Research by Fraunhofer ILT looked at new lightweight construction solutions, joining technology and end face seams for martensitic chromium steels.
Martensitic chromium steels are one of the steel grades with a future: they are steels that are ideal for automotive applications since they are both lightweight and corrosion resistant. These materials are particularly in demand for the design of collision-safe battery boxes for electric cars. For this reason, the Fraunhofer Institute for Laser Technology (ILT) uses these sophisticated components as demonstration components for laser welding and heat treatment.
As part of the AiF research project FAAM, supported by Forschungsvereinigung Stahlanwendungen e.V. (FOSTA), experts from industry and research took a close look at the current status of those grades. The final online conference in summer 2020 focused on new lightweight construction solutions, joining technology and end face seams, among other things, for martensitic chromium steels.
In detail, Fraunhofer ILT investigated how suitable it is to weld a press-hardened chromium steel with martensitic microstructure X46Cr13 (1.4034) in similar and dissimilar joints for assembly applications; this steel is considered difficult to weld due to its high carbon content. The dissimilar joints were combinations with work-hardened high-manganese steel (1.4678), press-hardened manganese-boron steel (1.5528), high-strength dual-phase steel (1.0944) and cold-rolled fine-grained structural steel (1.0984).
Martin Dahmen of the Macro Joining and Cutting Group at Fraunhofer ILT explains, “The main focus was on the mixing of the different materials, on the metallurgy and the resulting property profiles.”
The joining quality can be improved by heat treatment. For this purpose, linear seams of a 1.4034 joint of the same type were heat-treated in the lap joint from 300 to 700 deg C outside the process (ex-situ); the seams had to prove their quality in the subsequent shear tensile test.
“At 400 to 500 deg C, the highest strengths and lowest hardnesses were obtained,” explains Dahmen. “Remarkable is the high proportion of ductile failure on the fracture surface already at 400 deg C.”
The researchers aimed at reaching short holding times in order to use laser radiation for heat treatment.
AMADA WELD TECH has launched its Jupiter series of modular systems for precision joining, available for laser welding, laser marking, resistance welding, micro arc welding, and hot bar bonding applications. Jupiter modular systems can be equipped with all joining process modules available from AMADA WELD TECH to provide solutions to customers.
With the Jupiter series, customers purchase an automation platform from a global joining equipment leader and receive intensive process development support in AMADA WELD TECH application development centers. Joint early stage process development in AMADA WELD TECH labs ensures that customers receive the ideal system solution for years of high-quality production. Any welding, soldering, bonding, brazing, laser micromachining, and laser marking application can be handled by equipment in the Jupiter series.
The Jupiter modular system platform is a flexible system that comes in four sizes, so it is adaptable to specific production requirements. The stable platform enables connections of very high quality and accuracy. The modular design is configurable to fit all process components and modules. The Jupiter models feature an ergonomic system design with high quality components, designed for 24/7 continuous production. All models are equipped with a human-machine interface (HMI) with touchscreen for easy programming and standard safety features.
Control systems, based upon a programmable logic controller (PLC) or industrial PC, collect all available process parameters and process data into one control system. The data can be stored in local and remote storage areas, all engineered to seamlessly integrate with an Industry 4.0 factory concept.
Optional features for the Jupiter systems include a combustion suppression unit (CSU) for battery pack welding; a transport system with two individual belts that can be configured for a wide range of product carriers, including transfer systems; an automatic cleaning station for electrodes and thermodes; a “Not OK” bin to separate products outside the control limits from those within control limits; and a range of water cooling options. Also available are upgraded data collection and traceability functionalities, including a barcode reader or a label printer; and interfaces for a variety of robotic systems.
By equipping welding robots with “vision” and artificial sensory perception, part and positional variations can be adjusted in real-time, making it possible to account for variations such as inconsistencies in tool fixturing, deviations in part fit-up, weld seam geometry, and weld seam direction, during welding. Article by Wee How Tan, Servo-Robot.
Unlike skilled human welders, welding robots don’t have any natural intelligence nor cognitive senses. A robot will only perform what it has been programmed to do and move to where the program tells it to go. How good a robot can weld is therefore largely dependent on the skill and experience of the operator who programmed it. Without this imparted intelligence, the robot will weld “blind”.
To put the robot on the required trajectory at all times, the operator needs to constantly make changes to adapt the robot program to account for not only whatever is in front and around the robot arm, but also the variations in the part that the robot is welding.
Nowadays, a custom fab shop may fabricate a part to fulfil a large-volume order and then a few months later, it may receive another order for the same part again. For cashflow reasons, most customers want to avoid holding a large inventory of the same parts so they only order what they need at a particular time and then reorder when they need the parts again.
Owing to variations in forming and upstream cutting processes and other factors, different batches of the same part may not be exactly the same especially if they are supplied months apart. This means that the robot program made for a previous batch of parts will have to be adjusted for the new batch to account for variations between the batches.
This would not pose a problem if it is always the same part. However, fab shops invest in robotic welding systems to handle many different parts in variable quantities. Apart from having to build the tool fixtures to hold each new part, fab shops also have to manually program the robot and then adjust the program to account for the variations in each different batch of the same parts.
Trumpf has released its first automated arc welding system. The TruArc Weld 1000 comes with a collaborative robot known as a “cobot”. After the operator has manually guided it over a component, the cobot then automatically carries out the weld. It is significantly more efficient than would be possible manually. With the new system, Trumpf is responding to the increasing lack of skilled workers and helps fabricators get started with automated welding. CE-compliant and approved by TÜV Austria, the TruArc Weld 1000 meets the very highest safety standards.
Unlike conventional industrial robots, operators can interact with the cobot, guiding it over the part by hand. A built-in sensor ensures it responds smoothly. Trumpf has equipped the cobot with an operating unit. This lets users store the weld path’s start and end points as well as intermediate waypoints in order to create the program. Furthermore, the cobot control system includes templates for welding programs and parameters that cover scenarios such as different sheet thicknesses. Combined with the operating unit on the welding torch, this greatly simplifies the task of programming the robot. This enables users to program and weld with the TruArc Weld 1000 within minutes. Next to no previous experience is needed handling the system.
The TruArc Weld 1000 offers an automated alternative for many parts that users would normally weld by hand. Thanks to the rapid programming, fabricators have an affordable means of tackling short production runs and one-off pieces, even if the parts only require a short weld seam. The TruArc Weld 1000 produces reproducibly straight and even seams, prevents spatter and offers very high machining quality.
Inside the TruArc Weld 1000 is a partition that can be raised and lowered. This allows users to divide up the working area and choose between welding one large part (single-station operation) or several smaller ones (two-station operation). In single-station operation, the robot can weld parts measuring up to 2000 x 600 x 600 millimeters. Other ratios of width to length are also possible depending on part dimensions. In two-station operation, the TruArc Weld 1000 can process smaller parts measuring up to 600 x 600 x 600 millimeters. To ensure it can easily reach both stations, the robot travels between two positions along a linear axis. While it is busy welding on one side, the operator can use the time to set up a part on the other side. The robot program can be transferred automatically from one station to the other.
Ready to go with no training required
Customers can carry out commissioning of the CE-compliant TruArc Weld 1000 themselves within a few hours using the dedicated video tutorials. From the wire coil to the welding parameters, the system comes with everything you need to get started with the welding process. No classroom training is required for machine operators. The video tutorials contain all the information required to quickly learn how to operate and program the machine.
AMADA WELD TECH, formerly AMADA MIYACHI EUROPE has announced its new company name, effective April 1, 2020. This name change will allow the company to present themselves as an AMADA group company with the highest experience in welding and associated precision technologies.
The new name will soon appear on all mailings, invoices, packaging, and other promotional materials.
The company itself remains the same, simply under a new name. The same commitment to customers, products, quality of service, and employees will continue unchanged. The extensive range of equipment and systems in Laser Welding, Laser Marking, Laser Cutting, Resistance Welding, Hermetic Sealing and Hot Bar Reflow Soldering & Bonding will remain at the highest quality that our customers have come to know and expect.
AMADA WELD TECH requests that customers update records accordingly and address all future business correspondence to the new name, AMADA WELD TECH.
Amada Miyachi Europe announces the availability of the new MM-L300A Laser Weld Monitor. The compact MM-L300A is designed to detect welding defects and errors such as gaps between parts, missing parts, weld depth over-penetration, incorrect focus point and cover gas absence. It is providing operators feedback on the resultant laser weld quality. The compact, lightweight unit supports laser welding technologies for spot or seam welds.
This high-accuracy monitor is ideal for both process development and quality control for laser welding applications. The MM-L300A indicates weld quality by detecting and recording a thermal signal from the area of laser interaction and converting this into a graphical waveform. Part of the intelligence of this third-generation process monitor is that not only absolute max/min limits can be set but also value envelopes can be drawn around the waveform. Once the limits are determined, the unit compares a new weld waveform in real time to identify a good or bad weld. Providing high temporal resolution – down to 1 microsecond – the MM-L300A, with the SU-N300A dedicated thermal sensor, enables precision monitoring of both continuous wave and pulsed laser processes.
The MM-L300A features easy-to-use software for simple sensor configuration, waveform envelope limit set-up, and real-time or saved waveform analysis on Windows PCs. Additionally, machine-selectable setup schedules enable the unit to monitor different welding conditions. The compact, 3 kg (7 lb) unit reduces set-up space when integrated into a production line or used in a laboratory environment. The sensor can be mounted either on the optical axis of the laser beam trajectory or in an off-axis position.
SmartWeld+ is an add-on for Coherent StarFiber laser welding products that delivers dramatically improved results, particularly when welding dissimilar or otherwise challenging materials, such as aluminium and copper.
Specifically, for dissimilar materials, SmartWeld+ improves blending of the melt pool for a better metallurgical bond and more consistent results. When welding highly reflective or volatile materials, SmartWeld+ increases process stability and reduces spatter, porosity and cracking, because it produces lower viscosity and reduced surface tension in the melt pool.
The ability of SmartWeld+ to better control energy input into the material also decreases the heat affected zone (HAZ). It is particularly suitable for welding thin, dissimilar and/or temperature-sensitive materials. Additionally, SmartWeld+ simplifies welding workpieces with poor fit-up tolerances since it allows the width and depth of the weld seam to be controlled independently of the focused laser spot size. Together, these features make SmartWeld+ a candidate for precision welding in medical device manufacturing, microelectronics fabrication, e-mobility production and even watchmaking.
SmartWeld+ comprises a processing head, containing fixed beam delivery optics and a galvanometer scanning module, together with sophisticated software for producing a variety of pre-programmed patterns, which move well beyond beam wobble to encompass spirals, ellipses and other complex shapes. Furthermore, the pattern size and orientation can be controlled to follow part contours and achieve constant weld quality and seam dimensions.
SmartWeld+ integrates smoothly with Coherent StarFiber products and significantly extends their capabilities. The combination of fast scanning (up to 4kHz) and high-precision motion makes SmartWeld+ particularly suitable for on-the-fly adaptation.
BrightLine Weld enables low spatter laser welding at feed rates, only achievable today with CO2 lasers. Partial penetration welds for powertrain applications or full penetration welds for pipes and tubes applications – BrightLine Weld has the potential to revolutionise laser welding. Article by TRUMPF.
The technology allows for vastly improved productivity and energy efficiency. High quality weld seams result in high mechanical strengths of components produced. Minimised spatter behaviour reduces contamination of workpieces, clamping devices and optics, as well. That results in reduced machine downtime, less rework of parts, long cover slide lifetime and hence significantly reduced costs.
Introduction And Motivation
Reduction of cycle time and improved productivity play an ever increasing role in current industrial manufacturing. Especially within the automotive industry, where the total length of laser welded seams can add up to 60 metres per car, it is important to minimise processing time by means of high welding speeds. Perfect basis are fibre guided solid state lasers, eg, disk lasers with high beam quality at laser powers in the multi-kW range. Yet, the use of modern solid state lasers comes not for free; obstacles need to be overcome, ie, heavy spatters and contamination of workpieces and clamping devices.
Compared to conventional welding, laser welding allows for heat conduction welding and deep penetration welding, as well. Thin and deep weld seams can be produced contact free and at high feed rates. A small heat affected zone (HAZ) minimises thermal distortion of parts. Welding depth can be as 10 times larger than the welding width and can reach up to 25 mm.
Yet, feed rates are limited for laser welding. One important factor is spatter behaviour and resulting mass loss of the weld seam. In general, both of these aspects increase with feed rate and laser power used. Solid state laser welding of mild steel typically results in increased mass loss starting from a feed rate of 5 m/min.
Limitations Of Welding With Solid State Lasers
Increased spatter behaviour at higher feed rates:
Risk of mass loss at high feed rates leads to side kerfs at the seam front side which results in low mechanical strength and quality of the weld seam.
Clamping devices are being contaminated and need to be cleaned. That leads to unproductive machine down-times.
Cover slide glasses need to be re-placed often which results in increased costs.
So far, acceptable spatter behaviour could only be achieved at feed rates of up to 5 m/min hence resulting in low productivity.
That is a contradiction to the current demand for reduced cycle time within industrial production facilities. With the new welding technology BrightLine Weld, TRUMPF offers for the first time a solution meeting these requirements.
BrightLine Weld: Low Spatter Welding
BrightLine Weld is a new technology which allows for an almost spatter free welding process during deep penetration welding, even at high feed rates.
Figure 1: Welding depth depending on welding speed. The state of the art is compared with the BrightLine Weld technology.
Slim and deep weld seams produced with BrightLine Weld are of high quality. The low spatter formation results in the process regime extending to significantly higher feed rates. Figure 3 illustrates the welding depth depending on the feed rate at a laser power of 5 kW in mild steel both for the state of the art laser welding and for BrightLine Weld. The colour of the data points in the diagram is an indicator of the quality of the weld seam achieved:
Green: weld seam of high quality, which meets current requirements.
Yellow: weld seam of medium quality, which does not meet all requirements, but is acceptable for various applications.
Red: weld seam of poor quality, which is not acceptable anymore.
Violet: from this welding speed humping occurs. The resulting weld seam quality is insufficient.
The data points of the BrightLine Weld curve are green up to a speed of 20 m/min. Up to this range, the weld seam is of high quality. In the state of the art, the data points are yellow at a welding speed of 5 m/min. For even higher welding speeds, they are red or violet. Thus the quality of the weld seam at 5 m/min is only medium and poor or insufficient at higher speeds. This means that with BrightLine Weld, the maximum feed rate in mild steel could be increased by approximately +300 percent up to 20 m/min at a comparable welding depth. In stainless steel, the tests showed an increase in the maximum feed rate by +100 percent to 10 m/min.
Figure 2: Mass loss of the weld seam depending on welding speed for conventional laser welding with solid-state lasers and BrightLine Weld.
Figure 4 shows the mass loss of the partial penetration welds in stainless steel produced with BrightLine Weld in detail. To classify the results, the mass loss measured for conventional laser welding with solid-state lasers is also shown. Red data points again indicate an insufficient weld quality of the test welds. The conventional laser welding process shows an increased mass loss from a feed rate of 5 m/min. The mass loss of the weld seams produced with BrightLine Weld, on the other hand, is up to a feed rate of 20 m/min in a range which can be described as almost spatter free (< 0.4 mg/mm). At the same time, all weld seams made with BrightLine Weld show a high quality. Moreover, the seams have no humping up to a feed rate of at least 20 m/min.
Advantages Of Laser Welding With BrightLine Weld
The use of BrightLine Weld results in the following main advantages for the user:
Significantly higher feed rates at a constant seam quality increase productivity. In mild steel the maximum feed rate can be increased without difficulties by +300 percent and in stainless steel by +100 percent.
Minimal spatter formation and less contamination reduce cost of ownership. This results in a lower machine downtime, less rework of parts and lower consumption of cover slide glasses at the same time.
A lower laser power is required for the same welding depth. The high efficiency allows up to 50 percent energy saving at the same welding depth and at the same quality.
BrightLine Weld produces high quality weld seams. In favourable cases, weld seams do neither show undercuts nor end craters. Due to the reduced energy input the part deformation is very low.
How does BrightLine Weld work on real parts? This question is answered in the next section using a powertrain part as application example.
BrightLine Weld In Powertrain
A typical powertrain application is the welding of gear wheels. Depending on type, gear wheels are, eg, welded with a feed rate of 5 m/min and a laser power of 3.4 kW. Spatters which are generated during welding have to be exhausted.
For this application, the BrightLine Weld technology provides a significant improvement. Thereby BrightLine Weld can be used flexibly: either for optimising energy efficiency or for optimising machine productivity. If BrightLine Weld is used to optimise energy efficiency, the identical part can be welded at the same feed rate with a 40 percent lower laser power of 2 kW. With BrightLine Weld slightly slimmer weld seams are produced, which is why less laser power is needed to achieve the same welding depth. At the same time, the spatter formation is reduced, so even no exhaustion is required, hence reducing costs.
For those, who are more focused on improving productivity, they can also increase the feed rate at a higher laser power than in the state of art.
With BrightLine Weld the feed rate could be increased, eg, by up to 220 percent from 5 m/min to 16 m/min while still keeping the mass loss minimal. The result is a high quality weld seam at the welding depth desired.
In the future, BrightLine Weld should not only be used in powertrain, but also in other industries such as tubes and profiles.
Tubes and profiles are typically bent and welded from very long sheets (so-called continuous process). In contrast to powertrain applications, these welds are full penetration welds. Commonly, very high feed rates of, eg., 30 m/min are used, which cannot be achieved with solid-state lasers today.
These requirements increase the complexity but promising approaches could already be found. With BrightLine Weld, it is possible to produce full penetration weld seams at high feed rates, which meet the requirements.
The new technology BrightLine Weld has the potential to revolutionize laser welding with solid state lasers. BrightLine Weld allows for constantly high weld seam quality – independent of the welding speed. The user has the choice between optimising, ie, minimising energy consumption or optimising, ie, maximising productivity of his machine. In addition, the feed rate with BrightLine Weld is no longer a parameter which must be optimised. This makes parameter optimisation easier and accelerates process development.