<?xml version="1.0" encoding="utf-8"?>
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  <doc>
    <id>6279</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber>10</pageNumber>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName>Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V. (WLT)</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Automated weld seam evaluation and 2D simulation parameter calibration for absorber-free laser transmission welding</title>
    <abstract language="eng">Absorber-free laser transmission welding enables clean and precise joining of plastics without additives or adhesives. It is therefore well suited to produce optical and medical devices, which place high demands on cleanliness and accuracy.&#13;
However, the weld usually has an undesirably large vertical expansion, causing bulges and distortion. To improve this, the intensity distribution of the laser beam as well as the processing strategy must be adapted. Due to the complexity, this is aided by process simulation. However, simulation parameter calibration and verification are usually done considering the seam width and height, which is of limited significance. To overcome this, we propose a new method for image processing of microtome sections, determining the spatially resolved geometry of the weld. Thus, the deviation between experiment and simulation can be calculated pixel by pixel. This spatially resolved value is predestined for the calibration of the simulation parameters: For a parameter field with 18 different settings, the total deviation between experiment and simulation is less than 11 % after calibration.</abstract>
    <parentTitle language="eng">Lasers in Manufacturing Conference (LIM 2023), 26. Juni bis 29. Juni 2023, München</parentTitle>
    <identifier type="url">https://www.wlt.de/sites/default/files/2023-09/Contribution_122.pdf</identifier>
    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Frederik Maiwald</author>
    <author>Johannes Tröger</author>
    <author>Stefan Hierl</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>plastics welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>image processing</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>simulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>optimization</value>
    </subject>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>928</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferencepresentation</type>
    <publisherName>pro Business GmbH</publisherName>
    <publisherPlace>Berlin</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Thermo-mechanical computation of weld seam geometry in laser transmission welding</title>
    <parentTitle language="eng">Applied Research Conference - ARC 2017, 7 July 2017, München</parentTitle>
    <subTitle language="eng">Poster Session</subTitle>
    <enrichment key="opus.source">publish</enrichment>
    <author>Frederik Maiwald</author>
    <author>Anton Schmailzl</author>
    <author>Stefan Hierl</author>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>8308</id>
    <completedYear/>
    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferencepresentation</type>
    <publisherName>Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V.</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Enhancing Layer Adhesion in Material Extrusion AM with Adaptive Laser Preheating Integrated in Printhead</title>
    <abstract language="eng">Material extrusion is a widely used AM process and is gaining more acceptance in industry applications due to its material variety, flexibility, and low cost. However, its usage is limited by a process-related anisotropy caused by insufficient interlayer bonding due to reduced temperature in the process zone. To enhance layer adhesion, an adaptive laser preheating system is integrated in a conventional printhead around the extrusion nozzle. The setup with eight fiber coupled diode laser allows preheating in feed direction and investigation of various intensity profiles. The article describes the experimental setup and significant improvements achieved. Laser preheating with different intensity distributions (spot, sickle or ring shaped) show an incasement of up to 85 % of the mechanical properties in the build-up direction. However, due to the additional energy input by the laser, controlled cooling of the workpiece becomes a crucial factor and is investigated as well.</abstract>
    <parentTitle language="deu">LiM Conference 2025, Lasers in Manufacturing, June 23 - 26, 2025, Munich, Germany</parentTitle>
    <identifier type="url">https://www.wlt.de/lim-conference</identifier>
    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Dennis Meisner</author>
    <author>Nikitas Kaftiranis</author>
    <author>Frederik Maiwald</author>
    <author>Petra Rapp</author>
    <author>Stefan Hierl</author>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>931</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>10</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName/>
    <publisherPlace>München</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Transformation of Weld Seam Geometry in Laser Transmission Welding by Using an Additional Integrated Thulium Fiber Laser</title>
    <parentTitle language="eng">Lasers in Manufacturing - LIM 2017, Conference Proceedings</parentTitle>
    <note>CD-ROM</note>
    <enrichment key="opus.source">publish</enrichment>
    <author>Anton Schmailzl</author>
    <author>Bastian Geißler</author>
    <author>Frederik Maiwald</author>
    <author>Tobias Laumer</author>
    <author>Michael Schmidt</author>
    <author>Stefan Hierl</author>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othpublikationsherkunft" number="">Externe Publikationen</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
    <collection role="institutes" number="">Labor Additive and Intelligent Manufacturing for Sustainability (AIMS)</collection>
  </doc>
  <doc>
    <id>966</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>965</pageFirst>
    <pageLast>975</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>bookpart</type>
    <publisherName>Verlag der Technischen Universität Graz</publisherName>
    <publisherPlace>Graz</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-30</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Potentials of the ALE-Method for Modeling Plastics Welding Processes, in Particular for the Quasi-Simultaneous Laser Transmission Welding</title>
    <abstract language="eng">The  Arbitrary-Lagrangian-Eulerian-Method  (ALE-Method) offers the  possibility to model the quasi-simultaneous laser transmission welding of plastics, in which a squeeze-flow of molten plastic occurs. It is of great interest to get a deeper understanding of the fluid-structure-interactions in the welding zone, since the occurring squeeze-flow transports heated material out of the joining zone, causinga temperature decrease inside.In addition, the numerical  modelling offers the possibility to investigate the flow conditions  in the joining zone. The aim of this article is to show the  potentials of the ALE-Method to simulatethe quasi-simultaneous laser transmission welding with the commercially available software LS-DYNA. The central challenge is to realize a bi-directionalthermo-mechanically coupled simulation,which considers the comparatively high thermal expansion and calculates the interactions of solid and melted plastic correctly. Finally, the potentials of the ALE element formulations for the mathematical description of welding processesare shown, especially for those with a squeeze-flow.</abstract>
    <parentTitle language="eng">Mathematical Modelling of Weld Phenomena 12</parentTitle>
    <identifier type="doi">10.3217/978-3-85125-615-4-51</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <enrichment key="ConferenceStatement">12th International Seminar ‘Numerical Analysis of Weldability‘, which was held from September 23 to 26, 2018, at Schloss Seggau near Graz, Austria</enrichment>
    <author>Anton Schmailzl</author>
    <author>Sven Hüntelmann</author>
    <author>Tobias Loose</author>
    <author>Johannes Käsbauer</author>
    <author>Frederik Maiwald</author>
    <author>Stefan Hierl</author>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>819</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>8</pageFirst>
    <pageLast>13</pageLast>
    <pageNumber/>
    <edition/>
    <issue>1</issue>
    <volume>Vol. 16</volume>
    <type>article</type>
    <publisherName>Japan Laser Processing Society</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-25</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Online pyrometry for weld seam localization in absorber-free laser transmission welding of transparent polymers</title>
    <abstract language="eng">Production of optical and medical devices makes high demands on cleanliness, precision, visual appearance and reliability. Advantages  of laser transmission welding – contactless input of energy, high  precision, no adhesives and no particle formation – can be fully  exploited for this use. For absorber-free welding, lasers emitting in the polymers’ intrinsic absorption spectrum between 1.6 μm and 2 μm are used. Focusing the laser beam with high NA provides large intensity gradients inside the specimen and enables selective fusing of the joining zone without affecting the surface. Since a molten  upper surface leads to visible and palpable irregularities and  causes warpage, the verticalexpansion of the weld seam is crucial. To meet the high quality and reliability required in the medical and optical  industry, online monitoring of the seam is necessary. The aim of  this  work is the localization and evaluation of the weld seam using pyrometry. First, the emitted thermal radiation is computed, enabling signal analysis regarding origin and spectrum. Thus, assessment of measurement spectrum and forecast of the signal in dependence on seam  shape and position is possible. Finally, welding tests with Topas 8007-04 are performed at 200 mm/s feed rate and monitored with 100 kHz. The comparison of tracked data with thin-cuts demonstrates that weld seam localization by pyrometry is possible, enabling online assessment of the process.</abstract>
    <parentTitle language="eng">Journal of Laser Micro/Nanoengineering</parentTitle>
    <identifier type="doi">10.2961/jlmn.2021.01.2002</identifier>
    <identifier type="issn">1880-0688</identifier>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <author>Frederik Maiwald</author>
    <author>Stephan Englmaier</author>
    <author>Stefan Hierl</author>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Laserdurchstrahlschweissen</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Kunststoff</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Transparenz</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Schweißnaht</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Wärmestrahlung</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Pyrometrie</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Prozessüberwachung</value>
    </subject>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="oaweg" number="">Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>827</id>
    <completedYear/>
    <publishedYear>2020</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName>Japan Laser Processing Society</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-25</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Online pyrometry for weld seam localization in absorber-free laser transmission welding of transparent polymers</title>
    <abstract language="eng">Optical and medical devices made of transparent polymers are gaining popularity because of its cost advantages. The manufacturing technology must be able to meet the high demands of these applications. Advantages of laser transmission welding – contactless input of energy, precision, no adhesives and no particle formation – can be exploited here. For absorber-free welding, lasers emitting in the polymers‘ intrinsic absorption spectrum are used. Focusing the laser beam with high NA enables selective fusing of the joining zone. Since a molten upper surface leads to visible and palpable irregularities, the lateral expansion of the weld seam is monitored in this work. Welding tests with 1 mm thick plates of COC are performed and monitored by pyrometry. Distances between seam and surface measured in thin cuts and are compared with the pyrometer signal. This shows that the localization of the weld seam is possible and proper and faulty parts can be distinguished by pyrometry.</abstract>
    <parentTitle language="deu">21st International Symposium on Laser Precision Microfabrication: Dresden, 26.06.2020</parentTitle>
    <identifier type="url">http://www.jlps.gr.jp/en/proc/lpm/20/073.pdf</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <author>Frederik Maiwald</author>
    <author>Stephan Englmaier</author>
    <author>Stefan Hierl</author>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Laserdurchstrahlschweissen</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Kunststoff</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Transparenz</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Schweißnaht</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Wärmestrahlung</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Pyrometrie</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Prozessüberwachung</value>
    </subject>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>892</id>
    <completedYear/>
    <publishedYear>2020</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>686</pageFirst>
    <pageLast>690</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>94</volume>
    <type>conferenceobject</type>
    <publisherName>Elsevier</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Absorber-free Laser Transmission Welding of Transparent Polymers using Fixed Focus Optics and 3D Laser Scanner</title>
    <abstract language="eng">Laser transmission welding is a well-known joining technology for thermoplastics, providing reliable and hermetical sealing without adhesives or particle formation. The main advantages of laser-based energy input - high precision, no additional adhesive and no particle emission - are essential for medical and optical applications. To obtain sufficient absorption in visually transparent polymers, thulium fibre lasers emitting in the polymers’ intrinsic absorption spectrum are used. Optics with high numerical aperture provide large intensity gradients inside the specimen, enabling selective fusing in the joining zone. Although the basic feasibility has already been demonstrated, the welding process lacks stability and productivity.&#13;
&#13;
Aim of this work is the determination of optimized settings for a fast and reliable welding process. Thus, the interplay of process parameters as well as their impact on the seam are analysed by thermal simulations. Calculated settings are verified by welding tests with COC, PA6 and PETG, using a fixed-focus optics and a 3D laser scanner with up to 200 mm/s feed rate.</abstract>
    <parentTitle language="eng">Procedia CIRP</parentTitle>
    <identifier type="doi">10.1016/j.procir.2020.09.117</identifier>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <enrichment key="ConferenceStatement">11th CIRP Conference on Photonic Technologies [LANE 2020] on September 7-10, 2020</enrichment>
    <licence>Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International</licence>
    <author>Frederik Maiwald</author>
    <author>Stephan Englmaier</author>
    <author>Stefan Hierl</author>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="oaweg" number="">Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>925</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>168</pageFirst>
    <pageLast>171</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName>pro Business GmbH</publisherName>
    <publisherPlace>Berlin</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-01-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Simulation of Pyrometer Based Temperature Measurement Systems using Non-Sequential Raytracing</title>
    <parentTitle language="eng">Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf</parentTitle>
    <enrichment key="opus.source">publish</enrichment>
    <author>Frederik Maiwald</author>
    <collection role="ddc" number="670">Industrielle Fertigung</collection>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>3242</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>11</pageLast>
    <pageNumber/>
    <edition/>
    <issue>5</issue>
    <volume>12</volume>
    <type>article</type>
    <publisherName>MPDI</publisherName>
    <publisherPlace>Basel</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Optical Coherence Tomography for 3D Weld Seam Localization in Absorber-Free Laser Transmission Welding</title>
    <abstract language="eng">Quality and reliability are of the utmost importance for manufacturing in the optical and medical industries. Absorber-free laser transmission welding enables the precise joining of identical polymers without additives or adhesives and is well-suited to meet the demands of the aforementioned industries. To attain sufficient absorption of laser energy without absorbent additives, thulium fiber lasers, which emit in the polymers’ intrinsic absorption spectrum, are used. Focusing the laser beam with a high numerical aperture provides significant intensity gradients inside the workpiece and enables selective fusing of the internal joining zone without affecting the surface of the device. Because seam size and position are crucial, the high-quality requirements demand internal weld seam monitoring. In this work, we propose a novel method to determine weld seam location and size using optical coherence tomography. Changes in optical material properties because of melting and re-solidification during welding allow for weld seam differentiation from the injection-molded base material. Automatic processing of the optical coherence tomography data enables the identification and measurement of the weld seam geometry. The results from our technique are consistent with microscopic images of microtome sections and demonstrate that weld seam localization in polyamide 6 is possible with an accuracy better than a tenth of a millimeter.</abstract>
    <parentTitle language="eng">Applied Sciences</parentTitle>
    <identifier type="doi">10.3390/app12052718</identifier>
    <note>Corresponding author: Frederik Maiwald</note>
    <enrichment key="opus.import.date">2022-03-20T14:33:49+00:00</enrichment>
    <enrichment key="opus.source">sword</enrichment>
    <enrichment key="opus.import.user">importuser</enrichment>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Frederik Maiwald</author>
    <author>Clemens Roider</author>
    <author>Michael Schmidt</author>
    <author>Stefan Hierl</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>image processing</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>laser transmission welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>optical coherence tomography</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>process monitoring</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>transparent polymers</value>
    </subject>
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    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>46</pageFirst>
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    <pageNumber/>
    <edition/>
    <issue>1</issue>
    <volume/>
    <type>article</type>
    <publisherName>DVS Media</publisherName>
    <publisherPlace>Düsseldorf</publisherPlace>
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    <title language="eng">Laser welding of polymer foils with spatially adapted intensity distributions</title>
    <abstract language="eng">Absorber-free laser transmission welding is characterized by its contactless energy input and geometricflexibility and enables the precise and clean joining of polymer films without absorbing additives or adhesives. It is therefore well suited for applications with high demands regarding process reliability and cleanliness such as packaging, fluid containersor as sealing film in medicaland food industry. A homogeneous weld seam temperature is necessary for a large processwindow. In this work, the naturally Gaussian-shaped intensity distributionof the laser beam is there foreconverted into a donut-shaped and a flat-top-shaped distribution. When using the donut-shape, the processwindow for welding polypropylene or polyethylene films is increased by up to a factor of 3. At the same time, the weld seam strength almost corresponds to the strength of the base material.</abstract>
    <parentTitle language="deu">Joining Plastics</parentTitle>
    <identifier type="doi">10.53192/JP20250146</identifier>
    <identifier type="issn">1864-3450</identifier>
    <enrichment key="opus.import.date">2025-01-20T09:16:32+00:00</enrichment>
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    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Frederik Maiwald</author>
    <author>Lea Kroth</author>
    <author>René Geiger</author>
    <author>Bernhard Schmitt</author>
    <author>Stefan Hierl</author>
    <author>Michael Schmidt</author>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Laserschweissen</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>swd</type>
      <value>Kunststofffolie</value>
    </subject>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
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  <doc>
    <id>5753</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
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    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue>Spring 2021</issue>
    <volume>50</volume>
    <type>article</type>
    <publisherName>Europa Science</publisherName>
    <publisherPlace>Cambridge</publisherPlace>
    <creatingCorporation/>
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    <completedDate>2023-01-03</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Absorber-free laser transmission welding of transparent polymers</title>
    <parentTitle language="eng">Laser Systems Europe</parentTitle>
    <identifier type="url">https://www.lasersystemseurope.com/analysis-opinion/absorber-free-laser-transmission-welding-transparent-polymers</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Frederik Maiwald</author>
    <author>Stefan Hierl</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Medical</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Fibre lasers</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Plastics</value>
    </subject>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
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  <doc>
    <id>8307</id>
    <completedYear/>
    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferencesummary</type>
    <publisherName>Japan Laser Processing Society</publisherName>
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    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">In-situ optical coherence tomography for spatio-temporal analysis of melt pool crystallization in absorber-free laser transmission welding of polymers</title>
    <parentTitle language="eng">The 9th International Congress on Laser Advanced Materials Processing (LAMP2025), Ise-city, Mie-prefecture, Japan, June 10 to June 13, 2025</parentTitle>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Frederik Maiwald</author>
    <author>Julian Schulze</author>
    <author>Michael Schmidt</author>
    <author>Stefan Hierl</author>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>7299</id>
    <completedYear/>
    <publishedYear>2024</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>489</pageFirst>
    <pageLast>493</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>124</volume>
    <type>conferenceobject</type>
    <publisherName>Elsevier</publisherName>
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    <completedDate>--</completedDate>
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    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Enlarging the process window in absorber-free laser transmission welding of polymer foils using tailored laser intensity distribution</title>
    <abstract language="eng">Absorber-free laser transmission welding enables precise and clean joining of polymer foils without absorbent additives or adhesives. It is well suited for applications in medical technology and food industry, which impose high demands on process reliability. To achieve a large process window and thus a reliable process, a homogeneous weld seam temperature is desirable. For this purpose, the intensity distribution of the laser beam is adapted locally by refractive beam shaping optics. Using a donut-shaped intensity distribution, the weld seam temperature is homogenized. Thus, the process window for welding polypropylene or polyethylene foils is enlarged up to a factor of 4 compared to a conventional, Gaussian-shaped distribution. This enables the reliable welding of even 85 µm thin foils, which could only be welded to a limited extent with a conventional laser intensity distribution.</abstract>
    <parentTitle language="deu">Procedia CIRP</parentTitle>
    <identifier type="doi">10.1016/j.procir.2024.08.159</identifier>
    <note>accepted by publisher</note>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <licence>Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International</licence>
    <author>Frederik Maiwald</author>
    <author>Lea Kroth</author>
    <author>Alexander Laskin</author>
    <author>Stefan Hierl</author>
    <author>Michael Schmidt</author>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="oaweg" number="">Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>7381</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>patent</type>
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    <creatingCorporation>Ostbayerische Technische Hochschule Regensburg</creatingCorporation>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2024-08-06</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Laser welding device for clamping and welding components and method for clamping and welding components</title>
    <identifier type="url">https://data.epo.org/publication-server/rest/v1.0/publication-dates/20230830/patents/EP4234213NWA1/document.pdf</identifier>
    <enrichment key="PatentNr">EP4234213A1</enrichment>
    <enrichment key="PatentLand">Deutschland</enrichment>
    <enrichment key="PatentYear">2022</enrichment>
    <enrichment key="PatentDate">28.02.2022</enrichment>
    <enrichment key="PatentZugriff">Mitgliedstaaten der EU</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <author>Frederik Maiwald</author>
    <author>Stefan Hierl</author>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="institutes" number="TCParsberg">Technologie-Campus Parsberg-Lupburg</collection>
    <collection role="institutes" number="">Labor Laser-Materialbearbeitung (LMP)</collection>
  </doc>
  <doc>
    <id>7999</id>
    <completedYear/>
    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
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    <type>conferenceobject</type>
    <publisherName>SPIE</publisherName>
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    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Optical coherence tomography for in situ weld seam monitoring in absorber-free laser transmission welding</title>
    <abstract language="eng">Optical and medical devices are frequently made of polymers and place high demands on precision, cleanliness, and reliability of the manufacturing processes used. Absorber-free laser transmission welding is well-suited for joining these devices: the energy input is contactless, no adhesives, additives, or absorbers are required, and the fiber lasers used enable precise weld seams. As the weld seam geometry is decisive for the joint strength and thus crucial for the quality of the product, the welding process is monitored in-situ using Optical Coherence Tomography (OCT). Subsequently, the weld seam geometry is identified automatically using the AI model "Segment Anything" (SAM), which performs semantic segmentation of the OCT data without requiring any training from the user. Welding tests using polyamide six indicate that the seam size is measured with an accuracy of a few hundredths of a millimeter, showing excellent agreement with microscopic images of microtome sections.</abstract>
    <parentTitle language="eng">Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXX, 25-31 January 2025, San Francisco, California, United States</parentTitle>
    <identifier type="doi">10.1117/12.3040607</identifier>
    <enrichment key="OtherSeries">Proceedings of SPIE ; 13350</enrichment>
    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Frederik Maiwald</author>
    <author>Fabian Fries</author>
    <author>Julian Schulze</author>
    <author>Petra Honnerová</author>
    <author>Stefan Hierl</author>
    <author>Michael Schmidt</author>
    <collection role="institutes" number="FAKMB">Fakultät Maschinenbau</collection>
    <collection role="othforschungsschwerpunkt" number="16316">Produktion und Systeme</collection>
    <collection role="DFGFachsystematik" number="1">Ingenieurwissenschaften</collection>
  </doc>
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