Apr 16

International CT scans

This case study is meant to explain that our CT scan services are international – there is no need to be here on location for scanning and shipping most typical samples are no problem at all. The advantage? The price! The price of CT scans is much lower here than in your local CT service lab. So to make a case study of this we scanned a South African 2 Rand coin and a 2 Euro coin, as well as my credit card. All images here are from CT scans – and imaged using VGSTUDIO MAX 3.2. No coins or credit cards where harmed in the making of this case study (totally non-destructive process).

First up – the Euro (video here – Euro video):

Now for the South African Rand (video here 2 Rand):

Now, we take apart the Euro (video here euro take apart):

For viewing the Euro and Rand side by side – see this video  Euro and Rand

Comparing the Rand to the Euro – clearly the Euro is thicker:

And overlapping them – it seems there are mostly major deviations between Euro and Rand.

So can you pay by credit card? yes you can. Here is an example of a X-ray of a credit card with chip (and small crack in plastic):

Also see the CT scan of the chip in this video and image below: credit Card Chip Wall Thickness

 

We hope you enjoyed this case study. On a more serious note – if you know microCT scanning and want to send us your parts you are welcome – we offer international CT scan and analysis services on hourly rates of $165 (US). If you are unsure please see the “make an order” tab or contact us to make you a quote. For international shipments, please add clearly to the package “for testing only – nominal value $1” to ensure no delays and simplify the process, and please use dedicated courier services (e.g. DHL), not postal services.

Apr 10

CT scanning of cast metal parts

This is one of the best-known applications of X-ray inspection and CT scanning – to check cast metal parts for porosity and extent of porosity. Here one example with nice video showing the data and results available for such parts.

CLICK HERE FOR A VIDEO OF CT RESULTS: casting1_small

Mar 18

X-ray CT inspection for medical implants

Introduction

This case study was performed to demonstrate how routine X-ray CT inspection adds value to medical implant production, ensuring quality and reliability. This particular case is for 3D printed (additively manufactured) titanium hip and knee implants but the methodology is applicable to all manufacturing techniques, not only additively manufactured implants.

X-ray CT inspection is relatively expensive compared to older inspection methods, but is significantly better as it allows entirely new insights and streamlined workflows, saving costs long-term and providing higher reliability in inspections – which is ultimately better for the patient. This case study aims to show that the costs are not excessive, and is based on current costs for CT inspection services at the Stellenbosch CT facility, which is a relatively low-cost service facility compared to international X-ray CT inspection services. This is an example of a relatively routine inspection – for special cases such as higher resolution requirements, denser metals, or specialized scan parameters, the costs can be higher. In some cases costs can be lowered for simpler inspections, simple samples and easy-to-detect features. This case study is a typical workflow and a good indication of costs – especially for new users of the technology.

Implant samples

Two samples were provided by Executive Engineering (www.execeng.co.za), who produce these parts under contract for LRS implants (https://www.lrsimplants.com/). Both these companies gave approval for the release of this case study. Executive Engineering is a local company on the outskirts of Cape Town which has a newly established metal additive manufacturing facility, with an EOS M290 currently running only Ti6Al4V. LRS implants specialize in design and production of custom medical implants.

The two parts are biomedical titanium alloy Ti6Al4V (ELI) material and are parts of hip and knee joint implants. They are shown in Figure 1. Lattice regions are included to improve long term bone-in-growth and attachment. Both parts were scanned at typical parameters used for this material, at resolution defined by the sample size. For more on scan parameters and optimization, please refer to the references or contact us for more information.

Figure 1: The implants – photograph with magazine for scale and 3D X-ray CT images

 

What results do we get?

X-ray CT is a technique that has many capabilities – it can be used for many things. Obviously when you want to do everything – it costs the most. We break it down into different levels, you might only want one of these, but we demo everything here. The first level, which could be called manual CT inspection, is the simplest and lowest cost. This involves simply checking the part in virtual cross section images (called CT slice images). After scanning and basic data handling, the inspection is done by viewing cross-sectional images. This can be done by the user himself, requires no complex software tools and easily and clearly visualizes even small internal flaws which might be problematic. An even simpler way to do this is to view a slice video, see here for videos of both implants – also shown in Figure 2 in different slice views of both implants. In these images, everything in the white line (all white and grey areas) is metal, and black is air. In this part no unexpected cracks or flaws were found. For examples of porosity, cracks or flaws please see this case study of a few years back – for a cast metal part. Major flaws would be in the form of dark black areas and lines in the white material, which are not present here.

Figure 2: CT slice images showing no internal flaws – the inserts show the location of the virtual slice

 

Video of all slices from top to bottom – implant 1: slice video implant1 HD

 

Video of all slices from top to bottom – implant 2: slice video implant2 HD

 

Manual inspection requires a scan of high quality, and basic data handling to generate clear well-contrasted slice images. Usually we the CT service provider highlights “indications” – areas of potential flaws. This can also be handled by the customer himself, either with slice image stacks, video or full data with free 3D viewer program. This program is called Volume Graphics myVGL and is freely available for all data handled by Volume Graphics VGSTUDIO MAX 3.2, which is also the software used for this case study. Videos on how to use this is available here. For the scan + basic data handling, the cost is R2900 (international rate US$330). This provides clear insight into the presence of flaws and is suitable for all parts (as the method is entirely non-destructive) or can be applied to selected samples from batches produced under identical conditions. This price is applicable to decent quality scans without special requirements, i.e. it is for typical implants of light metals, in the range roughly 50 – 150 mm in longest axis. Smaller or larger samples might require some variation of scan protocols which adds to the cost.

Besides using this method for checking to ensure all parts are flawless (and reject those that aren’t), it is also possible to use the method for calibration of systems and production process checking – using smaller test parts. This provides a fixed, documented result of the same test geometry analyzed the same way over time. This allows insight into the production quality and any progressive quality issues developing over a longer term. This is a topic which is highly applicable to all forms of manufacturing, but is especially useful for additive manufacturing where many factors can affect the quality of the final product.

A quantitative defect analysis function allows colour coding of pores inside the part, when this is found. This is an extra R1450 (international $165), but in this case no such flaws where found. This method is particularly useful when testing small coupon samples for optimizing the production process, ie. when improper settings cause some porosity or flaws. The advantage of a quantitative 3D colour coding of defects is the ability to understand the 3D shape and distribution of the flaws relative to the part features (e.g. near critical areas, or showing what the cause of the problem is, to more easily and faster fix this problem).

For this case study, the next level of insight is the use of the same scan data for metrology – that means accurate dimensional measurement, often done traditionally with coordinate measurement machines (CMMs). The accurate surface determination allows various selected dimensional measurements such as diameter of critical cylindrical cavities shown for the part in Figure 3. In addition the STL file data can be exported, or preset dimensional analysis can be performed on batches of parts with accept/reject criteria. For typical CMM measurements of up to 10 features, the additional cost is R1450 ($165 international). For batches of similar parts more measurements can be preset and run automatically for the same price.

Figure 3: X-ray CT is also a coordinate measurement machine, without limits on complex geometry or accessible points

The next level, also costing the same (R1450 or international clients $165), is comparing the actual produced part with its CAD design file, to see where large deviations occur. The implant is shown in Figure 4, with most of the part within 0.3 mm. The scan resolution here was 65 µm – and with good scan data up to 1/10th the voxel resolution can be used as the accuracy of the surface values. This means the surface data is likely 6.5 µm accurate, without any limits on hidden or complex features, or limits on surface finish which are sometimes issues with CMMs.

Figure 4: CAD variance analysis – showing most of the part is within 0.3 mm of the design file.

A useful additional tool is wall thickness analysis (you guessed it – additional R1450 or $165) – this method shows the thickness of walls of the part, mostly used for checking traditionally designed parts with parallel walls. It can also be used to visualize and check the thickness of very thin and complex areas such as lattice structures, as shown in Figure 5. Here most of the lattice is within 0.2-0.5 mm thick. The method used here is the sphere-method – the largest sphere that fits in the material at each point is reported as the wall thickness at that location.

Figure 5: Wall thickness analysis applied to lattice areas showing local thickness of struts

 

So what are the limits and how to overcome them?

As with all methods, there are some limits. When materials unexpectedly contain high levels of dense inclusions or materials containing X-ray dense materials, this causes unwanted image streaks which make some analysis methods impossible. Often the presence of steel screws in parts with lighter metals have the same effect. Sample size is limited, and this is especially important when looking for small flaws – i.e. when there is a small flaw or crack and the resolution is not good enough, these may be missed. These and many other possible issues may lead to failed or inconclusive results. Some key points to ensure high quality CT inspections:

  • Smaller samples provide better quality and resolution
  • Scanning two or more parts at once provides worse quality and resolution
  • Remove all screws or unnecessary material from the object of interest
  • Understand the limits and the capabilities to get the most from the technique

 

Summary

Clearly X-ray CT inspection is a powerful tool for entirely non-destructive inspection of medical implants. We have demonstrated here the following levels of inspection, which are possible:

Description Cost

* Excludes 7% admin fee and VAT

1 Manual CT slice inspection R2900 / $330
2 Defect analysis (quantitative) +R1450 / $165 (optional)
3 Coordinate measurements +R1450 / $165 (optional)
4 CAD variance +R1450 / $165 (optional)
5 Wall thickness +R1450 / $165 (optional)

 

This means that for one part, for an all-inclusive analysis of everything possible, it costs less than R10 000*. While this is more than traditional nondestructive testing (NDT) tools, the clarity and quantitative assessment allows to really improve the lives of patients, to clearly identify when even small flaws or manufacturing errors are found in parts. On the other hand, even the first-level of analysis is useful for this purpose, bringing the cost down by almost 70%. Further cost reduction might be in optimizing and calibrating the production process itself using CT on a regular basis and not inspecting all parts produced. Any way you look at it, the insight into implants with 3D X-rays is clearly value for money. If you are not yet convinced, have a look at this video which summarizes all the above: medical implant scan small_version

 

This case study was made possible with cooperation from Executive Engineering & LRS implants. Scans were performed at Stellenbosch CT facility and visualization and analysis performed with VGSTUDIO MAX 3.2.

 

Feb 07

What is inside a Samsung S7 smartphone?

This case study is a quick but powerful demo of what X-ray CT inspection can do. The Samsung S7 used in the test is my own phone, 2 years old and not in use. This phone was released about the same time as the Samsung Galaxy Note 7 – which had battery explosions often. The S7 was also known to overheat (my own experience also), so let’s see what’s going on inside this phone.

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The top-view cross section of the battery shows its layers tightly wound up – the edges seem to be “compressed” into the tight-fitting space (top right for example). Seems like too much material for too small space, but no short circuits or flaws directly seen here.

The only flaw found in this phone was a small indentation on the battery, behind the antenna (black stripe):

3D visuals helps to understand connectivity and orientation of different parts, for example this image shows some sections highlighted:

The following video shows the entire phone in 3D views of various internal sections, including inspection of electronics soldering pads – these always have some voids (air spaces) but they should not be too big, this one passes:

samsung vid3

If you want to make a non-destructive test of your product, or want to apply this test to your research topic – contact us. This case study used an quick overview scan and a detailed high-resolution scan overlapped. Analysis by VGSTUDIO MAX 3.2.

Jan 17

Bike frame scanning

Here is a video of a recent scan, watch this space for more info!

bike NDT small video

Nov 01

View from the inside

This is a microCT image of the inside of a 3D printed metal lattice structure – the struts are 0.75 mm wide and rough as built by laser melting of metal powder.

Nov 01

Fully booked for 2018

Sorry but we are fully booked for the rest of 2018. We can still do surface scanning with our Artec scanners, and we can make image analysis or you can book for your own image analysis sessions, but scanning is not possible this year anymore.

If you have a super critical scan to be done, please contact us and we can make after hours scanning, if you drop off your sample.

For normal work, please book for 2019

Jan 25

New developments for 2018

With a new year comes new exciting capabilities and possibilities for our users. We have the following new additions to the facility, all becoming fully available on 1 Feb:

  1. New scanners: Artec Eva and Spider

Artec Eva and Spider are two scanners meant for 3D scanning of any objects to generate accurate surface models, including photorealistic texture. For more information on these scanners please see the Artec website:

Some ways you can use them for your R&D:

  • measure your fruit still growing on the plant, once a week, to check real growth and volume change
  • measure actual dimensions of large metal parts that are difficult for CT scans, to compare to design files
  • reverse engineer a complex part that is broken
  • scan objects and overlap 3D textured mesh with CT data of same object, for great visuals
  • scan weld seams to check for surface problems
  • scan your head to make a 3D print of yourself
  • and so much more!

2. Do your own scans

Many researchers and students want to do their own scanning, this is now possible, conditions are:

  • training charged at full rates for 8 hrs, one student per training only
  • student must pass a basic proficiency test after the training, or repeat the training
  • self-scanning is limited to fixed parameters set up prior to session
  • fixed after hours scan rate per evening session, irrespective of machine problems that might come up
  • currently only on nanoCT (samples smaller than approx 25 mm)

3. Make your own quotes online

  • system almost ready: starting 1 Feb
  • check the price for a scan, without any hassles
  • find a scan quality and service combination that fits your pocket
  • book your scans without any delays, any time of day!

Nov 10

Step by step microCT scan process

Here are some photos of a typical scan process, in photo steps:

Step 1: Load the sample in some low density mounting material – the sample is a concrete of undisclosed origin, and the project will not be discussed here
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Step 2: load the sample into a rod or cylinder

Step 3: open the machine door

Step 4: load the mounted sample into the rotation stage of the machine


Step 5: Put in appropriate beam filter (that means a metal plate)

Step 6: Set up appropriate scan parameters (which might need some optimization per application)

Step 7: Start scanning

The next steps after scanning will be the focus of another day’s demo:

Step 8: Reconstruct the data

Step 9: Analyze the data – we use Volume Graphics

Step 10: Save the images, reports, raw data and copy to disk (we dont keep data here)

There is also a video on youtube: https://youtu.be/Yqui4OPVZu0
https://youtu.be/Yqui4OPVZu0

Aug 03

Metal casting analysis

Metal castings typically contain porosity which can affect the strength and lifetime of the part. Excessive porosity can be reduced by optimizing the casting parameters, and the best way to do this is to visualize and quantify defect sizes by X-ray microCT. It is also possible to routinely check castings to ensure nothing changes in your process, eg. you can select every 100th part and subject it to scanning. Of course we could also scan all your parts, the method is entirely non-destructive and therefore valuable for high-performance applications to make 100% sure there are no porosities present. Below are a series of images and videos demonstrating casting porosity analysis in two parts, both light metal alloys of 50 and 150 mm diameter.

This presentation in PDF has embedded videos, please view in Adobe and not in internet browser to see the videos (save to disk and open):
SG le Roux – Casting Presentation shorter3

In case the PDF file with embedded videos does not work, see below selected images and videos from these two casting examples:

Casting microCT scan – x-rays

casting slice video

Rotation 1

Rotation 2

Rotation 3

Rotation 4