Laser Welding Of Polymers Research Articles

Recent advances in laser welding for joining polymeric components

Laser welding of polymers is a very popular industrial joining process, creating joints with good mechanical performance. However, the implementation of optimized laser welding processes is still quite limited since most industrial applications adopt an empirical approach to adjust the process parameters. The current work provides a summary of new findings on the subject of laser joining of polymers, describing the key operation modes of this joining method, its process parameters and how they affect the joint characteristics. The response of polymers to temperatures generated during laser welding is also discussed, as well as the effect of additives on the weldability of polymers.

Laser polymer welding process: Fundamentals and advancements

Laser polymer welding provides a feasible alternative where traditional polymer joining processes have reached their limits. The flexibility of this process is unparalleled, and the weld quality is superior to that of most traditional polymer joining processes. A variety of laser irradiation techniques are devised and effectively utilized in laser welding of polymers. The polymer compositions, as well as optical and thermal characteristics, are significant factors influencing the laser polymer welding process. For a wide variety of polymers, laser polymer welding produces weld strength equivalent to the strength of the substrate material. Lasers are utilized for more than only polymer welding; they are also used to weld hybrid structures consisting of polymer-metal, polymer-ceramics, polymer-glass, polymer-wood composites, etc. This paper presents an overview of the process fundamentals and advancements in laser polymer welding process.

Modeling of thermal processes in laser welding of polymers

The Paton Welding Journal, 2021, №11. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Correlation between weld seam morphology and mechanical properties in laser transmission welding of polypropylene

In laser welding of polymers, the morphology of weld seams is decisive for the weld strength. Usually, time consuming parameter screening with subsequent destructive tests are performed in order to find suitable process parameter sets resulting in strong weld seams. For more effective and flexible process development, non-destructive characterization methods which base on, for example, crystal structure detection in the welding zone require a deep understanding of interrelations between weld seam morphology and strength.Therefore, polypropylene samples welded overlapping are analysed regarding crystal structure in the heat-affected zones by microscope before and after tensile testing is used to quantify the weld strength. Experimental results show that there is an almost linear relationship between the increase in force and the cross-sectional area of weld seams in the absorption joining partner. Moreover, it is shown that thermal FE simulations allow the prediction of the size of the heat affected zone, which strongly influences the crystal structures inside the weld.

Multiaxial loading of thermoplastic laser welds

The number of laser welded applications in industry is rising steadily. For example, laser welding of polymers is used in the automotive, household and medical sectors. In these areas, a high focus on long-term durability and reliability of laser welds is required. The laser welds are exposed to several types of loading, such as ambient conditions, variable amplitude loading and multiaxial loading. Multiaxial loading causes a multiaxial stress state in the laser weld line. However, the determination of such multiaxial stress states presents a challenge. The interactions of different types of loading, such as tension, torsion and in or out of plane loading, especially for cyclic loading, have not yet been examined comprehensively. Test specimens for determining the influence of such parameters on long-term durability of laser welds are not widely available. This paper presents the results for multiaxial loading on thermoplastic laser welds. Therefore, the MultiWeldTester is used. The MultiWeldTester is loaded with constant amplitudes for tension and torsion in plane and out of plane. The analysis of the hysteresis data of these tests leads to conclusions about the interactions on the fatigue behaviour.

Laser Welding of Transparent Polymers by Using Quasi-simultaneous Beam Off-setting Scanning Technique

Traditionally laser polymer welding has been done by using lasers with wavelength of c. 1μm wavelength. With this wavelength one of the pair of polymers to be joined needs to be transparent and one absorbing, usually clear and black, respectively. Joining of two transparent polymers with laser has been possible only by using absorbing additive between the samples or by doping the polymer with absorbing additive. During the last years lasers with new wavelengths between 1.4 to 2μm have been developed. With this wavelength range welding of the transparent polymer to another transparent one without any absorbing additives is now possible. In this paper joining of transparent to transparent polymers with quasi-simultaneous laser welding (QSLW) technique and fibre lase with wavelength of 1.94μm is studied. Also a new scanning technique for QSLW is introduced. In this technique laser beam path is off-setting to a different place in every scanning round. This way the Gaussian beam shape of fibre laser can be smoothened to be more suitable for polymer welding and more flexibility on laser welding of polymers is achieved without losing the benefits of quasi-simultaneous laser welding.

Possibilities of Laser Processing of Paper Materials

Nowadays, lasers are applied in many industrial processes: the most developed technologies include such processes as laser welding, hybrid welding, laser cutting of steel, etc. In addition to laser processing of metallic materials, there are also many industrial applications of laser processing of non-metallic materials, like laser welding of polymers, laser marking of glass and laser cutting of wood-based materials. It is commonly known that laser beam is suitable for cutting of paper materials as well as all natural wood-fiber based materials. This study reveals the potential and gives overview of laser application in processing of paper materials.In 1990's laser technology increased its volume in papermaking industry; lasers at paper industry gained acceptance for different perforating and scoring applications. Nowadays, with reduction in the cost of equipment and development of laser technology (especially development of CO2 technology), laser processing of paper material has started to become more widely used and more efficient. However, there exists quite little published research results and reviews about laser processing of paper materials. In addition, forest industry products with pulp and paper products in particular are among major contributors for the Finnish economy with 20% share of total exports in the year 2013. This has been the standpoint of view and motivation for writing this literature review article: when there exists more published research work, knowledge of laser technology can be increased to apply it for processing of paper materials.

Laser Welding of Polymers

AbstractFor many applications especially in electronics laser welding but also in medical device manufacturing is the dominating joining technology. The main advantages are the non‐contact and vibration‐free energy input, the precise control of the deposited energy and thus the related reproducibility and low thermal load of the parts. The decreasing costs for laser source and beam guiding system are enhancing these advantages and make laser welding even more competitive compared to other joining technologies.

Extending the Limits of Laser Polymer Welding using Advanced Irradiation Strategies

After enjoying a significantly increased industrial acceptance, mainly due to the development of high power diode lasers, the laser polymer welding has faced extensive investigation over the last decade in order to become nowadays a strong competitor for the other polymer joining processes. The latest developments in the field of laser materials processing such as laser sources with excellent beam quality are bringing new opportunities and also challenges for the laser welding of polymers and lead to a further extension of the process limits. This paper presents the achieved results for the polymer welding using high brilliance laser sources together with advanced irradiation strategies based on the local und temporal modulation of the laser beam such as the recently developed method called TWIST ® – Transmission Welding by an Incremental Scanning Technique. This approach leads to an optimized thermal management within the welding zone, an exact control of the temperature field generated by the absorbed laser energy, and a significant increase of process robustness, welding quality, process flexibility and efficiency. Experimental results for welding of polymers with a weld seam width from 100 µm up to 800 µm and a processing speed up to 30 m/ min are presented and discussed.

Laser welding of polymers

AbstractDeep penetration welding and cutting of metals can be carried out at high speed with relatively low laser power. The efficient coupling of the laser radiation to the metal is due to the formation of a “keyhole.” Over the years, an attempt has been made to transfer the results on metals to plastics. It will be shown here that keyhole welding of plastics is limited to the very restricted set of plastics that have a boiling point. Volume heating, a mechanism that is not applicable to metals, is restricted to plastics with a good transparency for the incident radiation and with a high optical quality. Finally, surface heating is shown to be the most common mechanism for heating plastics.

CO2 laser welding of polymers

AbstractDeep penetration welding of polymers can be carried out at high speed with relatively low laser power. This results from an efficient coupling CO2 laser radiation to polymers that leads to volume heating. A brief review of energy coupling and heat transfer effects in polymers under CO2 laser welding conditions is given. Some examples of low power (10 to 100 watt) CO2 welding of polypropylene and polyethylene at depths of up to 1.5 cm are discussed.