AM Part Verification ToolKit
Posted on April 21st, 2022
“So that’s right. And those constraints created the opportunity for additive. They’re now working out the process. And part of that process involves developing a new mode of certifying a component…. And if we can certify qualified parts to go inside of a nuclear reactor, I think that we can certify and qualify parts to do nearly anything…. So this component offered the chance not just to prove out 3D printing in a part that goes into a reactor, but also to pioneer the process for how you certify an additively manufactured part. And it turns out additive manufacturing not only brings the promise of a lot of new design freedoms for nuclear power components, but also potentially a new level of capability when it comes to certifying parts.”
Peter Zelinski, Editor-in-Chief, The Cool Parts Show
We have been hard at work developing a software product to bring a new “Digital Inspection” capability to additive manufacturing. Initial roll-out will be for Marlin based Material Extrusion systems with follow-on efforts to cover the full range of ASTM defined AM categories.
Why Material Extrusion as a starting point? Great question. The goal of this research is to bring a level of protection to American Small Medium Manufacturers (SMM’s) who desperately need an advantage. This category of company lacks cybersecurity resources and are huge targets for disruptive cyber threats.
Traditional inspection fails to account for AM specific process settings that are not traditionally “measure-able.” Structured light scanning can tell you, down to the micron, how accurately a part was produced to the native CAD. The issue is 3D printers do not always print “true to CAD ” and instead optimize a component with infill and shells etc. Physical inspection will not tell you the whole picture when it comes to qualifying AM components. A part might be well within tolerance as far as dimensional accuracy is concerned but still fail in a catastrophic manner if the AM technician oriented the component on its side instead of the intended print orientation. (ASTM DogBone image example below)
BISON adds a layer to the verification process of additively manufactured components by providing a GCODE trace of the exact instructions sent to a printer. This has a much wider “real-world” application than simply saving the “as-prepared”, or source, GCODE file. There are many alterations that can happen mid print that make a GCODE trace have greater insights into a parts quality. These alterations can be as simple as an operator changing material mid-print to a hacker inserting malicious commands to disrupt the process with intent of causing component failure post print or machine damage mid print.
This digital verification layer will be complementary to typical quality assurance (QA) processes and integrate seamlessly into the background with little to no additional labor as the collection and retention is automated. Having this data stream preserved will be crucial for performing root cause analysis on failed components. If an AM component fails it is normal to review the inspection report generated from physical inspection procedures. If there are no obvious causes for the failure a deeper dive would be to inspect the GCODE trace provided by BISON.
A bracket printed on a MarkForged composite (continuous carbon fiber reinforced) machine might fail but have no evidence of what precipitated the failure when solely viewed from physical inspection and ignoring the digital manufacturing dataset that was used for fabrication. This is not a good situation as then the component might be subjected to a redesign. If BISON managed to capture the GCODE trace for that particular serial number, it would be obvious that the fiber deposition path had been subverted from a compromised slice engine. With this knowledge a team can begin a cyber incident plan instead of an engineering redesign of a component that does not need rework.
Digital AM Verification
BISON GCODE trace rendering will be a complimentary tool in the AM verification process to existing physical inspection. Parameters that are “invisible” to physical inspection become obvious when complimented with this new “cyber-inspection” capability.
BISON GCODE trace rendering will not reveal physical process defects (partially clogged toolhead, warping off print bed). As far as BISON GCODE trace rendering is concerned the left and the right images (below) are identical. This is an exaggerated example of where physical AM verification tools are appropriate.
Physical AM Verification
Physical non destructive inspection methods (can be done in-situ and or post production) include;
An example of this physical inspection software toolkit would be Geomagic ControlX. It does not reveal digital inputs that impact the mechanical properties of the manufactured component. As far as physical inspection goes the image on the left and right are the same but this is detectable with BISON GCODE trace rendering.
Real World Scenarios
An operator accidentally turns the encoder wheel on the Human-Machine Interface (HMI) while on the home screen and not the menu. This is incredibly common and non malicious. The proper procedure to access the menu is to press the encoder wheel prior to turning. When turned mid-print from the home screen the feed rate parameter is increased or decreased. What started as a simple task to pause and change the filament ends up changing a parameter that could later induce a failure – in dramatic cases if the speed is ramped up too much layers will not adhere correctly as the extruder does not have the thermal capacity to melt and push feedstock at the accidental speed override.
Here is an image from Simplify3D showing a prepared (non trace) GCODE where speed changes have been inserted. BISON can detect changes like this that originate during a print job bringing real world utility and new capability for QA insights that have previously not been possible.
We are rapidly refining this product and have been making huge performance refinements, operations taking 5 minutes are now completing in 2 seconds. Training materials will be available soon.
If you are interested in learning more about securing AM or a demonstration of the BISON capability, please contact us at firstname.lastname@example.org