Measurement and characterisation of additively manufactured surface texture
Lead Research Organisation:
University of Huddersfield
Department Name: Sch of Computing and Engineering
Abstract
Having a number of advantages over conventional (subtractive) manufacturing techniques, AM technologies possess the potential to change the paradigm for manufacturing. To facilitate the successful uptake of AM technologies into a wider range of applications, AM needs metrological methods to measure, evaluate and validate both AM processes and AM parts, in order to improve the accuracy and reliability of AM products.
The compound complexities of surface geometry and surface topography of AM parts have caused many problems for existing surface measurement techniques, including tactile, optical and XCT methods. Furthermore, due to the nature of AM processes, the AM-produced surface topography differs from conventionally machined surfaces. Following conventional surface characterisation methods, without considering the unique characteristics of AM surface topography, cannot lead to reliable and meaningful results. This dilemma is further aggravated by the complex surface geometry of the functional AM components, which result in serious distortions to surface characterisation techniques.
Facing these challenges, this research programme will investigate the applicability of various methods for the measurement of AM surface texture, including tactile, optical and XCT techniques. It will also develop bespoke surface characterisation methods for AM layer surfaces, aiming to reflect the characteristics of AM processes, and advanced surface characterisation methods needed for complex AM surfaces, with the aim of predicting the functionality of AM products.
The project aligns with the EPSRC's 'Manufacturing Technologies' topic within 'Manufacturing the Future' theme, and meets the UK's national strategy on AM technology. The outcome of this project will contribute to the control of AM process, and verification of AM product quality. It has great potential to positively impact on the UK's economy through the exploitation of AM technology in the key sectors concerned with high value manufacturing, including the aerospace, healthcare, high-end automotive and creative industries.
The compound complexities of surface geometry and surface topography of AM parts have caused many problems for existing surface measurement techniques, including tactile, optical and XCT methods. Furthermore, due to the nature of AM processes, the AM-produced surface topography differs from conventionally machined surfaces. Following conventional surface characterisation methods, without considering the unique characteristics of AM surface topography, cannot lead to reliable and meaningful results. This dilemma is further aggravated by the complex surface geometry of the functional AM components, which result in serious distortions to surface characterisation techniques.
Facing these challenges, this research programme will investigate the applicability of various methods for the measurement of AM surface texture, including tactile, optical and XCT techniques. It will also develop bespoke surface characterisation methods for AM layer surfaces, aiming to reflect the characteristics of AM processes, and advanced surface characterisation methods needed for complex AM surfaces, with the aim of predicting the functionality of AM products.
The project aligns with the EPSRC's 'Manufacturing Technologies' topic within 'Manufacturing the Future' theme, and meets the UK's national strategy on AM technology. The outcome of this project will contribute to the control of AM process, and verification of AM product quality. It has great potential to positively impact on the UK's economy through the exploitation of AM technology in the key sectors concerned with high value manufacturing, including the aerospace, healthcare, high-end automotive and creative industries.
Planned Impact
The proposed research programme, along with its outputs, will produce impacts across a range of groups.
1) Impact on the metrology industry
The metrology industry will be a direct beneficiary of a new generation of surface characterisation methods. It will open the door for XCT to become a valid tool for surface texture measurement, and thereby promote the adoption of XCT into surface metrology. It will also provide the metrology industry with a feasible solution for the inspection of complex AM products, which can be very difficult if using traditional measurement techniques.
2) Impact on AM stakeholders in key industrial sectors
The proposed project will benefit three key industrial sectors that extensively exploit AM technologies, i.e., aerospace, automotive and healthcare. In the aerospace sector, it will provide a metrological solution to verify that the surface quality of complex functional AM components lives up to the necessary stringent requirements; in the automotive industry, it will facilitate the quality control of AM parts, the geometrical non-conformance and manufacturing defects of which are of significant concern; in healthcare, it will help in the investigation of the bio-compatibility of surface texture in medical AM components, in terms of cell attachment and tissue growth.
3) Impact on wider industrial beneficiaries through the project partners
The proposed project, in collaboration with the National Physical Laboratory (NPL), will have an impact on NPL's relevant Good Practice Guides, and thus will inform the wide scope of industrial metrologists on how to effectively measure and characterise AM surface texture. Cooperation with the Manufacturing Technology Centre (MTC) will enable broadcasting the research outputs to a wider range of end-users in the high value manufacturing sector, helping them with AM product quality control. The impact on further AM exploiters, which require their AM components to have greater accuracy, surface finish or mechanical performance will, be through the MAPP EPSRC Future Manufacturing Hub of the University of Sheffield (MAPP: Manufacture using Advanced Powder Process).
4) Impact on the host institute
The proposed research programme aligns with the 'Metrology for Additive Manufacturing' platform topic of the recently-launched Future Advanced Metrology Hub (an EPSRC Future Manufacturing Hub), based at the Centre for Precision Technology (CPT) of the University of Huddersfield (UoH). It will strengthen CPT's research capability concerning surface metrology, and promote its participation in the development and enhancement of the relevant metrology standards.
5) Impact on staff development
Two PGR students and a PDRA involved in this project will be trained in a multi-disciplinary skill set, covering precision metrology, AM, applied mathematics and computer programming. Moreover, the research will enhance the learning experience of postgraduate students through the Advanced Metrology MSc course and other training activities delivered by the CPT.
6) Impact on society and economics
The proposed research programme will impact the UK's economy through the exploitation of AM technology in key sectors, concerned with high value manufacturing. It will also contribute to environmental and social sustainability through reducing scrap, saving raw materials, lowering CO2 emissions and being better personalised to suit consumers.
1) Impact on the metrology industry
The metrology industry will be a direct beneficiary of a new generation of surface characterisation methods. It will open the door for XCT to become a valid tool for surface texture measurement, and thereby promote the adoption of XCT into surface metrology. It will also provide the metrology industry with a feasible solution for the inspection of complex AM products, which can be very difficult if using traditional measurement techniques.
2) Impact on AM stakeholders in key industrial sectors
The proposed project will benefit three key industrial sectors that extensively exploit AM technologies, i.e., aerospace, automotive and healthcare. In the aerospace sector, it will provide a metrological solution to verify that the surface quality of complex functional AM components lives up to the necessary stringent requirements; in the automotive industry, it will facilitate the quality control of AM parts, the geometrical non-conformance and manufacturing defects of which are of significant concern; in healthcare, it will help in the investigation of the bio-compatibility of surface texture in medical AM components, in terms of cell attachment and tissue growth.
3) Impact on wider industrial beneficiaries through the project partners
The proposed project, in collaboration with the National Physical Laboratory (NPL), will have an impact on NPL's relevant Good Practice Guides, and thus will inform the wide scope of industrial metrologists on how to effectively measure and characterise AM surface texture. Cooperation with the Manufacturing Technology Centre (MTC) will enable broadcasting the research outputs to a wider range of end-users in the high value manufacturing sector, helping them with AM product quality control. The impact on further AM exploiters, which require their AM components to have greater accuracy, surface finish or mechanical performance will, be through the MAPP EPSRC Future Manufacturing Hub of the University of Sheffield (MAPP: Manufacture using Advanced Powder Process).
4) Impact on the host institute
The proposed research programme aligns with the 'Metrology for Additive Manufacturing' platform topic of the recently-launched Future Advanced Metrology Hub (an EPSRC Future Manufacturing Hub), based at the Centre for Precision Technology (CPT) of the University of Huddersfield (UoH). It will strengthen CPT's research capability concerning surface metrology, and promote its participation in the development and enhancement of the relevant metrology standards.
5) Impact on staff development
Two PGR students and a PDRA involved in this project will be trained in a multi-disciplinary skill set, covering precision metrology, AM, applied mathematics and computer programming. Moreover, the research will enhance the learning experience of postgraduate students through the Advanced Metrology MSc course and other training activities delivered by the CPT.
6) Impact on society and economics
The proposed research programme will impact the UK's economy through the exploitation of AM technology in key sectors, concerned with high value manufacturing. It will also contribute to environmental and social sustainability through reducing scrap, saving raw materials, lowering CO2 emissions and being better personalised to suit consumers.
Publications
Liu W.
(2022)
INVESTIGATE GEOMETRY AND SURFACE TEXTURE OF SELECTIVE LASER MELTING BUILT INTERNAL CHANNELS WITH VARYING INCLINATION ANGLES USING XCT
in 2022 ASPE and euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing
Lou S
(2020)
Watershed segmentation of topographical features on freeform surfaces and its application to additively manufactured surfaces
in Precision Engineering
Lou S
(2019)
Characterisation methods for powder bed fusion processed surface topography
in Precision Engineering
Lou S
(2020)
Application of Clustering Filter for Noise and Outlier Suppression in Optical Measurement of Structured Surfaces
in IEEE Transactions on Instrumentation and Measurement
Lou S
(2019)
Surface texture evaluation of additively manufactured metallic cellular scaffolds for acetabular implants using X-ray computed tomography
in Bio-Design and Manufacturing
Lou S
(2021)
Material ratio curve of 3D surface topography of additively manufactured parts: an attempt to characterise open surface pores
in Surface Topography: Metrology and Properties
Lou S.
(2022)
3D SURFACE TEXTURE CHARACTERISATION TECHNIQUES FOR ADDITIVE MANUFACTURING COMPONENTS
in 2022 ASPE and euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing
| Description | 1. The research has identified and comprehensively investigated the key factors influencing surface quality, such as surface inclination and critical process parameters. Bespoke surface characterisation techniques have been developed to accurately reflect their impacts. 2. It has been discovered that the surface quality of additive manufacturing (AM) components significantly affects their mechanical performance (e.g. tensile strength) and bioengineering properties (e.g. osseointegration). The newly developed 3D surface characterisation methods enable a more robust and reliable assessment of these effects. 3. The capability of X-ray computed tomography (XCT) to measure AM surface texture has been evaluated by comparing it to an optical focus variation microscope. This evaluation, conducted using the modulation transfer function, has led to further improvements in XCT's performance via reconstructing the focus spot and applying deconvolution methods. 4. The research has investigated the impact of rough surface texture resulting from AM processes on dimensional measurements of AM components. This investigation has employed both physical experiments and simulation techniques. The simulation approach, in particular, has contributed to the development of digital twins for the metrology of AM production, enhancing accuracy and efficiency in quality control processes. |
| Exploitation Route | 1. Designers and end-users of Additive Manufacturing (AM) products will gain a comprehensive understanding of AM surface characteristics and their impact on product performance. Process engineers involved in AM will benefit from the ability to control process parameters to achieve desired surface quality. The developed metrology technology serves to bridge the gap between AM processes and product functionality, advancing additive manufacturing towards more facilitating manufacturing technologies. 2. The knowledge generated will also be integrated into the development of relevant AM standards through the British Standards Institution and ISO. 3. The enhancement of resolution in XCT will be disseminated to XCT OEMs through subsequent funding leverage. The improved capability of XCT will transform it into a more effective non-destructive inspection tool for verifying the quality of AM products, thereby promoting the adoption of AM technologies in more critical applications. 4. The developed 3D surface characterisation will be transferred to metrology software partners and distributed to a wide range of end-users across various research communities and industrial sectors, such as aerospace, automotive, healthcare, and energy. |
| Sectors | Aerospace Defence and Marine Environment Healthcare Manufacturing including Industrial Biotechology |
| Description | The grant-funded research has significant economic and societal impacts, particularly in industries reliant on additive manufacturing (AM) technology. 1. The developed methods for surface measurement and characterisation contribute substantially to quality assurance in AM. This is crucial for safety-critical industrial sectors like aerospace and healthcare, as it ensures the reliability and integrity of AM components. By enhancing quality assurance, these methods facilitate the broader adoption of AM technology for commercial applications, thus stimulating economic growth within these sectors. 2. The innovative 3D surface characterisation techniques enable the manipulation of XCT scan point cloud and triangular mesh data. This capability allows for comprehensive analysis of freeform shapes and local re-entrant features in the surface topography of AM components. By enhancing the understanding of surface characteristics, these techniques aid in the optimisation of the AM process and improve the functionality of AM products. This, in turn, leads to more efficient production processes and higher quality end-products, benefiting both economic performance and consumer satisfaction. 3. The research significantly enhances the capability of XCT to measure small-scale AM surface textures. By comprehensively investigating and improving this capability, XCT becomes more effective for non-destructive inspection of AM components. This advancement is crucial for ensuring the reliability and safety of AM products in various applications. It reduces the risk of defects and failures, ultimately contributing to cost savings and enhancing confidence in the technology's reliability, thereby encouraging further adoption in both industrial and societal contexts. |
| First Year Of Impact | 2022 |
| Sector | Aerospace, Defence and Marine,Education,Environment,Healthcare,Manufacturing, including Industrial Biotechology |
| Impact Types | Economic |
| Description | Comments to the draft ISO 52902 (AM-Test Artefacts-Geometric Capability) |
| Geographic Reach | Multiple continents/international |
| Policy Influence Type | Contribution to new or Improved professional practice |
| Impact | This ISO standard affects the measurement practice for the additive manufacturing industry. |
| Description | 3M Buckley Innovation Centre Fellowship - Working towards holistic geometrical verification of additive manufacturing components |
| Amount | £9,000 (GBP) |
| Organisation | 3M Buckley Innovation Centre |
| Sector | Private |
| Country | United Kingdom |
| Start | 03/2021 |
| End | 03/2023 |
| Description | Future Metrology Hub Innovation Project - A toolbox for freeform triangle mesh surface characterisation and its verification method |
| Amount | £80,000 (GBP) |
| Organisation | University of Huddersfield |
| Department | Future Metrology Hub |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 03/2023 |
| End | 04/2024 |
| Description | Future Metrology Hub Innovation Project - Investigation of Dimensional Accuracy and Surface Roughness of Polymeric Parts Manufactured by Additive Manufacturing |
| Amount | £80,000 (GBP) |
| Organisation | University of Huddersfield |
| Department | Future Metrology Hub |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 03/2023 |
| End | 04/2024 |
| Description | PhD studentship sponsored by National Physics Laboratory (Miss Xiao Chen, Measurement of 3D additively measured surface texture) |
| Amount | £27,000 (GBP) |
| Organisation | National Physical Laboratory |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 03/2019 |
| End | 04/2023 |
| Title | Measurement database for selective laser melting artefact with various surface orientation |
| Description | A bespoke artefact named 'truncheon' was fabricated by selective laser melting. The truncheon has various surface orientation ranging from 0-180 degree with 3 degree increment. Each inclined surface was measured by focus variation microscope in three different locations, leading to the construction of a large database of measurement data. This database facilitated the investigation on how surface topography and associated surface texture parameters vary in respect to surface inclination. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2021 |
| Provided To Others? | Yes |
| Impact | The database led to the publication of the journal paper 'Surface Texture Characterization of Metal Selective Laser Melted Part with Varying Surface Inclinations'. It makes impact on the additive manufacturing community on targeting suitable surface texture parameters to link with process control and functional performance. The database is available per reasonable request. |
| Description | Collaboration of the MTC on investigating surface topography of selective laser melted part with varying surface inclination angles |
| Organisation | Manufacturing Technology Centre (MTC) |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Dr Shan Lou provided the initial idea of this research, the expertise of surface characterisation, and supervision of research students. Two PhD research students, Mr Shubhavardhan Narasimharaju and Mr Weidong Liu conducted the measurement and data analysis. |
| Collaborator Contribution | The MTC partner helped fabricate the bespoke artefact and provided the expertise of the SLM process. |
| Impact | This collaboration led to two joint publications: Narasimharaju, S.R., Liu, W., Zeng, W., See, T.L., Scott, P., Jiang, X. and Lou, S., 2021. Surface texture characterization of metal selective laser melted part with varying surface inclinations. Journal of Tribology, 143(5), p.051106. Liu, W., Chen, X., Zeng, W., Sun, W., Gorman, D., Wilson, A., Qi, Q., Scott, P., Jiang, X. and Lou, S., 2024. Comparison of X-ray computed tomography and coordinate-measuring system dimensional measurement for additive manufacturing parts using physical and simulation methods. Measurement, p.114414. |
| Start Year | 2020 |
| Description | Collaboration of the NPL on investigating measurement techniques for additively manufactured parts |
| Organisation | National Physical Laboratory |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Dr Shan Lou provided the expertise in surface texture measurement and simulation and supervision of research student. The PhD student, Miss Xiao Chen, is working on comparing XCT with tactile and optical techniques for AM surface texture measurement and improving XCT's metrological resolution via reconstructing X-ray focal spot and applying deconvolution for deburring. |
| Collaborator Contribution | The NPL partner provides the expertise of XCT, surface texture measurement, student joint-supervision, as well as financial support. |
| Impact | This collaboration led to four joint publications so far now: W. Sun, X. Chen, C. Guisca, S. Lou, C. Jones, H Boulter, S. Brown, Evaluation of X-ray computed tomography for surface texture measurements using a prototype additively manufactured reference standard, 11th Conference on Industrial Computed Tomography, Wels, Austria W. Sun, C. Giusca, S. Lou, X. Yang, X. Chen, A. Wilson, H. Boulter, X. Jiang, S. Brown 2022 Establishment of X-ray computed tomography for surface texture evaluation using an additively manufactured reference standard, Additive Manufacturing 50: 102558 S. Lou, S. Brown, W. Sun, W. Zeng, X. Jiang, P. J. Scott 2019 An investigation of the mechanical filtering effect of tactile CMM in the measurement of additively manufactured parts, Measurement, 144: 173-182. X. Chen, Q. Zhang, W. Sun, W. Zeng, X. Jin, P. J. Scott, X. Jiang, S. Lou 2020 Development of virtual reference samples for XCT measurements of additively manufactured surface texture, 10th Conference on Industrial Computed Tomography, Wels, Austria. |
| Start Year | 2019 |
| Description | Collaboration with Digital Surf on 3D freeform surface characterisation |
| Organisation | Digital Surf |
| Country | France |
| Sector | Private |
| PI Contribution | (1) Develop a general framework for the triangle mesh-based complex freeform surface characterisation; (2) Develop a robust association method for the separation of nominal form and surface textures of surface with known nominal geometry; (3) Develop a reliable and distortion-free triangle mesh filtration method for the decomposition of different surface components; |
| Collaborator Contribution | Digital Surf provide the industrial guidance and assistant for the development |
| Impact | Future Metrology Hub - Innovation Project: A toolbox for freeform triangle mesh surface characterisation and its verification method |
| Start Year | 2021 |
| Description | Collaboration with Singapore A*STAR Advanced Remanufacturing and Technology Centre on AM XCT metrology |
| Organisation | Advanced Remanufacturing Technology Centre |
| Country | Singapore |
| Sector | Private |
| PI Contribution | (1) 3D surface texture characterisation techniques based on XCT-generated triangular mesh, useful for the analysis of additively manufactured lattice structures. (2) Correlate surface quality of lattice structures to the compression performance. |
| Collaborator Contribution | (1) Design and fabrication of metal additively manufactured lattices. X-ray CT scanning of the fabricated AM lattices. (2) Development of algorithms to characterize the dimensions and surface roughness of the fabricated lattices. (3) Functional mechanical testing of the fabricated AM lattices. |
| Impact | (1) 1 joint PhD studentship (Mr Ronnie Ssebaggala); A*Star sponsors the student via its A*Star research attachment programme, including two years bursary, one-time airfare grant, settling-in allowance, housing subsidy, medical insurance and conference & IT allowance; Project: Precision Metrology of Additively Manufactured Lattice Structures Using Industrial X-Ray Computed Tomography (2) 1 MSc by Research part-time student (Mr Bisma Mutiargo); A*Star sponsors Mr Mutiargo with a full-time salary while he is visiting in the UK; Project: Fast surface determination method based on XCT simulation and machine learning |
| Start Year | 2021 |
| Description | Collaborations with Sartorius Stedim Lab Ltd. on Metrology for Polymeric Parts Manufactured by Additive Manufacturing |
| Organisation | Sartorius |
| Department | Sartorius Stedim UK Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | (1) To target the capable measurement techniques and associated optimum measurement settings for Sartorius AM parts guided by the existing experimental and simulation research outcome; (2) To apply the developed advanced geometry characterisation techniques (fitting, filtration and segmentation) to verify the dimensional accuracy and surface roughness of Sartorius AM parts; (3) To optimise the established AM processes/post-processes at Sartorius and to correlate surface geometry of Sartorius AM parts to their functionality (assembly, sealing and biological properties) |
| Collaborator Contribution | Sartorius will design artefacts with various features, which will be produced by in-house state-of-the-art AM systems including selective laser sintering, vat photopolymerisation, digital light processing and material extrusion. Different printing parameters will also be used to manufacture the artefacts. The selected printed artefacts will be further subject to post-processing by the cutting-edge vapour smoothening machine. Based upon the measurement results obtained from Huddersfield, further testing within Sartorius will be performed, including mechanical properties, biocompatibility, E&L properties. |
| Impact | (1) UoH Colloborative Ventures Funding: Investigation of Surface Roughness and Form Tolerance of Polymeric Parts Manufactured by Additive Manufacturing (2) Future Metrology Hub - Innovation Project: Investigation of Dimensional Accuracy and Surface Roughness of Polymeric Parts Manufactured by Additive Manufacturing |
| Start Year | 2022 |
| Title | Morphological filter plugin for Digital Surf's surface analysis software MountainMap |
| Description | A plugin software which provides 3D morphological filters were developed. This plugin was provided to the industrial partner Digital Surf under the license between the University of Huddersfield and the company. |
| Type Of Technology | Software |
| Year Produced | 2020 |
| Impact | Digital Surf is in the process of commericalising the plugin software and aims to provide its customers with a capability to deal with 3D triangular mesh data, e.g. XCT data. This is a great enhancement to their current product, which can only manager regular sampled lattice data. |
| Description | A technical presentation deliver to A*Star Advanced Remanufacturing and Technology Centre |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | ARTC & the University of Huddersfield (UoH) are seeking to build a relationship in the advanced metrology for additive manufacturing domain. Initial contact was made by a member of ARTC engineering staff who will be undertaking their Master's degree with Dr Lou at UoH in 2022. The proposed ARAP funded PhD project will facilitate staff exchange and knowledge exchange between ARTC and UoH. |
| Year(s) Of Engagement Activity | 2021 |
| Description | Invited talk on a Manufacturers Metrology Network event on Hybrid & Additive Manufacturing (hosted by National Physical Laboratory) |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Research outcome exposed to the wide manufacturing industry, and build more connections |
| Year(s) Of Engagement Activity | 2023 |
| Description | Research presentation to HiETA Technologies |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Dr Shan Lou was invited by Mr Henry Greenhalgh and Mr Cameron Breheny of the HiETA Technologies to introduce the research work in surface metrology for additive manufacturing. This was followed by a discussion on the interest of HiETA on surface texture and future colloboration. |
| Year(s) Of Engagement Activity | 2020 |