond
Separation, Radius Bridging, Surface Resin, Foreign Material Detected by NDI,
Surface Resin Starvation, Internal voids, PorosityC- Scan - Bubbler
Infrared Thickness variation in parts, delaminations, Disbonds sandwich (Metallic cores),
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NDI Techniques and their selection criteria
The major factors deciding selection of NDI inspections are
Engineering Drawing/Manufacturing standards
Machine parameters and capacities
Part sizes
Part types
Part profile complexities
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NDI Techniques (In house) and their selection criteria
The different factors for selecting NDI inspection for a part are listed below
1. Engineering drawing/ manufacturing process requirement
Engineering drawing call out usually specifies NDI requirement for part
When part drawing/Manufacturing document calls for below classes
BOEING
Example 1:BAC 5317
Class AVisual inspection and instrumental NDIFirst cure of each production part
Visual inspection and instrumental NDIeach detail part and bond line after respective cures
Class BVisual inspection and instrumental NDI at designated locations in the Engineering drawing as per Boeing approved plan
Class CVisual inspection and instrumental NDI for each production part according to the sampling plan approved by Boeing
Class D Visual inspection of the production part
* When no class is specified part should be inspected as per Class A
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NDI Techniques - selection criteria
1. Engineering drawing/ manufacturing process requirement
Example 2: BAC 5578
TYPES
Type IRequires: (a) Visual and (b) dimensional inspection of each production part.
Type IIRequires: (a) Type I inspection and (b) instrumental NDI based on a sampling frequency equivalent to MILSTD1235 with an
Average Outgoing Quality Limit (AOQL) of no greater than 1.
Type IIIRequires: (a) Type I inspection and (b) instrumental NDI at locations designated on the Engineering drawing using a sampling
frequency in accordance with Type II.
Type IVRequires: (a) Type I inspection and (b) instrumental NDI on each production part.
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NDI Techniques (In house) and their selection criteria-
C SCAN SQUITTER
2. Machine parameters-
Machine operating parameters
Length 6.5 m
Width 2.0 m
Height 2.5 m
Inspection speed 1.67 m/s
Max. linear acceleration 1.5 m/s
No of axes (X,Y,Z,A,B) 10
3D rotation/Limitation angles A= +105to -105
B= +180to -180
Transmission medium (Coupler) Water
Mode of inspection Pulse echo and Through transmission
Existing inspection- Through transmission
Range of parts can be inspected Monolithic parts, sandwich parts, metallic (Skins),
Ceramic skins e.t.c
Complexity Flat, Semi curved, C shaped, S shaped, T shaped
Geometries can be inspected Part surface
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NDI Techniques (In house) and their selection criteria
Importance of part bunching in squitter Time study
Case 1
Scanning of single part - FACC part number FK13798
L=1.1M W=0.65M
1. A single part FK 13789 was given to squitter for scanning
2. Machine was ruuned at 60 % of maximum speed.
3. The overall scanning time for the above mentioned part was
51 Minutes.
Reason
Before attaining the maximum acceleration of the machine
(Which is supposed to be attained at 6.5 m) the
machine is decelerated immediately after scanning
the part Width of = 0.65m
Since the maximum speed of the machine is not utilized the overall
inspection time is more.
Fig:2 Comment of the inspector in the inspection report
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NDI Techniques (In house) and their selection criteria
Importance of part bunching in squitter Time study
Case 2
Scanning of four partsbunched - FACC part number FK13798
1. Four FK13798 parts were bunched together in the fixture
2. Machine ruuned at 60 % of maximum speed
3. The overall inspection time for the machine was 63 mins
Reason
In this case machine was ruuned at 60% of maximum speed
Scanning length of the machine was 2.6m (Total width of 4 parts)
Even though maximum speed of the machine speed is not utilized
The total scanning time for 4 parts was less compared to scanning a single part.
This study shows the importance of utilizing the maximum scanning length of the machine
Fig:3 Comment of the inspector in the inspection report
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NDI Techniques (In house) and their selection criteria
Fixture Study
The present fixture in Water jet using for programs excluding Boeing program is below
Usable dimensions Length=6.2 m
Width = 2.3 m
Figure shows spirit- lower panels of 3 different sizes bunched in the fixture.
Presently parts are scanned as per ship set requirement and plan
Parts having same ref stds are bunched together.
Almost 80 percentage of the fixture length is used in this bunching plan.
Suitable orientation of the part in fixture also plays a major role in
reducing overall inspection time
Concept of Lower panels bunched in existing fixture.
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Scanning Times for Existing programs
Inspection timings for spirit parts in squitter
Part name Dimensions
(LXW) (Meters)
Total Inspection time
(Setup time + M/C Time)
(Mins)
Model
Panel 1 inbd 1.43x1.004 60
Panel 3 inbd 1.613X0.764 53
Panel 4 inbd 1.795X0.495 60
Panel 5 inbd 1.77X0.435 57
Panel 6 inbd 1.667X0.415 53
Panel 7 inbd 1.346X0.376 52
Dimensions courtesy: EstimationTimings Courtesy: SAP
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Part name
Dimensions
(LXW) (Meters)
Total Inspection time
(Setup time + M/C
Time)
(Mins)
Model
Panel 1 outbd
(Monolithic)
1.032X0.223 38
Panel 1 mid outbd
(Monolithic)
01.825X0.51 53
Panel 3 outbd1
(Monolithic)
0.418X0.117 20
Blow down Panel 1 0.372X0.233 24 NA
Blow down Panel 2 0.367X0.233 24
Blow down Panel 3 0.422X0.218 24 NA
Dimensions courtesy: Estimation
Timings Courtesy: SAP
Inspection timings for spirit parts in squitter
Scanning Times for Existing programs
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Scanning Times for Existing programs
Inspection timings for spirit parts in squitter
Part name
Dimensions
(LXW) (Meters)
Total Inspection time
(Setup time + M/C Time)
(Mins)
Model
148A7406-7 60
148A7406-8 60
148A7406-10 60
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Limitations and advantages of C scan Squitter
1. Parts having different ref stds cannot be bunched and inspected
2. Machines maximum speed cannot be utilized, because the generated graphics will be having
discrepancies and distortions
3. Local areas where parts clamped are to be scanned again in A scan machine4. Inspection of holes less accurate and need to be inspected in A scan
Limitations- C scan Squitter
Advantages - C-scan Squitter
1. High repetitive accuracy due to stable design.
2. High accessibility due to slim construction of inspection mechanics (e.g., U-shapes, aircraft
structural parts and exterior panels).
3. Product-specific inspection area due to modular construction.
4. Corrosion resistance
5. Collision protection
6. Automatic water control - adaptation to inspection head position.
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Machine parameters- C-scan Bubbler
Machine operating parameters
Length 6 m
Width 1 m
Max thickness inspecting presently 22 mm
Inspection speed Currently running at 70% of max speedSpeed isdetermined based on trial and error method(Clarity of image generated)
No of axes (X,Y,Z)
Transmission medium (Coupler) Water
Mode of inspection Pulse echo and Through transmission
Existing inspection- Pulse echo
Range of parts can be inspected Monolithic parts, sandwich parts, metallic (Skins)
Complexity Flat, T shaped, C shaped, L shape
Geometries can be inspected Part surface
NDI Techniques (In house) and their selection criteria
C SCAN BUBBLER
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General inspection methodology (NADCAP requirement)
STEP 1: Inspection of reference standard
STEP 2:Inspection of part
STEP3: Re inspection of reference standard
NDI Techniques (In house) and their selection criteria
REFERENCE STANDARD
Scan 1, Scan 4 PART 1- Scan 2 PART 2-Scan 3
6.0 M
1.0 M
Usable Dimensions of C scan bubbler
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Scanning Times for Existing programs
Part name Dimensions
(LXW) (Meters)
Total Inspection time
(Setup time + M/C Time)
(Mins)
Model
STIFFNER-SPAR-HORIZ-UPPER-
INBD0.376X0.288 20
TEE-SPLICE-UPPER-BUILD DOOR 1.32X0.253 50
STIFFENER UPR HORIZ 5.737X0.331 172
STIFF-SPAR-HORIZ-LWR 5.736X0.326 172
SPLICE-ANGLE-SPAR-FRONT-
LOWER FLAT0.587X0.216 42
SPLICE-ANGLE-SPAR-FRONT-
LOWER KINK0.647X0.248 32
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Part name Dimensions
(LXW)
(Meters)
Total Inspection time
(Setup time + M/C Time)
(Mins)
Model
LONGERON INBOARD-LH 3.828X0.195 47
SPLICE-WEB-SPAR-FRONT 0.688X0.532 42
Scanning Times for Existing programs
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Limitations and advantages of C scan Bubbler
Low inspection speed
Two times Inspection of ref. STD irrespective of part (NADCAP) requirement
Re inspection of part in A scan for part hole and radius and un identifiable defects
Maximum part size which can be inspected in existing fixture is 6.0 MX 1.0M, So part bunching is
limited
Limitations in scanning sandwich parts
Machine can inspect a part of Length 600MM Width 1,000M______thickness ____ MM, With present capacity
Limitations- C scan Bubbler
Advantages - C-scan Bubbler
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General notes