Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Analysis and Monitoring of Laser Welding and Surface Texturing
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Lasernova AB.ORCID iD: 0000-0002-7706-6994
2019 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Analys och övervakning av lasersvetsning samt ytstrukturering (Swedish)
Abstract [en]

This thesis can be conveniently divided into three sections as follows;

Part I. Monitoring of laser welding 

In laser materials processing there has always been a need for suitable methods to supervise and monitor the processes on-line, to ensure correct production quality or to trigger alarms when failures are detected. Numerous investigations have been made in this field, including experimental and theoretical work. It is common practice in this field to monitor surface temperature, plasma radiation and back-reflected laser light, coaxially with the laser beam.  Traditionally, the monitoring systems involved carry out no statistical analysis of the signals received – they merely involve thresholds.

The first two papers in this thesis look at the feedback collected during laser welding using a co-axial setup from a Digital Signal Processing point of view and also uses high speed video photography to correlate signal perturbations with process anomalies. Digital signal processing techniques such as Kalman filtering, Principal Component Analysis and Cluster Analysis have been applied to on-line measurement data and have generated new ways to describe laser welding behaviour using parameters such as reflected pulse shape. The limitations of commercially available welding supervision systems have been studied and design suggestions for the next generation of on-line weld monitoring equipment have been formulated.

Having progressed from thin section welding with continuous wave lasers to pulsed laser welding, the thesis then moves on to pulsed laser surface melting.

Part II Analysis of surface texturing of titanium.

The second part of the thesis concentrates on laser structuring of titanium surfaces for medical implants. The two papers in this section present an analysis of the laser-material interactions which create surfaces suitable for osseointegration (bone attachment). The work concentrates on a commercially available surface used for screw implants in dentistry; BioHelix™. This surface is generated by an intense bombardment of laser pulses and the surface is thus disrupted during solidification. The formation of various levels and types of roughness are analysed and it is noted that laser generated rough surfaces are fundamentally different from those with a mechanically produced roughness. One key point is that laser generated rough surfaces can include overhanging features. This finding lead to the research carried out in part III of the thesis.

Part III. Analysis and classification of laser generated surfaces.

The final section of the thesis presents research which uses statistical techniques to identify whether or not a roughened surface includes overhanging features. The presence or otherwise of such features is important because they can affect the wettability of surfaces and thus their suitability for implant surfaces, adhesive bonding and lubrication etc. Micro Computer Tomography was used to generate a typical cross section of the surface under investigation. At equally spaced positions the profile of this cross section is then allocated vectors which are normal to the profile at each point. The angles of the vectors can then be analyzed to reveal the presence or otherwise of overhanging features. The presence of overhangs on the material surface is indicated by the existence of normal vectors with angles that exceed 180°. The papers in this section also investigate possibilities and limitations of using statistical methods in conjunction with Micro Computer Tomography.

The papers have in common processing of data for laser materials processing, by advanced methods to identify and extract essential information from the processes and the resulting material properties.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2019.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords [en]
Laser welding, monitoring, Signal processing, laser texturing, texture analysis
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-74145ISBN: 978-91-7790-404-5 (print)ISBN: 978-91-7790-405-2 (electronic)OAI: oai:DiVA.org:ltu-74145DiVA, id: diva2:1319744
Public defence
2019-10-15, E632 - Studion, Luleå tekniska universitet, Luleå, 09:00 (English)
Opponent
Supervisors
Available from: 2019-06-04 Created: 2019-06-03 Last updated: 2019-09-18Bibliographically approved
List of papers
1. Advances in pulsed laser weld monitoring by the statistical analysis of reflected light
Open this publication in new window or tab >>Advances in pulsed laser weld monitoring by the statistical analysis of reflected light
2011 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 49, no 11, p. 1352-1359Article in journal (Refereed) Published
Abstract [en]

This paper describes two new techniques for monitoring the quality of laser welds by statistical analysis of the reflected light signal from the weld surface. The first technique involves an algorithm that analyses the variance of the peak values of the reflected signal as a measure of the stability of the surface during pulsed Nd:YAG laser welding in the heat conduction mode. Kalman filtering is used to separate a useful signal from the background noise. A good correlation between weld disruption and signal fluctuation has been identified. This technique could be used in tandem with the present practice of simply using the peak values of reflected (or emitted) light as an indicator of weld quality. The second technique investigated involves an assessment of the temporal shape of the power distribution of individual reflected pulses in comparison with an average of the results from a high quality weld. Once again a high correlation between a poor signal match and inferior quality welding was discovered, which may pave the way towards a new generation of optical weld monitoring devices.

National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-7442 (URN)10.1016/j.optlaseng.2011.05.010 (DOI)000294578800017 ()2-s2.0-79961171486 (Scopus ID)5d1fec5f-4840-4050-87d9-dd39a9c841f1 (Local ID)5d1fec5f-4840-4050-87d9-dd39a9c841f1 (Archive number)5d1fec5f-4840-4050-87d9-dd39a9c841f1 (OAI)
Note
Validerad; 2011; 20110703 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-06-03Bibliographically approved
2. Challenges to the interpretation of the electromagnetic feedback from laser welding
Open this publication in new window or tab >>Challenges to the interpretation of the electromagnetic feedback from laser welding
Show others...
2011 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 49, no 2, p. 188-194Article in journal (Refereed) Published
Abstract [en]

This paper considers the point that it is not possible to interpret individual weld perturbations from the raw electromagnetic feedback collected from laser weld zones. The presentation of electromagnetic data as a 3D cloud is presented as a new, useful tool in the analysis of this feedback. It is shown that there is a very low correlation between the plasma or thermal signals and the reflected light signal from the weld zone, and that a strong correlation exists between the plasma and thermal signals. It is also demonstrated that data points from a weld perturbation form a different 3D cluster to those from the stable welding process. A strategy for future real time data analysis is presented utilising a suitably shaped data cloud envelope. The rates of data fit to the various segments of such an envelope could be correlated with specific weld anomalies.

Keywords
Materials science - Other material science, Teknisk materialvetenskap - Övrig teknisk materialvetenskap
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-8299 (URN)10.1016/j.optlaseng.2010.08.018 (DOI)000285169500002 ()2-s2.0-78449248930 (Scopus ID)6cb4a7c0-d60a-11df-8b36-000ea68e967b (Local ID)6cb4a7c0-d60a-11df-8b36-000ea68e967b (Archive number)6cb4a7c0-d60a-11df-8b36-000ea68e967b (OAI)
Note

Validerad; 2011; 20101012 (ricols)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-06-03Bibliographically approved
3. The production of osseointegrating (bone bonding) surfaces on titanium screws by laser melt disruption.
Open this publication in new window or tab >>The production of osseointegrating (bone bonding) surfaces on titanium screws by laser melt disruption.
Show others...
2018 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 30, no 4, article id 042009Article in journal (Refereed) Published
Abstract [en]

Several techniques can be used to modify implant surfaces in order to accelerate bone growth around titanium implants. One method is to generate a surface structure which stimulates bone growth and remodelling. This paper describes and explains a non-ablative method for producing osseointegrating (structural and functional bone bonding) surfaces on titanium implants using laser processing. The focus is especially on surface texturing of dental implant screws, where the ability of a Nd:YAG laser to generate ‘splashy’ surfaces covered in resolidified micro scale droplets coated with nano-scale surface oxides is assessed. The surfaces produced were analysed by scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS). It is concluded that laser processing using Q-pulsed Nd:YAG lasers can generate surfaces which match the demands set by clinical experience. One important characteristic of the surfaces discussed here is that they involve overhanging features which are suitable for trapping red blood cells and which cannot be created by mechanical or chemical roughening techniques.

Place, publisher, year, edition, pages
Melville, NY: American Institute of Physics (AIP), 2018
Keywords
Medical implants, dental implants, osseointegration, titanium, laser surface structuring, high speed imaging.
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-71704 (URN)10.2351/1.5078502 (DOI)000451729800010 ()2-s2.0-85056997363 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-03 (inah)

Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2019-06-03Bibliographically approved
4. Formation of osseointegrating (bone integrating) surfaces on titanium by laser irradiation
Open this publication in new window or tab >>Formation of osseointegrating (bone integrating) surfaces on titanium by laser irradiation
Show others...
2019 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, no 2, article id 022508Article in journal (Refereed) Published
Abstract [en]

Pulsed lasers can be used to modify the surface of medical implants in order to accelerate bone growth (osseointegration). A surface covered in attached droplets with diameters between 1 and 20 μm is a beneficial surface for rapid osseointegration. This paper presents the results of an experimental program in which a broad range of laser parameters and different atmospheres were used to create different surface textures on titanium substrates, including the desired "attached droplet" topology. The resulting surfaces were analyzed by scanning electron microscopy and micro-computer tomography. The paper explains how different types of surfaces are created by the laser-material interaction under different conditions and focus characteristics. It is shown that optimization of the laser parameters results in a robust process, which produces a surface that is fundamentally different from those created by nonlaser methods.

Place, publisher, year, edition, pages
Laser Institute of America, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73825 (URN)10.2351/1.5096075 (DOI)000484435200078 ()2-s2.0-85064218607 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-05-03 (johcin)

Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-10-01Bibliographically approved
5. Normal vector distribution as a new classification tool for rough surfaces
Open this publication in new window or tab >>Normal vector distribution as a new classification tool for rough surfaces
(English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387Article in journal (Refereed) Submitted
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:ltu:diva-74143 (URN)
Conference
ICALEO
Available from: 2019-06-03 Created: 2019-06-03 Last updated: 2019-06-03
6. Formation mechanisms of surfaces for osseointegration on titanium using pulsed laser spattering
Open this publication in new window or tab >>Formation mechanisms of surfaces for osseointegration on titanium using pulsed laser spattering
Show others...
2019 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 458, p. 158-169Article in journal (Refereed) Published
Abstract [en]

Accelerated bone grow (osseointegration) can be achieved by modifying the surface of medical implants. For this purpose, pulsed lasers can be used to successfully texture such beneficial surfaces on titanium, e.g. a BioHelix™ structure. This surface typically includes ridges and droplets with a size range between 1 and 20 μm. This paper presents the results of an experimental program where a range of laser parameters was used to create different surface textures on titanium substrates, using pulsed laser spattering. The resultant surfaces are analysed by scanning electron microscope and X-ray Micro Computer Tomography. It is shown that optimisation of the laser parameters results in a robust process which produces a surface that has proven to be beneficial for osseointegration. The results are also deeper analysed, explaining how different types of surface are created by the laser-material interaction under different conditions. Further, droplet flight distances and the formation of the spongeous nano-scale surface that characterizes the surface structure depends on very fast cooling and is also evaluated.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Osseointegration, Titanium, Laser, Surface, Spatter, BioHelix
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73791 (URN)10.1016/j.apsusc.2019.04.187 (DOI)000472183900020 ()2-s2.0-85067607616 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-09 (johcin)

Available from: 2019-04-30 Created: 2019-04-30 Last updated: 2019-07-09Bibliographically approved
7. Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions
Open this publication in new window or tab >>Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions
(English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545Article in journal (Refereed) Submitted
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:ltu:diva-74144 (URN)
Available from: 2019-06-03 Created: 2019-06-03 Last updated: 2019-06-03

Open Access in DiVA

fulltext(29641 kB)34 downloads
File information
File name FULLTEXT01.pdfFile size 29641 kBChecksum SHA-512
6b905df87d5d7a171efb82e57adcd63a53cc55355a572abd4db186df2c589e9197d58fa8cb224832d392382aebed172cf4d30c8759628a1b1d5b7f18e5d38792
Type fulltextMimetype application/pdf

Authority records BETA

Olsson, Rickard

Search in DiVA

By author/editor
Olsson, Rickard
By organisation
Product and Production Development
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 34 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 275 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf