Pre-to-Post Use Evaluation using Industrial CT Scanning

High Resolution part evaluation

Industrial CT Scanning is used to characterize a variety of products including multi-material plastic assemblies like this wall anchor.

Some practical uses include:

> Fitment analysis - clearance & interference

>> Dimensional inspection - concentricity & wall thickness

>>> Porosity, inclusion, and fiber orientation evaluation

>>>> Pre-to-Post Use Comparison

Pre-to-Post Use Evaluation

Pre-to-Post use evaluation is particularly useful for understanding how a part changes over time. For example, in the below comparison slider we can see the threads created from a screw. We can measure the wall thickness where the expansion wings bend. We can also see how the the interface between the two components changes. Lastly, we can measure damage caused by insertion and removal.

Anchoer Close 1 Anchor Close 2

CT Scan of Shaver – Blade Wear Analysis

Evaluating an Electric Shaver

Industrial CT scanning can be used to investigate components and assemblies for proper part placement, failure analysis, and wear. This Norelco shaver is a great demonstration sample because of how complex it is:

  • Multiple materials including plastic & metal
  • Intricate gears & interfaces
  • Small features like sharp blades
  • Motor with copper winding
  • Rechargeable cylindrical battery
General 2
gENERAL 1

Blade wear comparison

New and used blades were scanned at higher resolution to understand how the part changes and becomes less effective over time. First, the blades were aligned on top of each other for a direct visual comparison.

The top view shows a cylindrical unroll of the blade. This allows us to simultaneously view all nine blades. From this view we can hypothesize that the lower performance of the used blade is caused by the blades being bent downward over time.

NEW
USED

measuring the hypothesis

By exporting the blades into .STL scan file format we can use PolyWorks dimensional software to produce a part to part profile comparison. This map confirms that most of the blades are approximately 50 microns lower than the new blade.

CROSS SECTION COMPARISON

A 2D cross-section is placed across “best-fit” aligned blades. The used blade was then manually shifted to the left to help visualize the samples. Then, arcs were defined on each blade with an approximate deviation of .006mm between nominal (new blade) to measured (used blade.)

CT Imaging NASA J2 Engine Thrust Chamber Cooling Channels

CT Imaging the Brazed Tubing of Saturn V J-2 engine Thrust Chamber

Per Wikipedia the J-2, commonly known as Rocketdyne J-2, was a liquid-fuel cryogenic rocket engine used on NASA’s Saturn IB and Saturn V launch vehicles.

The J-2’s thrust chamber assembly served as a mount for all engine components, and was composed of the thrust chamber body, injector and dome assembly, gimbal bearing assembly, and augmented spark igniter. The bell-shaped chamber was regeneratively cooled by the cryogenic fuel flowing through these tubes. The brazed tubes are aligned then melted together to form the chamber and bell which was tricky, expensive to manufacture, and prone to defective end results.

j-2-thrust-chamber-assembly-sm
j-2-thrust-chamber-detail-sm

The above chamber section was CT scanned (thousands of 2D x-rays about a 360 degree axis) at 225kv. The x-ray dataset was then processed into a 3D file, called a volume, where we scroll through and inspect the sample digitally. If only the engineers responsible for putting astronauts on the moon had the ability to inspect mission critical welds and joints in this way! Below we are able to characterize porosity, penetration percentage, wall thickness, and more.

Loc 1
Loc 2
Loc 3
Loc 4
Loc 5
Loc 6

Investigating Packaging Leaks using Industrial CT Scanning

PACKAGING inspection using INDUSTRIAL CT SCANNING

We regularly inspect packaging for a variety of goods using industrial radiography and CT scanning. Typical inspections include component presence verification, wall thickness evaluation, and leak path detection. This case study looks at a leaking boxed wine dispenser.

The dispenser itself is very interesting. The image below shows the functional sequence.

  • 1
    PRESS RUBBER BUTTON
  • 2
    BUTTON TRAVELS UP RAMP
  • 3
    RAISED BUTTON LIFTS RUBBER SEAL & COMPRESSES W-SHAPED SPRING
  • 4
    UPON RELEASE, W-SHAPED SPRING FORCES SEAL BACK TO CLOSED POSITION

Investigating Leak Point of Origin

  • 1
    PLASTIC BAG SEAL - BAG TO DISPENSER BONDED TOGETHER
  • 2
    CARDBOARD PACKAGING
  • 3
    UNROLL VIEWING LOCATION - USEFUL FOR VIEWING A CYLINDRICAL FEATURE IN A PLANAR VIEW
  • 4
    UNROLL VIEW - LEAK PATH - DEFECT OF INTEREST LOCATED

FOD & Potting Failure in Probe

INVESTIGATION OF PROBE FAILURE

During testing it was found that this probe was the culprit of a larger article’s performance failure. We CT scanned the unit to produce a full characterization of the part. A variety of indications were located in the scan:

> Foreign Object Debris (FOD)

>> Linear indications and pathways in the potting

>>> Porosity and gas holes in the solder pads

INDICATIONS VISUALIZED

The yellow arrows below point out the indications like FOD and potting pathways. The pathway travels the full length of the potting.

The below images show the porosity and gas holes in the joints, as well as large holes in the potting.

Inspecting Surgical Screws using Industrial CT Scanning

CT SCANNING IMPLANT SCREWS FOR INSPECTION & REVERSE ENGINEERING

Microfocus CT scanning is used to produce high resolution, water tight scan files of implant screws for a variety of reasons including:

  • Non-destructive evaluation – ensuring products are free of contaminants and flaws like cracks
  • Dimensional evaluation – ensuring products meet design specifications like profile and concentricity
  • Reverse engineering – manufacturers may need accurate models of products to design their own geometry
Surgical Screw CT Scan 1
Surgical Screw CT Scan 2

CT SCANNING FOR REVERSE ENGINEERING

The sample to the left has been reverse engineered to a toolable .STEP model. The screw was CT scanned, exported to .STL, and then modeled in Geomagic Design X.

Demonstrating CT Scan Parameter Affects on Quality

Demonstrating Scan Parameter Quality Differences

This case study seeks to demonstrate CT scan parameters and their effects on data quality. The data focuses on quantity of projections and frame averaging. All parameters remained constant except for a single 20um scan.

The test sample is a standard button battery which is more complex than it looks with its high density can and low density, fine-featured anode and cathode materials.

PRIMARY CT SCAN PARAMETERS

> Geometric Magnification (Voxel Resolution)

Geometric magnification is defined as the ratio of a test specimen between the x-ray source and detector. If the detector is stationary and the part is moved toward the x-ray source, magnificaiton increases but the field of view decreases. This principle is the most important factor for achieveing high resolution scans. 

>> Quantity of X-Ray Projections and Frame Averaging

Circular CT scanning produces a cylinder of 3D data. This cylinder is, effectively, a subdivision of x-rays about its axis. The more the cylinder is subdivided (# of projections) the more rich the dataset becomes. Additionally, noise can be reduced by duplicating each projection (frame averaging). There are significant diminishing returns when optimizing these settings.

>>> Electronic Parameters (kV, Wattage, Exposure, Gain)

Electronic parameters significantly impact scan quality. Wattage, or focal spot size, can reduce effective resolution by defocusing the data. Not enough penetrating power (kV) could eliminate the ability to characterize features. High gain brightens an image but does not add meaningful contrast.

>>>> Physical Parameters (Filtration, Part Orientation)

Physical parameters are used to improve data quality. Source side filtration absorbs low energy x-rays, reducing artifacts like scatter. Part orientation is determined on a per-project basis. If an area of interest is specified, staging that area away from other features improves x-ray penetration.

BEST VERSUS WORST QUALITY

(hover to view)

BEST VERSUS WORST QUALITY

Touch the image to see the best quality scan.

FRAME AVERAGING COMPARISONS

The below tabs demonstrate the quality differences of quantity of projections and frame averaging; all other variables remained constant except the 20um scan. There is a significant difference between even a standard scan and the highest quality. However, this difference must be factored against scan and processing time. Is the highest possible quality necessary for what for what is needing to be learned from the test sample? If it’s not, and there is a large lot of samples to be scanned, optimization of the scan parameters could save significant cost and precious time.

FRAME AVERAGING COMPARISONS

The below tabs demonstrate the quality differences of quantity of projections and frame averaging; all other parameters remained constant. There is a significant difference between even a standard scan and the highest quality. However, this difference must be factored against scan and processing time. Is the highest possible quality necessary for what for what is needing to be learned from the test sample? If it’s not, and there is a large lot of samples to be scanned, optimization of the scan parameters could save significant cost and precious time.

The content below is best viewed on desktop with 3x as many examples.