NDI equipment

8/12/2019 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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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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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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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)


(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




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Part name

Dimensions

(LXW) (Meters)



(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


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


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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(LXW) (Meters)



(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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(LXW)

(Meters)



(Mins)

Model

LONGERON INBOARD-LH 3.828X0.195 47

SPLICE-WEB-SPAR-FRONT 0.688X0.532 42



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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

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