Study of the laser-material interaction for innovative hybrid structures: Thermo-mechanical characterization of polyethylene-based polymers (original) (raw)
Related papers
Investigating Thermal Interactions in the Case of Laser Assisted Joining of PMMA Plastic and Steel
Physics Procedia, 2014
Laser transmission joining of dissimilar materials is a novel and promising area of researches on joining technology. However, processes during laser assisted metal plastic (LAMP) joining are not completely explained yet. In the course of this study, the authors investigated the joining process of PMMA plastic and steel by means of laser, as a part of their research on dissimilar material joining. The characteristic process temperature was measured during the joining by different heating conditions, to describe thermal interactions between the polymer and the metal part, and to better understand the mechanism of joining.
Laser-Induced Crosslinking of Ultra-Low- and High-Density Polyethylene
Macromolecular Rapid Communications, 2007
The use of laser radiation to initiate the crosslinking process in ultra low-density polyethylene (ULDPE) and high-density polyethylene (HDPE) was evaluated. The process was found to be most effective for pulsed laser irradiation when the polymer was traced with a photoinitiator: 4-chlorobenzophenone (CBP). The gel content measurements proved that crosslinking took place in all the irradiated samples. The degree of crosslinking was measured for different values of irradiation energy, temperature, photoinitiator concentration and the nature and type of crosslinking agents. The effects of all these parameters on the degree of crosslinking and the consequent effects on mechanical properties of the polymers were analyzed. Also found in the present study is the fact that a better efficiency of crosslinking was achieved at longer laser irradiation wavelength. The ultimate tensile stress and elongation at fracture were measured for all cross-linked samples and compared with those of the controlled ones.
Hybrid metal-plastic joining by means of laser
International Journal of Material Forming, 2010
The growing need of lightweight components determined a large exploitation of non metallic materials such as polymers, fibres and elastomers in the industrial production with a consequent request of specifically optimized manufacturing processes. The high optimization demands in terms of cost, weight and productivity of the modern markets determined a growing interest towards hybrid components in which two or more different materials coexist in order to achieve specifically optimized characteristics. According to these considerations the work proposed in this article is aimed at experimentally evaluate the feasibility of joining processes between metal and plastic components by means of the exploitation of a laser source. The metallic material involved in the experimental trials is AISI 304 stainless steel joined in an overlapping configuration with several different polymers: PA66, glass fibre reinforced PA66, carbon fibre reinforced PA66. The laser source involved in this activity was a 100 W CW diode source equipped with a three axis cell. In order to evaluate the results of the joining process a tensile test was carried out on the obtained specimens.
Laser Transmission Welding of Semi-Crystalline Polymers and Their Composites: A Critical Review
Polymers
The present review provides an overview of the current status and future perspectives of one of the smart manufacturing techniques of Industry 4.0, laser transmission welding (LTW) of semi-crystalline (SC) polymers and their composites. It is one of the most versatile techniques used to join polymeric components with varying thickness and configuration using a laser source. This article focuses on various parameters and phenomena such as inter-diffusion and microstructural changes that occur due to the laser interaction with SC polymers (specifically polypropylene). The effect of carbon black (size, shape, structure, thermal conductivity, dispersion, distribution, etc.) in the laser absorptive part and nucleating agent in the laser transmissive part and its processing conditions impacting the weld strength is discussed in detail. Among the laser parameters, laser power, scanning speed and clamping pressure are considered to be the most critical. This review also highlights innovativ...
Hybrid Joining of Steel and Plastic Materials by Laser Beam
TRANSPORT, 2013
Hybrid joining of metals and plastics in order to produce lightweight parts is of growing interest in the manufacturing processes of vehicles, electrical devices and biomedical applications. In this study, the joining of PMMA plastic (poly methyl metacrylate) and unalloyed steel were investigated by the authors. The authors successfully joined PMMA and steel by means of Nd:YAG laser and carried out tensile tests to measure the joining strength. Experimental results showed that the joint strength is influenced by the heating time, the penetration depth of the steel workpieces in the plastic, by the surface roughness of steel and by the time elapsed between bonding and tearing of the samples.
Optics & Laser Technology, 2017
Laser-Assisted Direct Joining (LADJ) has been employed for a wide variety of materials including metals, thermoplastics and reinforced thermoplastics. The feasibility of Laser-Assisted Direct Joining (LADJ) of Carbon Fibre Reinforced Polymer (CFRP) with thermosetting matrix to polycarbonate sheets is investigated in this work. The process was performed by means of a high-power diode laser with a maximum power of 200 W. Experimental tests were carried out by varying the main process conditions including the laser power and scanning speed. Morphological analysis using Optical and Scanning Electron Microscopy (SEM) as well as mechanical characterization of the welds were performed to understand the influence of the processing conditions on the weld quality, defects, and strength. Preliminary results have been encouraging: the process consists in removing the exterior epoxy layer from the CFRP and the adhesion of the carbon fibres to the PC. According to the achieved findings, the mechanical strength of the welds was highly affected by the Linear Energy Density (LE): low values of LE resulted in poor adhesion of the polycarbonate through the carbon fibres, which led to poor mechanical fastening and adhesion. On the other hand, processing conditions leading to excessive values of LE resulted in considerable damage of the composite matrix (the epoxy resin underlying the exposed carbon-fibre layer) and formation of bubbles on the PC substrate, which produced a dramatic reduction of the mechanical behaviour of the welds. The apparent shear strength, calculated as the ultimate shear force by the effective adhesion area was 8.4 MPa.
Mechanical performance of single lap polymeric joints welded by a portable diode laser
2015
The polymer laser welding can be successfully used to join two or more parts of plastic surfaces and it can be used in several fields, such as the biomaterials and microelectronics. Thermoplastic materials are welded by a localized energy input without the use of any organic solvents and formation of particulate.The employment of a portable diode laser can personalize the welding joint area and it let to draw the welding geometry, like a pen in a very easy and fast process. In this research, we studied single lap joints made by biomedical grade polyethylene (UHMWPE) pure and filled with carbon nanomaterials, necessary to make the polymer laser absorbent, added in amount of 0,2% in weight.The joints were irradiated by a diode laser operating at 970 nm (fundamental harmonic), in repetition rate of 10Hz, with a maximum pulse energy of 200 mJ and a laser spot of . 4 mm2 (no focusing lens were employed). The portable laser was employed to realize four types of welding geometries (points,...
Laser Transmission Welding of Thermoplastic: Experimental Investigation Using Polycarbonate
Advanced Materials Research, 2015
The use of lasers for joining plastics is growing. Several different approaches are being developed for laser welding of plastics. The main principle now used to laser-weld plastics is known as “transmission welding.” Transmission welding has demonstrated that precise, controllable heating and melting of low melting point thermoplastics can be produced at the interface between a transmissive and an absorptive plastic. [1-8]
Lasers in Manufacturing and Materials Processing, 2024
The study of energy fractions plays a fundamental role in laser joining operations: from their knowledge, it is possible to calculate the amount of laser beam energy that is effectively available during the formation of chemical and physical bonds, and how much energy is dissipated. This study examines semi-crystalline polymers of polyamide 6.6 (PA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polypropylene (PP), semitransparent to light radiation, with the aim of studying the influence of surface roughness on the distribution of energy fractions, and in particular on the reflection portion. For this purpose, polymeric samples with different surface finishing were prepared and characterized by profilometric analysis. Subsequently, an experimental setup was implemented to directly measure the transmitted ratio, obtaining the reflected energy fraction from the Beer-Lambert law, and the absorbed ratio by energy balance. The results showed a decrease in the power transmitted by polymers subjected to surface treatment, due to an increase in the reflection fraction, a phenomenon particularly evident for PET, for which the reflection share increased from ~ 0.5% to ~ 15.3%, following P240 treatment. A lower influence was verified for PA and especially PTFE, due to a lower influence of the treatment on surface morphology. On the basis of the experimental results, it is hypothesised that roughening the lower section of the irradiated polymer could allow an increase in the total internal reflection fraction, favouring the joint at the interface point.