internal feature metrology for am - university of nottingham · internal feature metrology for am...
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Internal feature metrology for AM
Adam Thompson PhD Student 3D Printing & Additive Manufacture Research Group, Manufacturing Metrology Team
AM product examples
• Conformal cooling
Leonardo De Chiffre et al. 2015
• How can we verify these products? – Can’t measure it = Can’t make it – Additive manufacture Complex internal geometries – Traditional metrology (CMM, surface texture etc.)
• Great for surfaces and accessible form • Can’t measure internal structures without destruction
– The answer Volumetric measurement XCT
Motivation
X-ray computed tomography
• Measures the absorption of x-rays through a part • Object is rotated over large number of
incremental rotations • A computer is used to re-construct the result
XCT in AM review
• Summary of XCT and AM technologies • Historical overview of usage in reverse engineering and
AM metrology to present day, documenting trend from RE towards metrological XCT
• Summary of the current state: – RE in medicine for modelling and implant production – Measurement of pores and small features – XCT in dimensional metrology for AM
• Future research
Leonardo De Chiffre et al. 2015
Reverse engineering to metrology
• Clear trend over time: – First use of XCT was in modelling of a patient’s
skull
– Throughout the 90’s and 00’s, lots of reverse engineering, very few uses to inspect parts made via AM, but more appearing over time
Nicholas J Mankovich et al. 1990
Reverse engineering to metrology
– Generally very low quality scans in the early days – far too poor to be used metrologically beyond very basic inspection
– Last ten years: more studies where XCT used for direct measurement of parts
Simon Van Bael et al. 2011
Current state: medicine
• AM well established in modelling • Metrology becoming more
prevalent in part verification • Requirement for human clinical
trials of customised, allowing widespread use of this technology as a new, higher standard for implants and prostheses
Tsuyoshi Igami et al. 2014 Kosuke Kondo et al. 2015
Shuji Isotani 2015 H Kenngott et al. 2015
Hudák Radovan et al. 2014
Current state: pore measurements
• Well established as a measurement of porosity and pore morphology
• Increasingly correlating measurements with other data taken on other instruments
Holly D Carlton et al. 2015
Current state: pore measurements
• Measurement of designed & non-designed porosity now common using XCT – less accurate than measurements by other measurements but can examine pore distribution
A B Spierings A et al. 2011
Current state: pore measurements
• Two primary requirements:
– reducing of the limitation of resolution for the detection of small pores
– correlating porosity and pore distribution measurements to other cheaper measurement techniques
Current state: dimensional metrology
• Validation against CAD models
– Deviation maps
– XCT to FEA for reverse engineering
ChaBum Lee and Joshua A Tarbutton 2015 D Cooper D et al. 2015
Current state: dimensional metrology
• Medical component measurements
– Osseointegration
– Bioprinting
– Positional accuracy of implants
Silke Wüst et al. 2014 Huajun Huang et al. 2015 Jessica M Williams et al. 2005
Current state: dimensional metrology
• Measurements of lattice structures
– Strut dimensions
– Surface texture measurements
Eberhard Abele E et al. 2015 Seung K Seol et al. 2015
Current state: dimensional metrology
• AM and XCT artefact development
– XCT an AM collaboration now well established
– Artefact development in XCT and AM approaching standardisation
H-C Möhring et al. 2015 Matthew G et al. 2015 Shawn Moylan S et al. 2012
Current state: dimensional metrology
• Requirements:
– Continued XCT system calibration and verification
– New research regarding XCT measurement of surface texture
? ✓
Greet Kerckhofs et al. 2013
Future group research
• Develop validation techniques for XCT and AM
• XCT measurement of internal features and defects
• Develop IRM techniques to allow: – Reduce systematic errors
– Surface determination
– Speed up measurement process
– Enhance metrological characteristics (accuracy, dynamic range)