Final Report Summary - POLYBRIGHT (Extending the process limits of laser polymer welding with high-brilliance beam sources)
Executive Summary:
Plastics play an important role in our lives, with a wide array of products such as everyday packaging, furniture and building materials, and high tech products in the automotive, electronics, aerospace, white goods, medical and other sectors. Today, advanced plastic polymers have already replaced other materials in the manufacturing, optical and electronics industry, and have driven drastic changes in the design and set up of almost all products in terms of weight reduction, cost saving and environmental impact. These are crucial factors for the success of both disposable and long lasting products in manufacturing and use.
The aim of PolyBright is to provide high speed and flexible laser manufacturing technologies required for the mass production of complex plastics parts, and to expand the limits of current plastic part assembly. New laser polymer joining processes for optimized thermal management in combination with wavelength adapted polymers and additives will provide higher quality, high processing speeds of up to 1 m/s and robust manufacturing processes at lower costs in order to meet future industries’ needs for speed, flexibility and quality of welding geometries. Key innovations of the PolyBright project are high brilliance mid-IR-wavelength fiber and diode lasers with powers up to 500 W, high speed scanning, and flexible beam manipulation systems such as dynamic masks and scanning heads with multi-kHz scanning speeds.
Project Context and Objectives:
Plastics play an increasingly important role in all aspects of everyday life, with a wide array of products such as packaging, furniture and building materials, and high tech products in the automotive, electronics, aerospace, white goods, medical and other industrial sectors. Polymeric materials have a vast potential for new exciting applications in many areas such as conduction and storage of electricity, heat and light; molecular based information storage and processing; molecular composites; unique separation membranes, new forms of food processing and packaging; medical devices; and housing and transportation. Today, advanced plastic polymers have already replaced other materials in the manufacturing, optical and electronics industry, and have driven drastic changes in the design and setup of almost all products in terms of weight reduction, cost saving and environmental impact. These are crucial factors for the success of both disposable and long lasting products for manufacturing and use. The large number of current and future applications of polymers has created the need to improve joining techniques for processing of polymeric materials. PolyBright addressed this need by advancing existing and developing new processes for laser welding of polymers.
The Idea | The initial objectives of PolyBright were to provide high speed and flexible laser manufacturing technologies required for the mass production of complex plastics parts, and to expand the possibilities of plastic part assembly. Furthermore, PolyBright objectives were to (1) improve existing welding techniques and overcome current limitations, (2) develop high brilliance laser sources in the higher NIR wavelength range which allow welding of polymeric materials without the need for IR absorbers or other additives, and (3) increase the process robustness and cycle times to ensure high manufacturing quality. New laser polymer joining processes for optimized thermal management in combination with wavelength adapted polymers and additives provide higher quality, high processing speeds of up to 1 m/s and robust manufacturing processes at lower costs in order to meet future industries’ needs for speed, flexibility and quality of welding geometries. Key innovations of the PolyBright project are high brilliance mid-IR-wavelength fiber and diode lasers with powers up to 500 W, high speed scanning, and flexible beam manipulation systems such as dynamic masks and scanning heads with multi-kHz scanning speeds.
Several European companies in the automotive, white goods and medical device industrial sectors, among other academic and SME partners, were involved in PolyBright. Their involvement was driven by the interest to implement laser welding techniques for relevant polymeric products in the production lines. These companies identified a range of products which highlight the advantages of this new joining technique.
Material Choice | Material requirements such as color (pigments, colorants) and the use of IR absorbers or various additives vary between industrial sectors. One of the objectives of PolyBright was to broaden the range of polymer materials and material combinations that are suitable for laser welding. The choice of material depends on the physical and chemical characteristics of the polymer and its intended use. Different material properties such as melting point, aliphatic/aromatic structure, and flexibility define the usability of the polymer for specific applications as well as its laser weldability. Adding fillers such as glass fibers or other inorganic fillers (e.g. talc) modifies the characteristics of the polymer. A high amount of glass fiber presents a challenge for laser welding due to the strong scattering effect on the laser beam. IR additives enhancing the absorption of laser energy in the polymer are for example Lumogen® IR and Pro-Jet™. Material families that were studied in PolyBright include polyolefins (PP, PE), styrenic copolymers (ABS, SAN), polyamides (PA6, PA66, PA11), and thermoplastic elastomers (PPA, PEBAX). Welding of white components, one of the biggest challenges in laser welding of polymers was achieved within PolyBright. Newly developed laser systems allow for a significant increase in the number of suitable color combinations.
Adapted Laser Sources | Various new laser systems were developed within PolyBright. For the development of a diode laser system, a laser module with 80W output power at a wavelength of 980nm and an M-shaped intensity distribution was assembled. Other systems are also available at higher wavelengths in the NIR (1550nm, 1650nm and 1940nm). Higher laser output powers were achieved through a combination of several laser diodes, the number of which is limited by the fiber core diameter and its numerical aperture. For laser welding of polymers withouth additives a specific high-brilliance fiber laser was developed within PolyBright. For this system, the fiber laser was doped with Erbium instead of Ytterbium which is the standard for industrial fiber lasers used for cutting and metal welding. The Erbium doped fiber results in a laser wavelength around 1.5µm which is suitable for welding or polymeric materials. The ELS-500 is a fiber laser system with a maximum output power of 500W emitting at 1567nm. Improved welding of polymers is possible by modifying the intensity distribution of diode lasers with specific optical elements. Suitable micro optics for use as beam shaping elements fot the high power diode lasers were designed and produced. A special bi-shape lens was developed for the transformation of the intensity profile into a so-called M-shape distribution. In addition, a concept for a system with selectable wavelengths between 1.5-2µm was developed.
Machine Concepts | New machinery was needed to combine the newly developed high brilliance laser sources, new optics and scanning technologies for laser welding of polymers. Three different prototypes were developed and set up in PolyBright: (1) Quasi-simultaneous laser welding machine prototype with additional xyz axes, (2) TWIST welding machine prototype with a laser source at 1.5µm, and (3) dynamic mask welding machine prototype in combination with a galvo scanner. (1) The Cencorp 1300 Offline QS prototype machine features the following properties and components: offline workstation, class 1 laser product, 1330x1440x1770mm (LxDxH), 1300kg, axis movement: x 744mm y 800mm z 200mm with Beckhoff motion control, OS: Windows 7, user interface: Cencorp custom solution, electrical power supply: 400V 3phase 50Hz 16A, pressured air supply for clamping unit, connection for fume extraction, ethernet connection. (2) The ILT TWIST welding prototype machine was set up with the following properties and components: Fiber Rhino 8.5 scanner (Arges), InScript scanner control software (Arges), focussing lens S4LFT 1330/008 (f=342mm, focus diameter 130µm, field 215x215mm), laser ELR120SMWC (IPG) (power 120W, wavelength 1567nm, beam diameter 5.5mm) special design clamping (ILT), manual loading, machine housing: special design (INTRO, ILT). (3) The Leister dynamic mask prototype machine includes the following properties and components: fiber laser 1070nm, variable beam shape for contour or highly variable simultaneous welding, laser power up to 100W (unpolarized), LCoS 600x800px, ethernet IP data interface, customer specific controller (ethercat), pilot laser <1mW, line voltage 200/230V, frequency 50/60Hz, 16A max. current consumption, compressed air connection 6x10^5Pa, air cooled (exhaust air max. 55°C), operable in 1540°C, 860x1240x1860mm (LxDxH), 400kg, laser class 1 (2M with aiming laser).
Industrial Applications | In virtually all areas of medicine, increasingly sophisticated devices are combined with increasingly advanced materials to solve the most challenging technical problems. From functionalities such as sterility and biocompatibility to active drug delivery and conductivity, polymers prove to be more versatile and complex than ever before. Advanced polymer research is leading to new and innovative medical devices. Areas with the highest potential appear to be tissue engineering and transplant medicine, devices delivering pharmaceuticals, and specialized polymer coatings. For this reason, Coloplast, an international company that develops, manufactures and markets medical devices and services related to ostomy, urology, continence and wound treatment now benefits from new welding techniques for advanced polymers. For Coloplast, laser welding is an attractive alternative to heat sealing, to date the most commonly used welding principle in the company. Laser welding is fast and enables designs that are not feasible with other joining techniques
Electrolux is a manufacturer of home and professional appliances and the second largest appliance manufacturer in the world. It sells more than 40 Mio products to customers in 150 countries annually. Electrolux products include refrigerators, dishwashers, washing machines, vacuum cleaners and cookers. Investigations in new materials, material combinations and possible joining techniques to enhance the asthetics of white goods products has led Electrolux to test laser welding as a new opportunity for improved design and quality of assemblies. The selected test case involves washing group tubs which are currently hotplate or vibration welded. This test case offers a complex shape geometry and complex material requirements. A suite of welding tests at 1567nm with different PCbased compounds (opaque white and grey) was realized to select the appropriate material. Optimal joint configuration, the most suitable laser source and welding process parameters were chosen according to design requirements.
The automotive sector is continuously changing due to challenging markets in a capitalintensive industry, declining consumer confidence and increased regulation. The combination of these new realities has resulted in the need to produce new materials and lightweight structural elements to satisfy the demand for cleaner and greener cars. Much of the recent research and innovation were aimed at replacing classical steel parts with lighter materials such as highperformance and ultraperformance plastics in virtually every major system in today's vehicles. The new materials increase mechanical performance and component efficiency to meet the challenges of rising costs, reduced weight and changing regulatory standards. This also involves the increase of automation in production lines. For this reason CRF and Industria INAUXA are interesed in the development of new polymer joining techniques such as laser welding. CRF carried out various tests for lighting systems and under hood components, e.g. a fuel filter housing. These tests showed that laser welding is competitive in terms of weld quality and cycle time, especially for the combination of dissimilar materials such as PP and PA66. For another industrial test case, CRF chose the dashboard cluster of the Alfa Romeo Giulietta. The materials that were used include PMMA and black ABS for the instrument cover and the housing. The components are currently designed for ultrasonic welding. INAUXA performed several welding tests and decided to evaluate the advantages of the laser welding technique for stabilizer links connecting opposite (left/right) wheels together through short lever arms linked by a torsion spring. They increase the suspension's roll stiffness, i.e. its resistance to roll in turns, independent of its spring rate in the vertical direction. There are different models of stabilizer links, but all of them are made of PA66 with and without fiber glass. The percentage of fibers in the parts depends on the end user. INAUXA modified the material combination to achieve laser welding feasibility and was successful in fixing the PA66 ball race (white) to the PA66 housing (black) by using a diode laser.
Over the entire duration of the PolyBright project, the consortium worked together in a highly collaborative and well-organized fashion. The project was focused on the development of novel polymeric materials, new laser sources and optics, and innovative laser welding machines, with a special emphasis on collaboration between those partners validating the newly developed technologies through the industrial applications in the automotive, white goods and medical sectors. All test cases have shown that laser welding of polymers is feasible and comparable with established joining techniques in terms of productivity, quality, cycle time and process robustness. Specific highlights for each technical work package and the main achievements are summarized in section 1.3.
Project Results:
Figure 3 shows an overview of the interactions and dependencies among the different work packages within PolyBright. The project was well set up and organized to achieve all targeted objectives. The following pages summarize the main project results and the gain in knowledge and technological progress achieved throughout the project.
WP1: Specifications and user requirements
In WP1 all objectives were achieved. The products, materials, processes, additives to be manufactured in the PolyBright project were specified and defined.
The products and basic test samples demonstrated the capabilities of high power high brilliance lasers with new wavelengths between 1500 and 1900 nm which were adapted to the absorption properties of polymers. LIMO developed novel high brightness diode lasers at 1.7 – 1.9 µm wavelength plus novel beam shaping devices in order to improve the business case for laser processing of thermoplastics. Additives and colorants were added according of the needs of the end users. These additives were well suited for transforming a non-absorbing resin into an absorbing one and achieve aesthetical end user requirements.
ELUX as one of the project end users analysed, selected and defined some possible test cases belonging to the sector (as washing group tubs, handles, control panels) for the application and validation of the Polybright technology. A dedicated document was written for illustrating and explaining the user requirements for these applications. Moreover, a specific matrix was filled-in for describing and applying within the project the testing procedures for welding specimens.
Different welding processes developed in Polybright were validated, and different kinds of tests were carried out by the PolyBright partners in the different project phases to ensure the best welding quality. All milestones and deliverables were submitted.
WP2: Development of high brilliance laser sources
One of the main highlights of WP2 was the development and production of three high brilliance fiber laser sources according to the PolyBright Description of Work:
- ELR-120-Polybright, 120 W Erbium doped fiber laser with 1567 nm wavelength and single mode beam quality
- TLR-120-Polybright, 120 W Thulium doped fiber laser with 1940 nm wavelength and single mode beam quality
- ELS-500-Polybright, 500 W Erbium doped fiber laser with 1567 nm wavelength, 200 µm feeding fiber core diameter and multi mode beam quality providing beam with top hat distribution
Optical and electrical properties were characterized and input for beam shaping optics was generated.
Refractive micro optics for laser beam collimation and beam shaping were designed and fabricated.
Besides high brilliance fiber lasers, WP2 focused on developing and setting up fiber-coupled diode laser systems with new wavelengths in the far-infrared spectral range between 1500 and 1900 nm. All these diode lasers are coupled into a 400 µm diameter fibre core (numerical aperture NA=0.22) and deliver output power up to 80 W. In addition, a laser module with 80W output power at a wavelength of 980nm and an M-shaped intensity distribution was assembled.
WP3: High speed scanning and product specific beam shaping
In laser polymer welding, a rapid and robust welding process is essential. This need was faced in WP3. Fused-silica mirrors in two different scanning systems were replaced by silicon carbide mirrors resulting in a remarkable speed improvement of laser beam deflection. One of these systems is a 2D scanner featuring an f-theta lens whereas the other one is based on a f-theta-less 3D approach featuring a focus translation stage at the scanner’s input aperture. In addition to the replacement of the mirrors, the optical elements of both systems were adapted to wavelengths in the range between 1.5 up to 2 m.
Refractive and diffractive beam shaping techniques were developed and applied in order to achieve a wider process window and a more stable welding process. The improvement was based on the generation of a so-called “M-shaped” intensity spot profile resulting in a homogeneous temperature distribution across the seam during welding. Furthermore, the diffractive beam shaping technique was extended to constructing, setting up and testing a highly-variable beam shaping tool by implementating a phase modulator array, i.e.a liquid-crystal-on-silicon (LCoS) display, operated in reflection With this prototype machine, which was exhibitied during the K2013 fair in Düsseldorf, simultaneous laser welding can be extended considerably. Current limitations due to a high effort for changing the weld contour can be completely avoided by this technique. Key elements are the LCoS reflection device as well as polarized 1060 nm fiber laser radiation with 100 Watt maximum output power.
By shaping a high-brilliance fiber laser beam to a very well collimated laser line, a very precise mask welding system was developed allowing weld resolution in the range of 50 m which is a substantial progress compared to generating line beams from low-brightness diode laser beam sources Herein, a copper mask especially designed for high laser power density was applied.
WP4: Flexible, robust and fast-adapting laser beam welding
WP4 deals with the laser welding process itself with special respect to the welding method, heat transfer considerations and process-related geometrical aspects. A computer model based on heat conduction as well as polymer laser beam scattering yields temperature distributions which are in good accordance with microtome slice cuts of laser welded flat samples, particularly for applying the TWIST welding method to homogenise the heat affected zone.
It has been proven that TWIST welding enlarges the process window and increases polymer laser welding applicability using fiber laser in addition to diode laser radiation (see Figure 8, right).
The remote welding opportunities are increased due to the use of high-brightness fiber laser radiation and scanner lenses with long focal lengths. With two scanners, a so-called dual-head configuration was set up and was able to weld 400x400mm polymer plates. Furthermore, a highly variable clamping concept, based on a pressure chamber together with an elastic transparent foil was constructed, set up and tested as a prototype.
For high speed quasi-simultaneous laser welding around 10m/s, software was developed to smooth the energy input along the weld contour (Figure 9).
This is difficult to achieve at high speed in sharp corners, but was solved by developing an Intelligent Power Control (IPC) software to adapt the laser power cycle by cycle.
For one-shot welding, diffractive optical elements (DOEs) were manufactured and irradiated by pulsed laser radiation to generate shaped (square) contours. Another application for these DOEs is to transform a Gaussian laser beam intensity distribution into tophat shape or M-shape which was shown to improve energy input homogenisation (see Figure 10).
Besides 1µm wavelength which was used for regular polymer overlap welding, fiber lasers with 1.94 µm were developed to ensure polymer butt welding capability. This configuration needs optical penetration depths of both partners in the mm range.
Mask welding with line beam-shaped fiber laser radiation is advantageous to using line beam-shaped diode laser radiation, because a high spatial resolution can be achieved even at large distances between mask and work piece due to fiber lasers’ high brightness character (see Figure 13).
An important WP4 Highlight was the construction, key element selection and setup of a dynamic mask machine. This prototype allows highly flexible beam shaping for contour welding as well as highly flexible contour shaping for one-shot simultaneous welding. Key element is a Liquid Crystal on Silicon (LCoS) reflective mirror (details see Figure 14).
WP5: New machines for cost effective manufacturing with increased reliability
The main highlight of WP5 was the build-up of three laser system prototype machines for the welding of polymer materials:
- FhG-ILT’s TWIST welding machine prototype at 1.5μm
- Leister’s dynamic mask prototype machine in combination with a galvo scanner
- Cencorp’s quasi-simultaneous welding machine prototype with additional xyz axes
These prototype machines were developed on the basis of high-brilliance beam sources and welding processes developed within the project. Processes included for example optimized beam intensity profiles and optimized beam oscillation patterns for polymer materials. Prototype machines and welding processes were tested with real polymer products from the automotive, medical and white good sectors. In the white goods sector, the TWIST prototype machine was tested on washing machine door handle parts. In the automotive sector, the dynamic mask and QSLW machines were used for welding stabiliser links, meter frames and windows.
The prototype machine using dynamic mask welding combines a scanning system with the dynamic mask technology. Hardware and software were adapted to the workstation with the LCoS technology at Leister. The machine was presented during the K-Fair in Düsseldorf in October 2013.
To complement the activities of WP5, a flexible clamping device, easily adapted to different component geometries to be welded and an appropriate fixture to perform the welding test campaign on the selected test case (washing machine handle) was realised.
Moreover an evaluation of the final prototype system functionalities was carried out in relation to the white goods sector applications. In particular, the assessment was focused on estimating hypothetical real working environment conditions to validate the welding process cycle time and the capacity of the system to deal with mass production volumes as required by the sector/end user.
In total six experimental system setups were built out of which the three above mentioned experimental setups (TWIST welding, dynamic mask welding, QSLW) were selected for the built up of the three laser machine prototypes. The six experimental setups were:
- High resolution mask welding
- Dynamic mask welding
- DOE for beam shaping in scanning system
- Remote welding
- Quasi-simultaneous welding
- TWIST
WP6: Advanced materials, additives and product design for high speed welding
WP6 has given a very good experimental background for understanding the effect of absorbers, colours and laser wavelengths on partners’ welding ability. This background resulted in guidelines for users of the laser welding process. WP6 demonstrated the interest of using higher wavelength laser sources for laser welding of challenging material combinations, for instance transparent on transparent (low laser absorption) and white on white (high laser reflection). In WP6, new IR absorbers were tested and one in particular enabled significant cost savings for project partner Colopast. WP6 has also given interesting insights into computer simulation of mechanical resistance of welded samples, an important task for quality control and assurance. One of these simulation tools, based on ARMINES ARCAN mechanical test, can be used to design complex welding structures as the results do not depend on the system geometry. Results from WP6 have formed the basis for the work in WP8 and the demonstrators.
WP6 partner Treffert produced compounds of material, either unfilled or with additivies such as carbon black (CB) or different colorants. Partners Arkema and FhG-LBF worked on the selection process of the polymer materials and IR absorbers to be tested considering the material requirements of all partners. In addition, several injection campaigns were carried out to produce test samples for mechanical characterization (overlapped joint specimen, T-shape specimen, example see Figure 18).
WP6 carried out various measurements for each tested polymer material, such as specific heat tests, polymer density tests as a function of temperature, fatigue tests (Figure 19) and static tension tests. Optical properties of the materials were also measured (Figure 20). Static tension tests were carried out for overlapped joint and T-shape specimen, and fatigue tests were performed on notched and unnotched samples. Finite element calculations were performed to determine the highly stressed material volume of the laser welded samples. In addition, overmolding experiments were performed (by co-injection molding) to evaluate the weldability of all material combinations (see Figure 21).
The end users in the project, Electrolux and Coloplast, provided context information about the required polymeric materials for their use, and contributed to the definition of suitable and promising solutions to be applied and tested for laser welding. Welding trials with different absorbing and transparent part combinations were carried out at Coloplast (Figure 22).
WP7: Quality assurance and process control for zero failure manufacturing
The objective of WP7 was to develop quality assuarance strategies. This was accomplished using cameras, pyrometers and high speed thermal imaging. Mechanical testing of welded samples was also a part of quality assurance. Pyrometers were used as reference since they are already used in the industry. High speed thermal imaging was seen as a viable option for R&D activities but their speed and sensivity are not high enough for online control and thus for industrial application. Camera positioning is useful in many cases if part positioning needs to be corrected or tracked. The Global Supervision System (GSS) developed within the project showed good potential of camera-based positioning system capabilities. Mechanical testing of welded samples gave a good insight into weld properties. Signal analysis and the developed methods were seen as a very powerful method for defect detection when using pyrometers.
In WP7, VTT and FhG-ILT provided welded samples for tensile and fatigue tests at FhG-LBF, which were carried out both on overlapped and T-shaped specimens. Selected specimen were further analysed by microscopic investigation on microtome cuts (Figure 26). Tecnalia developed a machine-vision prototype with auto-calibration and post-process quality control, which works with an IPG fiber laser and and Arges scanning system. Tecnalia also developed the Global Supervision System (Figure 27), which was presented during the 2nd Review Meeting in M36. The system consists of three supervision steps: (1) pre-process supervision, (2) in-process supervision, and (3) post-process supervision. CRF developed an innovative signal analysis methodology for defect analysis based on the Orthogonal Hilbert-Huang Transform.
WP8: Validation of high productivity laser polymer welding processes with breakthrough reproducibility
The objectives of WP8 were to apply the new polymer welding strategies based on high brilliance laser sources on real applications (automotive, consumer goods industries, medical services), and to demonstrate the project outcome at shop floor level regarding productivity, quality and new product solutions.
In the automotive sector, CRF and INAUXA established that, compared to different other welding techniques, laser welding of polymers is competitive in terms of weld quality and cycle time. INAUXA selected a rear axle stabilizer link completely made of polymeric materials, and performed all steps from component design to process design and testing, validation and verification. CRF chose a third stop light and an instrument cluster window as final applications to be tested for laser welding.
In the medical services sector, Coloplast showed the possibility of welding a catheter housing with good results using a low cost laser welding system with an output power of 10 W. It was shown that the wavelength of 1940nm could also be interesting for laser welding of ostomy base plates.
Based on test case results in the white goods/consumer goods industry, Electrolux confirmed that a change of the traditional welding techniques towards laser welding could become realistic in a short period. Electrolux selected a washing machine handle as final test application, and experimented with different materials and colors. Test results show good mechanical resistance and aesthetical appearance. Figure 28 provides an overview of the different industrial sectors contributing to WP8, and their various test cases and samples.
The three prototype machines developed within WP5 (FhG-ILT: TWIST prototype machine, Leister: dynamic mask prototype machine, Cencorp: QSLW prototype machine) were used for welding tests for the different end user applications.
WP9: Dissemination, Training and Transfer of Knowledge
Over the course of the project, WP9 organised internal workshops and public events, developed a dissemination strategy for the project and generated dissemination material, managed external communication and oversaw exploitation and IPR plans and activities.
Two internal workshops for the project partners were organized in 2011 and 2012 to support exchange of knowledge and skills between the partners’ teams and to optimise integration effects and collaboration (see Figure 29).
To raise awareness for IPR aspects and exploitation of results, and to prepare the PUDF two exploitation seminars (ESS) were organized for the project partners in 2010 and 2012 (Figure 30, left).
In addition, two public workshops were organized to disseminate knowledge generated within the project and main project results to the larger public. They took place in the frame of the international conferences AKL (May 2012, Aachen, DE) and Laser World of Photonics (May 2013, Munich, DE) (Figure 30, right).
Dissemination of project results was furthermore achieved by different communication tools such as the project website www.polybright.eu flyers, roll-ups, newsletters (seven editions), press releases (four issues), university lectures, articles, scientific publications (15 papers: peer-reviewed journals, conference contributions) and booths at conferences and exhibitions (examples see Figure 31). The final project results were disseminated through a dedicated press release and a newsletter (both Sept. 2013) and a 20m2 booth at the fair K2013 (October 2013, Düsseldorf, DE) (Figure 32).
WP10: Project Management
WP10 was responsible for the overall strategic as well as financial and contractual management of the project. In the beginning of PolyBright, a dedicated project office was set up to establish the management infrastructure consisting of the project committees, boards, management procedures, a quality plan and a risk register, project management tools (financial and person month monitoring), and a secure collaborative internal website.
The project office organized, chaired and followed-up a total of four Steering Committee and five Management Committee meetings and the management board telephone conferences (23) over the course of the project (see Figure 33). Project quality control was ensured through continuous monitoring of the project progress against contractual commitments (deliverables and milestones). In addition, the project office maintained and updated all contractual documents, provided financial control for the project, and managed all financial reporting aspects and the distribution of EC payments. The project office acted as central contact point for all project partners.
In PolyBright, all project deliverables were monitored on a continuous basis and submitted according to schedule or with only minor delays. All contractual periodic reports were submitted to the European Commission on time on a regular basis (every 18 months), including scientific/technical reporting and financial statements. Regular internal review reports were also prepared on a regular basis (every 6 months). Rules and regulations as stipulated in the Grant Agreement and Consortium Agreement were implemented throughout the project.
Potential Impact:
Socio-economic impact
PolyBright had an overall positive impact on employment, workforce distribution and gender aspects in the participating organizations (universities, SMEs, industry). On the WP level, eight out of ten WPs were led by men. However, 16% of experienced researchers, 57% of PhD students, and 25% of other personnel working on the project were female. Over the course of the project, two additional researchers (male) were recruited specifically for PolyBright. Several project partners carried out specific gender equality actions, such as setting targets to achieve a gender balance, organising gender conferences and workshops, activities to improve the work-life balance, equal opportunity policies, father-daughter days, girls’ days, etc. PolyBright researchers were involved in outreach and education activities with school and university students through training activities (bachelor/master theses, laser processing courses), involvement of student workers, organization of open days, science nights, and girls’ days.
PolyBright did not directly work with or target policy makers. However, results originating from the project could be used by policy makers in the relevant fields, especially in international research and innovation and competition (e.g. competitive manufacturing processes).
Several publications were published in peer-reviewed journals; other publications were prepared for conference contributions (more details can be found in section 2.1.1). Additional dissemination activities are described in secion 1.4.3 and listed in section 2.1.2.
Wider societal implications of the project
As plastics play an important role in our everyday lives, new fast and reliable technologies for polymer manufacturing processes have a direct and wide impact on society as a whole. As new plastic materials with improved characteristics regarding optical properties, color, and additives content become available, laser welding of polymers can be introduced in more and more manufacturing processes and applied in an ever increasing number of industrial sectors. Laser welding of polymers is not only a fast and reliable process offering reduced cycle times, high throughput and automation options, but also provides high weld seam quality resulting in increased strength and durability of laser welded plastics parts. Products such as packaging, building materials, and high-tech products in the automotive, electronics, aerospace, white goods, medical and other sectors could benefit from the developments carried out in PolyBright, and from taking them to the next level of design, R&D and applicability.
Main dissemination activities
PolyBright results were published in peer reviewed journals and widely presented at national and
international conferences (details can be found in Section 2 of this report). Two public workshops held at the AKL conference (May 2012, Aachen, DE) and the Laser World of Photonics (May 2013, Munich, DE) and the presentation of key PolyBright results at the K fair in Düsseldorf (DE) in October 2013 constitute particular dissemination highlights. Two internal workshops were organized for all project partners and held in March 2011 (Torino, IT) and June 2013 (Helsingor, DK).
In total 43 Highlight documents summarizing key project results were published on the PolyBright website (www.polybright.eu) and seven newsletters were distributed and published in industrial magazines.
A PolyBright flyer containing information on the project and a brochure outlining the main results of PolyBright and telling the PolyBright story (product idea – material choice – adapted laser sources - machine concepts and realization – industrial applicatons) were distributed at the K fair in Düsseldorf. In addition, PolyBright and its activities were presented in a video on Horizon2020 by the European Commission.
Exploitation of results
Through the development and combination of new materials, adapted laser sources and new processes in the project, several laser welding prototype machines were built and their application shown in real test cases. PolyBright could successfully demonstrate the proof of concept for the developed technologies, which go beyond the prototype machines and include new materials and material combinations, special laser sources for polymer welding, new scanning devices, quality control methods, welding supervision systems, innovative clamping tools, and improved laser welding technologies and processes such as TWIST and dynamic mask welding.
Two Exploitation Strategy Seminars (ESS) were carried out over the course of the project to identify exploitable results, define background and foreground information as well as intellectual property rights (IPR), and develop possible business plans. Exploitation claims were identified and discussed widely in the consortium towards the end of the project. A detailed document listing all exploitation claims was generated and will be the reference guide for further discussions and developments.
The level of development of products and processes differs between exploitable results. Some partners are close to product development and prototypes already exist, others need to carry out further research and development before actual product development can start. With continued efforts it can be expected that the first technologies and products can enter the market in less than two years from the end of the project. Introducing laser welding technologies in industries which still use traditional/alternative welding techniques such as hot-plate welding, vibration welding or ultrasonic welding might take more time as new product designs adaped for laser welding, manufacturing chains, and safety regulations need to be put into place.
Different forms of exploitation are relevant for PolyBright key results. Depending on the exploitable result, licensing of single technologies and components (e.g. software developed in the project), use of new processes for the development of novel products and services, and manufacturing of new laser sources and laser welding machines combining different technologies and components are planned.
List of Websites:
www.polybright.eu Dr.-Ing. A. Olowinsky, Fraunhofer-ILT, Germany
Tel: +49 241 8906 491
Fax: +49 241 8906 121
E-mail: alexander.olowinsky@ilt.fraunhofer.de
Plastics play an important role in our lives, with a wide array of products such as everyday packaging, furniture and building materials, and high tech products in the automotive, electronics, aerospace, white goods, medical and other sectors. Today, advanced plastic polymers have already replaced other materials in the manufacturing, optical and electronics industry, and have driven drastic changes in the design and set up of almost all products in terms of weight reduction, cost saving and environmental impact. These are crucial factors for the success of both disposable and long lasting products in manufacturing and use.
The aim of PolyBright is to provide high speed and flexible laser manufacturing technologies required for the mass production of complex plastics parts, and to expand the limits of current plastic part assembly. New laser polymer joining processes for optimized thermal management in combination with wavelength adapted polymers and additives will provide higher quality, high processing speeds of up to 1 m/s and robust manufacturing processes at lower costs in order to meet future industries’ needs for speed, flexibility and quality of welding geometries. Key innovations of the PolyBright project are high brilliance mid-IR-wavelength fiber and diode lasers with powers up to 500 W, high speed scanning, and flexible beam manipulation systems such as dynamic masks and scanning heads with multi-kHz scanning speeds.
Project Context and Objectives:
Plastics play an increasingly important role in all aspects of everyday life, with a wide array of products such as packaging, furniture and building materials, and high tech products in the automotive, electronics, aerospace, white goods, medical and other industrial sectors. Polymeric materials have a vast potential for new exciting applications in many areas such as conduction and storage of electricity, heat and light; molecular based information storage and processing; molecular composites; unique separation membranes, new forms of food processing and packaging; medical devices; and housing and transportation. Today, advanced plastic polymers have already replaced other materials in the manufacturing, optical and electronics industry, and have driven drastic changes in the design and setup of almost all products in terms of weight reduction, cost saving and environmental impact. These are crucial factors for the success of both disposable and long lasting products for manufacturing and use. The large number of current and future applications of polymers has created the need to improve joining techniques for processing of polymeric materials. PolyBright addressed this need by advancing existing and developing new processes for laser welding of polymers.
The Idea | The initial objectives of PolyBright were to provide high speed and flexible laser manufacturing technologies required for the mass production of complex plastics parts, and to expand the possibilities of plastic part assembly. Furthermore, PolyBright objectives were to (1) improve existing welding techniques and overcome current limitations, (2) develop high brilliance laser sources in the higher NIR wavelength range which allow welding of polymeric materials without the need for IR absorbers or other additives, and (3) increase the process robustness and cycle times to ensure high manufacturing quality. New laser polymer joining processes for optimized thermal management in combination with wavelength adapted polymers and additives provide higher quality, high processing speeds of up to 1 m/s and robust manufacturing processes at lower costs in order to meet future industries’ needs for speed, flexibility and quality of welding geometries. Key innovations of the PolyBright project are high brilliance mid-IR-wavelength fiber and diode lasers with powers up to 500 W, high speed scanning, and flexible beam manipulation systems such as dynamic masks and scanning heads with multi-kHz scanning speeds.
Several European companies in the automotive, white goods and medical device industrial sectors, among other academic and SME partners, were involved in PolyBright. Their involvement was driven by the interest to implement laser welding techniques for relevant polymeric products in the production lines. These companies identified a range of products which highlight the advantages of this new joining technique.
Material Choice | Material requirements such as color (pigments, colorants) and the use of IR absorbers or various additives vary between industrial sectors. One of the objectives of PolyBright was to broaden the range of polymer materials and material combinations that are suitable for laser welding. The choice of material depends on the physical and chemical characteristics of the polymer and its intended use. Different material properties such as melting point, aliphatic/aromatic structure, and flexibility define the usability of the polymer for specific applications as well as its laser weldability. Adding fillers such as glass fibers or other inorganic fillers (e.g. talc) modifies the characteristics of the polymer. A high amount of glass fiber presents a challenge for laser welding due to the strong scattering effect on the laser beam. IR additives enhancing the absorption of laser energy in the polymer are for example Lumogen® IR and Pro-Jet™. Material families that were studied in PolyBright include polyolefins (PP, PE), styrenic copolymers (ABS, SAN), polyamides (PA6, PA66, PA11), and thermoplastic elastomers (PPA, PEBAX). Welding of white components, one of the biggest challenges in laser welding of polymers was achieved within PolyBright. Newly developed laser systems allow for a significant increase in the number of suitable color combinations.
Adapted Laser Sources | Various new laser systems were developed within PolyBright. For the development of a diode laser system, a laser module with 80W output power at a wavelength of 980nm and an M-shaped intensity distribution was assembled. Other systems are also available at higher wavelengths in the NIR (1550nm, 1650nm and 1940nm). Higher laser output powers were achieved through a combination of several laser diodes, the number of which is limited by the fiber core diameter and its numerical aperture. For laser welding of polymers withouth additives a specific high-brilliance fiber laser was developed within PolyBright. For this system, the fiber laser was doped with Erbium instead of Ytterbium which is the standard for industrial fiber lasers used for cutting and metal welding. The Erbium doped fiber results in a laser wavelength around 1.5µm which is suitable for welding or polymeric materials. The ELS-500 is a fiber laser system with a maximum output power of 500W emitting at 1567nm. Improved welding of polymers is possible by modifying the intensity distribution of diode lasers with specific optical elements. Suitable micro optics for use as beam shaping elements fot the high power diode lasers were designed and produced. A special bi-shape lens was developed for the transformation of the intensity profile into a so-called M-shape distribution. In addition, a concept for a system with selectable wavelengths between 1.5-2µm was developed.
Machine Concepts | New machinery was needed to combine the newly developed high brilliance laser sources, new optics and scanning technologies for laser welding of polymers. Three different prototypes were developed and set up in PolyBright: (1) Quasi-simultaneous laser welding machine prototype with additional xyz axes, (2) TWIST welding machine prototype with a laser source at 1.5µm, and (3) dynamic mask welding machine prototype in combination with a galvo scanner. (1) The Cencorp 1300 Offline QS prototype machine features the following properties and components: offline workstation, class 1 laser product, 1330x1440x1770mm (LxDxH), 1300kg, axis movement: x 744mm y 800mm z 200mm with Beckhoff motion control, OS: Windows 7, user interface: Cencorp custom solution, electrical power supply: 400V 3phase 50Hz 16A, pressured air supply for clamping unit, connection for fume extraction, ethernet connection. (2) The ILT TWIST welding prototype machine was set up with the following properties and components: Fiber Rhino 8.5 scanner (Arges), InScript scanner control software (Arges), focussing lens S4LFT 1330/008 (f=342mm, focus diameter 130µm, field 215x215mm), laser ELR120SMWC (IPG) (power 120W, wavelength 1567nm, beam diameter 5.5mm) special design clamping (ILT), manual loading, machine housing: special design (INTRO, ILT). (3) The Leister dynamic mask prototype machine includes the following properties and components: fiber laser 1070nm, variable beam shape for contour or highly variable simultaneous welding, laser power up to 100W (unpolarized), LCoS 600x800px, ethernet IP data interface, customer specific controller (ethercat), pilot laser <1mW, line voltage 200/230V, frequency 50/60Hz, 16A max. current consumption, compressed air connection 6x10^5Pa, air cooled (exhaust air max. 55°C), operable in 1540°C, 860x1240x1860mm (LxDxH), 400kg, laser class 1 (2M with aiming laser).
Industrial Applications | In virtually all areas of medicine, increasingly sophisticated devices are combined with increasingly advanced materials to solve the most challenging technical problems. From functionalities such as sterility and biocompatibility to active drug delivery and conductivity, polymers prove to be more versatile and complex than ever before. Advanced polymer research is leading to new and innovative medical devices. Areas with the highest potential appear to be tissue engineering and transplant medicine, devices delivering pharmaceuticals, and specialized polymer coatings. For this reason, Coloplast, an international company that develops, manufactures and markets medical devices and services related to ostomy, urology, continence and wound treatment now benefits from new welding techniques for advanced polymers. For Coloplast, laser welding is an attractive alternative to heat sealing, to date the most commonly used welding principle in the company. Laser welding is fast and enables designs that are not feasible with other joining techniques
Electrolux is a manufacturer of home and professional appliances and the second largest appliance manufacturer in the world. It sells more than 40 Mio products to customers in 150 countries annually. Electrolux products include refrigerators, dishwashers, washing machines, vacuum cleaners and cookers. Investigations in new materials, material combinations and possible joining techniques to enhance the asthetics of white goods products has led Electrolux to test laser welding as a new opportunity for improved design and quality of assemblies. The selected test case involves washing group tubs which are currently hotplate or vibration welded. This test case offers a complex shape geometry and complex material requirements. A suite of welding tests at 1567nm with different PCbased compounds (opaque white and grey) was realized to select the appropriate material. Optimal joint configuration, the most suitable laser source and welding process parameters were chosen according to design requirements.
The automotive sector is continuously changing due to challenging markets in a capitalintensive industry, declining consumer confidence and increased regulation. The combination of these new realities has resulted in the need to produce new materials and lightweight structural elements to satisfy the demand for cleaner and greener cars. Much of the recent research and innovation were aimed at replacing classical steel parts with lighter materials such as highperformance and ultraperformance plastics in virtually every major system in today's vehicles. The new materials increase mechanical performance and component efficiency to meet the challenges of rising costs, reduced weight and changing regulatory standards. This also involves the increase of automation in production lines. For this reason CRF and Industria INAUXA are interesed in the development of new polymer joining techniques such as laser welding. CRF carried out various tests for lighting systems and under hood components, e.g. a fuel filter housing. These tests showed that laser welding is competitive in terms of weld quality and cycle time, especially for the combination of dissimilar materials such as PP and PA66. For another industrial test case, CRF chose the dashboard cluster of the Alfa Romeo Giulietta. The materials that were used include PMMA and black ABS for the instrument cover and the housing. The components are currently designed for ultrasonic welding. INAUXA performed several welding tests and decided to evaluate the advantages of the laser welding technique for stabilizer links connecting opposite (left/right) wheels together through short lever arms linked by a torsion spring. They increase the suspension's roll stiffness, i.e. its resistance to roll in turns, independent of its spring rate in the vertical direction. There are different models of stabilizer links, but all of them are made of PA66 with and without fiber glass. The percentage of fibers in the parts depends on the end user. INAUXA modified the material combination to achieve laser welding feasibility and was successful in fixing the PA66 ball race (white) to the PA66 housing (black) by using a diode laser.
Over the entire duration of the PolyBright project, the consortium worked together in a highly collaborative and well-organized fashion. The project was focused on the development of novel polymeric materials, new laser sources and optics, and innovative laser welding machines, with a special emphasis on collaboration between those partners validating the newly developed technologies through the industrial applications in the automotive, white goods and medical sectors. All test cases have shown that laser welding of polymers is feasible and comparable with established joining techniques in terms of productivity, quality, cycle time and process robustness. Specific highlights for each technical work package and the main achievements are summarized in section 1.3.
Project Results:
Figure 3 shows an overview of the interactions and dependencies among the different work packages within PolyBright. The project was well set up and organized to achieve all targeted objectives. The following pages summarize the main project results and the gain in knowledge and technological progress achieved throughout the project.
WP1: Specifications and user requirements
In WP1 all objectives were achieved. The products, materials, processes, additives to be manufactured in the PolyBright project were specified and defined.
The products and basic test samples demonstrated the capabilities of high power high brilliance lasers with new wavelengths between 1500 and 1900 nm which were adapted to the absorption properties of polymers. LIMO developed novel high brightness diode lasers at 1.7 – 1.9 µm wavelength plus novel beam shaping devices in order to improve the business case for laser processing of thermoplastics. Additives and colorants were added according of the needs of the end users. These additives were well suited for transforming a non-absorbing resin into an absorbing one and achieve aesthetical end user requirements.
ELUX as one of the project end users analysed, selected and defined some possible test cases belonging to the sector (as washing group tubs, handles, control panels) for the application and validation of the Polybright technology. A dedicated document was written for illustrating and explaining the user requirements for these applications. Moreover, a specific matrix was filled-in for describing and applying within the project the testing procedures for welding specimens.
Different welding processes developed in Polybright were validated, and different kinds of tests were carried out by the PolyBright partners in the different project phases to ensure the best welding quality. All milestones and deliverables were submitted.
WP2: Development of high brilliance laser sources
One of the main highlights of WP2 was the development and production of three high brilliance fiber laser sources according to the PolyBright Description of Work:
- ELR-120-Polybright, 120 W Erbium doped fiber laser with 1567 nm wavelength and single mode beam quality
- TLR-120-Polybright, 120 W Thulium doped fiber laser with 1940 nm wavelength and single mode beam quality
- ELS-500-Polybright, 500 W Erbium doped fiber laser with 1567 nm wavelength, 200 µm feeding fiber core diameter and multi mode beam quality providing beam with top hat distribution
Optical and electrical properties were characterized and input for beam shaping optics was generated.
Refractive micro optics for laser beam collimation and beam shaping were designed and fabricated.
Besides high brilliance fiber lasers, WP2 focused on developing and setting up fiber-coupled diode laser systems with new wavelengths in the far-infrared spectral range between 1500 and 1900 nm. All these diode lasers are coupled into a 400 µm diameter fibre core (numerical aperture NA=0.22) and deliver output power up to 80 W. In addition, a laser module with 80W output power at a wavelength of 980nm and an M-shaped intensity distribution was assembled.
WP3: High speed scanning and product specific beam shaping
In laser polymer welding, a rapid and robust welding process is essential. This need was faced in WP3. Fused-silica mirrors in two different scanning systems were replaced by silicon carbide mirrors resulting in a remarkable speed improvement of laser beam deflection. One of these systems is a 2D scanner featuring an f-theta lens whereas the other one is based on a f-theta-less 3D approach featuring a focus translation stage at the scanner’s input aperture. In addition to the replacement of the mirrors, the optical elements of both systems were adapted to wavelengths in the range between 1.5 up to 2 m.
Refractive and diffractive beam shaping techniques were developed and applied in order to achieve a wider process window and a more stable welding process. The improvement was based on the generation of a so-called “M-shaped” intensity spot profile resulting in a homogeneous temperature distribution across the seam during welding. Furthermore, the diffractive beam shaping technique was extended to constructing, setting up and testing a highly-variable beam shaping tool by implementating a phase modulator array, i.e.a liquid-crystal-on-silicon (LCoS) display, operated in reflection With this prototype machine, which was exhibitied during the K2013 fair in Düsseldorf, simultaneous laser welding can be extended considerably. Current limitations due to a high effort for changing the weld contour can be completely avoided by this technique. Key elements are the LCoS reflection device as well as polarized 1060 nm fiber laser radiation with 100 Watt maximum output power.
By shaping a high-brilliance fiber laser beam to a very well collimated laser line, a very precise mask welding system was developed allowing weld resolution in the range of 50 m which is a substantial progress compared to generating line beams from low-brightness diode laser beam sources Herein, a copper mask especially designed for high laser power density was applied.
WP4: Flexible, robust and fast-adapting laser beam welding
WP4 deals with the laser welding process itself with special respect to the welding method, heat transfer considerations and process-related geometrical aspects. A computer model based on heat conduction as well as polymer laser beam scattering yields temperature distributions which are in good accordance with microtome slice cuts of laser welded flat samples, particularly for applying the TWIST welding method to homogenise the heat affected zone.
It has been proven that TWIST welding enlarges the process window and increases polymer laser welding applicability using fiber laser in addition to diode laser radiation (see Figure 8, right).
The remote welding opportunities are increased due to the use of high-brightness fiber laser radiation and scanner lenses with long focal lengths. With two scanners, a so-called dual-head configuration was set up and was able to weld 400x400mm polymer plates. Furthermore, a highly variable clamping concept, based on a pressure chamber together with an elastic transparent foil was constructed, set up and tested as a prototype.
For high speed quasi-simultaneous laser welding around 10m/s, software was developed to smooth the energy input along the weld contour (Figure 9).
This is difficult to achieve at high speed in sharp corners, but was solved by developing an Intelligent Power Control (IPC) software to adapt the laser power cycle by cycle.
For one-shot welding, diffractive optical elements (DOEs) were manufactured and irradiated by pulsed laser radiation to generate shaped (square) contours. Another application for these DOEs is to transform a Gaussian laser beam intensity distribution into tophat shape or M-shape which was shown to improve energy input homogenisation (see Figure 10).
Besides 1µm wavelength which was used for regular polymer overlap welding, fiber lasers with 1.94 µm were developed to ensure polymer butt welding capability. This configuration needs optical penetration depths of both partners in the mm range.
Mask welding with line beam-shaped fiber laser radiation is advantageous to using line beam-shaped diode laser radiation, because a high spatial resolution can be achieved even at large distances between mask and work piece due to fiber lasers’ high brightness character (see Figure 13).
An important WP4 Highlight was the construction, key element selection and setup of a dynamic mask machine. This prototype allows highly flexible beam shaping for contour welding as well as highly flexible contour shaping for one-shot simultaneous welding. Key element is a Liquid Crystal on Silicon (LCoS) reflective mirror (details see Figure 14).
WP5: New machines for cost effective manufacturing with increased reliability
The main highlight of WP5 was the build-up of three laser system prototype machines for the welding of polymer materials:
- FhG-ILT’s TWIST welding machine prototype at 1.5μm
- Leister’s dynamic mask prototype machine in combination with a galvo scanner
- Cencorp’s quasi-simultaneous welding machine prototype with additional xyz axes
These prototype machines were developed on the basis of high-brilliance beam sources and welding processes developed within the project. Processes included for example optimized beam intensity profiles and optimized beam oscillation patterns for polymer materials. Prototype machines and welding processes were tested with real polymer products from the automotive, medical and white good sectors. In the white goods sector, the TWIST prototype machine was tested on washing machine door handle parts. In the automotive sector, the dynamic mask and QSLW machines were used for welding stabiliser links, meter frames and windows.
The prototype machine using dynamic mask welding combines a scanning system with the dynamic mask technology. Hardware and software were adapted to the workstation with the LCoS technology at Leister. The machine was presented during the K-Fair in Düsseldorf in October 2013.
To complement the activities of WP5, a flexible clamping device, easily adapted to different component geometries to be welded and an appropriate fixture to perform the welding test campaign on the selected test case (washing machine handle) was realised.
Moreover an evaluation of the final prototype system functionalities was carried out in relation to the white goods sector applications. In particular, the assessment was focused on estimating hypothetical real working environment conditions to validate the welding process cycle time and the capacity of the system to deal with mass production volumes as required by the sector/end user.
In total six experimental system setups were built out of which the three above mentioned experimental setups (TWIST welding, dynamic mask welding, QSLW) were selected for the built up of the three laser machine prototypes. The six experimental setups were:
- High resolution mask welding
- Dynamic mask welding
- DOE for beam shaping in scanning system
- Remote welding
- Quasi-simultaneous welding
- TWIST
WP6: Advanced materials, additives and product design for high speed welding
WP6 has given a very good experimental background for understanding the effect of absorbers, colours and laser wavelengths on partners’ welding ability. This background resulted in guidelines for users of the laser welding process. WP6 demonstrated the interest of using higher wavelength laser sources for laser welding of challenging material combinations, for instance transparent on transparent (low laser absorption) and white on white (high laser reflection). In WP6, new IR absorbers were tested and one in particular enabled significant cost savings for project partner Colopast. WP6 has also given interesting insights into computer simulation of mechanical resistance of welded samples, an important task for quality control and assurance. One of these simulation tools, based on ARMINES ARCAN mechanical test, can be used to design complex welding structures as the results do not depend on the system geometry. Results from WP6 have formed the basis for the work in WP8 and the demonstrators.
WP6 partner Treffert produced compounds of material, either unfilled or with additivies such as carbon black (CB) or different colorants. Partners Arkema and FhG-LBF worked on the selection process of the polymer materials and IR absorbers to be tested considering the material requirements of all partners. In addition, several injection campaigns were carried out to produce test samples for mechanical characterization (overlapped joint specimen, T-shape specimen, example see Figure 18).
WP6 carried out various measurements for each tested polymer material, such as specific heat tests, polymer density tests as a function of temperature, fatigue tests (Figure 19) and static tension tests. Optical properties of the materials were also measured (Figure 20). Static tension tests were carried out for overlapped joint and T-shape specimen, and fatigue tests were performed on notched and unnotched samples. Finite element calculations were performed to determine the highly stressed material volume of the laser welded samples. In addition, overmolding experiments were performed (by co-injection molding) to evaluate the weldability of all material combinations (see Figure 21).
The end users in the project, Electrolux and Coloplast, provided context information about the required polymeric materials for their use, and contributed to the definition of suitable and promising solutions to be applied and tested for laser welding. Welding trials with different absorbing and transparent part combinations were carried out at Coloplast (Figure 22).
WP7: Quality assurance and process control for zero failure manufacturing
The objective of WP7 was to develop quality assuarance strategies. This was accomplished using cameras, pyrometers and high speed thermal imaging. Mechanical testing of welded samples was also a part of quality assurance. Pyrometers were used as reference since they are already used in the industry. High speed thermal imaging was seen as a viable option for R&D activities but their speed and sensivity are not high enough for online control and thus for industrial application. Camera positioning is useful in many cases if part positioning needs to be corrected or tracked. The Global Supervision System (GSS) developed within the project showed good potential of camera-based positioning system capabilities. Mechanical testing of welded samples gave a good insight into weld properties. Signal analysis and the developed methods were seen as a very powerful method for defect detection when using pyrometers.
In WP7, VTT and FhG-ILT provided welded samples for tensile and fatigue tests at FhG-LBF, which were carried out both on overlapped and T-shaped specimens. Selected specimen were further analysed by microscopic investigation on microtome cuts (Figure 26). Tecnalia developed a machine-vision prototype with auto-calibration and post-process quality control, which works with an IPG fiber laser and and Arges scanning system. Tecnalia also developed the Global Supervision System (Figure 27), which was presented during the 2nd Review Meeting in M36. The system consists of three supervision steps: (1) pre-process supervision, (2) in-process supervision, and (3) post-process supervision. CRF developed an innovative signal analysis methodology for defect analysis based on the Orthogonal Hilbert-Huang Transform.
WP8: Validation of high productivity laser polymer welding processes with breakthrough reproducibility
The objectives of WP8 were to apply the new polymer welding strategies based on high brilliance laser sources on real applications (automotive, consumer goods industries, medical services), and to demonstrate the project outcome at shop floor level regarding productivity, quality and new product solutions.
In the automotive sector, CRF and INAUXA established that, compared to different other welding techniques, laser welding of polymers is competitive in terms of weld quality and cycle time. INAUXA selected a rear axle stabilizer link completely made of polymeric materials, and performed all steps from component design to process design and testing, validation and verification. CRF chose a third stop light and an instrument cluster window as final applications to be tested for laser welding.
In the medical services sector, Coloplast showed the possibility of welding a catheter housing with good results using a low cost laser welding system with an output power of 10 W. It was shown that the wavelength of 1940nm could also be interesting for laser welding of ostomy base plates.
Based on test case results in the white goods/consumer goods industry, Electrolux confirmed that a change of the traditional welding techniques towards laser welding could become realistic in a short period. Electrolux selected a washing machine handle as final test application, and experimented with different materials and colors. Test results show good mechanical resistance and aesthetical appearance. Figure 28 provides an overview of the different industrial sectors contributing to WP8, and their various test cases and samples.
The three prototype machines developed within WP5 (FhG-ILT: TWIST prototype machine, Leister: dynamic mask prototype machine, Cencorp: QSLW prototype machine) were used for welding tests for the different end user applications.
WP9: Dissemination, Training and Transfer of Knowledge
Over the course of the project, WP9 organised internal workshops and public events, developed a dissemination strategy for the project and generated dissemination material, managed external communication and oversaw exploitation and IPR plans and activities.
Two internal workshops for the project partners were organized in 2011 and 2012 to support exchange of knowledge and skills between the partners’ teams and to optimise integration effects and collaboration (see Figure 29).
To raise awareness for IPR aspects and exploitation of results, and to prepare the PUDF two exploitation seminars (ESS) were organized for the project partners in 2010 and 2012 (Figure 30, left).
In addition, two public workshops were organized to disseminate knowledge generated within the project and main project results to the larger public. They took place in the frame of the international conferences AKL (May 2012, Aachen, DE) and Laser World of Photonics (May 2013, Munich, DE) (Figure 30, right).
Dissemination of project results was furthermore achieved by different communication tools such as the project website www.polybright.eu flyers, roll-ups, newsletters (seven editions), press releases (four issues), university lectures, articles, scientific publications (15 papers: peer-reviewed journals, conference contributions) and booths at conferences and exhibitions (examples see Figure 31). The final project results were disseminated through a dedicated press release and a newsletter (both Sept. 2013) and a 20m2 booth at the fair K2013 (October 2013, Düsseldorf, DE) (Figure 32).
WP10: Project Management
WP10 was responsible for the overall strategic as well as financial and contractual management of the project. In the beginning of PolyBright, a dedicated project office was set up to establish the management infrastructure consisting of the project committees, boards, management procedures, a quality plan and a risk register, project management tools (financial and person month monitoring), and a secure collaborative internal website.
The project office organized, chaired and followed-up a total of four Steering Committee and five Management Committee meetings and the management board telephone conferences (23) over the course of the project (see Figure 33). Project quality control was ensured through continuous monitoring of the project progress against contractual commitments (deliverables and milestones). In addition, the project office maintained and updated all contractual documents, provided financial control for the project, and managed all financial reporting aspects and the distribution of EC payments. The project office acted as central contact point for all project partners.
In PolyBright, all project deliverables were monitored on a continuous basis and submitted according to schedule or with only minor delays. All contractual periodic reports were submitted to the European Commission on time on a regular basis (every 18 months), including scientific/technical reporting and financial statements. Regular internal review reports were also prepared on a regular basis (every 6 months). Rules and regulations as stipulated in the Grant Agreement and Consortium Agreement were implemented throughout the project.
Potential Impact:
Socio-economic impact
PolyBright had an overall positive impact on employment, workforce distribution and gender aspects in the participating organizations (universities, SMEs, industry). On the WP level, eight out of ten WPs were led by men. However, 16% of experienced researchers, 57% of PhD students, and 25% of other personnel working on the project were female. Over the course of the project, two additional researchers (male) were recruited specifically for PolyBright. Several project partners carried out specific gender equality actions, such as setting targets to achieve a gender balance, organising gender conferences and workshops, activities to improve the work-life balance, equal opportunity policies, father-daughter days, girls’ days, etc. PolyBright researchers were involved in outreach and education activities with school and university students through training activities (bachelor/master theses, laser processing courses), involvement of student workers, organization of open days, science nights, and girls’ days.
PolyBright did not directly work with or target policy makers. However, results originating from the project could be used by policy makers in the relevant fields, especially in international research and innovation and competition (e.g. competitive manufacturing processes).
Several publications were published in peer-reviewed journals; other publications were prepared for conference contributions (more details can be found in section 2.1.1). Additional dissemination activities are described in secion 1.4.3 and listed in section 2.1.2.
Wider societal implications of the project
As plastics play an important role in our everyday lives, new fast and reliable technologies for polymer manufacturing processes have a direct and wide impact on society as a whole. As new plastic materials with improved characteristics regarding optical properties, color, and additives content become available, laser welding of polymers can be introduced in more and more manufacturing processes and applied in an ever increasing number of industrial sectors. Laser welding of polymers is not only a fast and reliable process offering reduced cycle times, high throughput and automation options, but also provides high weld seam quality resulting in increased strength and durability of laser welded plastics parts. Products such as packaging, building materials, and high-tech products in the automotive, electronics, aerospace, white goods, medical and other sectors could benefit from the developments carried out in PolyBright, and from taking them to the next level of design, R&D and applicability.
Main dissemination activities
PolyBright results were published in peer reviewed journals and widely presented at national and
international conferences (details can be found in Section 2 of this report). Two public workshops held at the AKL conference (May 2012, Aachen, DE) and the Laser World of Photonics (May 2013, Munich, DE) and the presentation of key PolyBright results at the K fair in Düsseldorf (DE) in October 2013 constitute particular dissemination highlights. Two internal workshops were organized for all project partners and held in March 2011 (Torino, IT) and June 2013 (Helsingor, DK).
In total 43 Highlight documents summarizing key project results were published on the PolyBright website (www.polybright.eu) and seven newsletters were distributed and published in industrial magazines.
A PolyBright flyer containing information on the project and a brochure outlining the main results of PolyBright and telling the PolyBright story (product idea – material choice – adapted laser sources - machine concepts and realization – industrial applicatons) were distributed at the K fair in Düsseldorf. In addition, PolyBright and its activities were presented in a video on Horizon2020 by the European Commission.
Exploitation of results
Through the development and combination of new materials, adapted laser sources and new processes in the project, several laser welding prototype machines were built and their application shown in real test cases. PolyBright could successfully demonstrate the proof of concept for the developed technologies, which go beyond the prototype machines and include new materials and material combinations, special laser sources for polymer welding, new scanning devices, quality control methods, welding supervision systems, innovative clamping tools, and improved laser welding technologies and processes such as TWIST and dynamic mask welding.
Two Exploitation Strategy Seminars (ESS) were carried out over the course of the project to identify exploitable results, define background and foreground information as well as intellectual property rights (IPR), and develop possible business plans. Exploitation claims were identified and discussed widely in the consortium towards the end of the project. A detailed document listing all exploitation claims was generated and will be the reference guide for further discussions and developments.
The level of development of products and processes differs between exploitable results. Some partners are close to product development and prototypes already exist, others need to carry out further research and development before actual product development can start. With continued efforts it can be expected that the first technologies and products can enter the market in less than two years from the end of the project. Introducing laser welding technologies in industries which still use traditional/alternative welding techniques such as hot-plate welding, vibration welding or ultrasonic welding might take more time as new product designs adaped for laser welding, manufacturing chains, and safety regulations need to be put into place.
Different forms of exploitation are relevant for PolyBright key results. Depending on the exploitable result, licensing of single technologies and components (e.g. software developed in the project), use of new processes for the development of novel products and services, and manufacturing of new laser sources and laser welding machines combining different technologies and components are planned.
List of Websites:
www.polybright.eu Dr.-Ing. A. Olowinsky, Fraunhofer-ILT, Germany
Tel: +49 241 8906 491
Fax: +49 241 8906 121
E-mail: alexander.olowinsky@ilt.fraunhofer.de