Designed for light
In some circles now the laser might almost be considered a commodity manufacturing tool; in others its use is still thought of as a bit of a black art requiring specialist knowledge. The work that goes into building a laser machining solution can vary enormously, depending on the task, so how do you get the best out of a laser and what questions should engineers ask system integrators when deciding on the production process?
‘Integration always starts with the end point,’ commented Dr Geoff Shannon, manager, advanced technology at laser system maker and integrator Amada Miyachi. This can then be broken down into the application and system needs in order to fulfil the production requirements.
‘Sometimes our customers come to us with a clear idea of the solution they have in mind; even the laser source is specified,’ commented Uwe Wagner, chief sales officer at 3D-Micromac. ‘In these cases, the customer generally does the process development. In other cases, we have to choose the laser source, the motion system, the optical beam path, and other components. There are also economic considerations for production systems, so it isn’t just the quality of the processing that’s important, but also how cost-efficient the system is in terms of investment as well as cost of ownership.’
3D-Micromac, based in Chemnitz, Germany, is a laser micromachining company offering standard systems, complete production solutions, and customised systems.
The integrator needs not just to have knowledge of laser technology, but also mechanical and electrical engineering, and often software programming. Thilo von Grafenstein, marketing manager at Acsys Lasertechnik, a provider of laser machines, commented that a good laser system integrator should have knowledge of all these disciplines and how they interact with each other.
Shannon noted that most of the time it’s a collaboration between the integrator and the end-user. ‘It’s hugely beneficial for an integrator to have a solid understanding of the application, as opposed to purely making a machine to a specification. In many cases, the end-user doesn’t have sufficient understanding of the laser technology and system features to define a specification fully. It’s hugely beneficial to be able to lean on the integrator to choose the right laser and optimise the laser parameters to create a system that will work.’
He continued: ‘It’s beneficial for the end-user to have a little bit of understanding of what they’re trying to do so they can ask the right questions. What laser am I going to use for this application? That’s a fundamental question. Then, how do we engineer the process? Does the part move? Does the beam move? Do both move? Those are all things that the customer needs to consider. Price and delivery are part of it too, but the customer needs to hear answers to those process questions from the integrator’
There’s always a best way to build a system. ‘Every integrator should strive towards simplification of a system,’ Shannon said. ‘If the integrator isn’t familiar with the application or the production environment they are less likely to come up with the right decision. The best route to achieving a good solution is to work with an integrator that really understands the application and the production environment.
‘You want to have a dialogue with the customer and for them to be involved in the process. The customer shouldn’t be totally reliant on the integrator to provide the best solution. They should question the integrator, understand why the integrator is making certain decisions. If the customer is invested in that process, it’s going to help him understand how the integrator makes the decisions, and it’s going to ensure the integrator justifies its decisions. Those two things together normally result in a good solution.’
The throughput challenge
‘Maximising the productivity of a system comes down to minimising the overall cycle time,’ explained Shannon, adding that this includes loading and unloading the part as well as the processing time. ‘That might relate to the application, the part loading mechanism, or the stage or optical train – do you use a stage, a galvo scanner, or a gantry system to process the parts?’
He added that the end-user has to be realistic about the production throughput. ‘You want your integrator to offer some common sense as to what is achievable and what isn’t,’ he continued. ‘We try and guide the user through the process and educate them so they can make the right decisions. We want to have a dialogue throughout commissioning and building a laser machine to make sure the user is educated, on board and part of the process, so that when the machine arrives there are no surprises and everyone understands what the machine is supposed to do and what it is not going to do.’
Tooling is another consideration and a big part of laser welding tasks. One question the integrator might have to ask, according to Shannon, is: how can the tooling be used to minimise cycle time so that the part is positioned, clamped, and welded as fast as possible and reliably?
Amada Miyachi deals with laser micromachining for which the production environment can vary significantly. ‘In laser microprocessing, every system we make is customised to some level, typically because the parts and application requirements are very different from customer to customer,’ Shannon noted.
‘In microprocessing, the shapes of the part might differ and that might influence how you hold the parts and how you get the beam to the weld location. The material might differ, as might the function of the weld – all those things add up to a machine being customised to some degree. Thirty to 40 per cent of our systems are completely custom built,’ he said.
Wagner at 3D-Micromac commented that, in the past, enquiries for laser micromachining were quite specific and high-end, whereas now the laser as a micromachining tool is becoming more commonplace.
‘Lasers are now easier to use,’ he said. ‘Software and an accessible user interface helps with this, but also the stability of the laser itself; the optical integration is easier, and you need less metrology to make sure the laser is doing the right job. It’s opening up new applications and this will continue to be the case in the future.
‘Use of the laser is not a bottleneck anymore,’ Wagner continued. ‘But the intelligent integration of the laser into the system improves the capability and efficiency of the tool. Applications require know-how in machine integration and machine setup, as well as how to use the laser. The laser is just a module; aspects like tooling that surround the laser define the laser’s capability.’
3D-Micromac’s laser structuring tool for laser contact opening of solar wafers is a good example of intelligent integration, according to Wagner. ‘The most expensive parts in the system are the laser in combination with the optical beam path. A good integrator should find a solution with minimal additional components that keeps the laser up and running for almost 100 per cent of the time,’ he said.
The company developed a handling component that works in a similar way to a processing stage. The solar cells are transported under the laser source on a conveyor belt, which avoids alignment stops. The integrated optics automatically compensate for the cells’ relative motion and the laser scribes exactly the desired pattern into the back of the solar cell. The on-the-fly processing gives almost 100 per cent laser uptime, Wagner noted.
Making a mark
Laser marking machines are much more of a commodity piece of a equipment than the systems developed for micromachining, but installing a laser marker on a production line can still require the expertise of a system integrator. Aaron Grimes, global product line manager at US-based laser marking company Tykma Electrox, gave the example of an automotive customer installing a laser marker in a station for leak testing components. The laser is there to mark the part with tracking information once it has been tested and verified.
Integrating a laser marking solution on an automated production line follows the same guidelines as designing a system for micromachining, in that the starting point is the application, noted Grimes. ‘We want to know the type of component being marked, the material, the details and requirements of the mark, and the available cycle time,’ he said. ‘The difference between a 20W and a 50W laser usually comes down to cycle time.
‘Once we qualify the mark, know what wavelength of light is needed – most of our applications are solved using 1,064nm light – and determine that we can make the mark within the cycle time, then we know reasonably well what laser model to use,’ he continued.
The next stage is the control command to the laser, which is usually a trigger from a programmable logic controller (PLC). The data exchange is another consideration. ‘Most of the time in an automated application the data varies from part to part, usually either serialisation or date coding or custom coding,’ Grimes said. ‘Even in a test station like a leak test, sometimes they’re marking data from the test on the component – so the code contains proprietary data. We then have to understand how that information will be sent to the laser and via what form of communication.’
Tykma Electrox provides a lot of pre-set capability to communicate between the laser and the production machinery. The company offers off-the-shelf solutions for the customer to get the marking data to the laser in an integrated environment.
‘The goal for us is to make off-the-shelf solutions available for data communication between the laser and outside sources. That’s a big deal,’ commented Grimes. ‘A lot of companies offer solutions but they require heavy customisation that might be tedious to learn, or require a higher level of programming. We try to simplify that.
‘Sometimes we need to look ahead to the future. We need to think about volume, whether the volume of parts to mark will increase. We also try to match the customer’s needs with economics,’ he added.
‘The winning combination overall is to make a laser that’s reliable, easy to integrate, but also remaining cost-effective,’ Grimes continued. ‘Laser marking is becoming more of a commodity and more standardised in a lot of factories. The prices of machines have been dropping steadily over the last 10 years. It’s become competitive, so the key is to offer customers a cost-effective solution while still giving them a quality piece of equipment, and good service support.’
Grimes’ advice for successful integration is to try and keep it simple. ‘We see certain solutions that are more complex than necessary,’ he said. ‘It’s easy to do this if an integrator hasn’t had a lot of experience with laser marking. We try to educate the customer on solving the application in the most cost-effective manner.’
Shannon commented that the use of laser machines will get easier, just in terms of software and interface advances to help optimise processes, but that for the integrator it doesn’t get any easier at all. ‘There are many more lasers on the market and you have to keep up-to-date with the technology,’ he said. ‘There are also advances in motion and different optical technologies that you need to keep up with. This means the end-user will still have to rely on the integrator to a large extent to help them through the process of building and installing a laser system.’
Safety first Phil Jones, marketing manager, Lasermet
One of the many priorities under consideration is the safety aspect of the laser. This should never be overlooked, although it may not be the immediate focus of attention. The provision of a certified laser safety enclosure or cabin, complete with an integrated laser interlock control system, is as much a part of the working system as anything else. The ideal laser interlock controller is rack mounted on a DIN rail system and located in the cabinet containing the other main laser system controls. Combine the controller with automatically operated laser safety cabin doors, HD CCTV and HD monitor, or active filter windows and then connect to an interlocked laser fume extraction system and you have the complete integrated laser control system.
The system must be certified as being safe, so the provision of a Class 1 cabin for Class 4 lasers is the practical solution. The cabin that houses the laser should be considered as part of the control system as it contains the laser radiation. Usually, stray laser radiation is absorbed by the walls and roof of the laser safety cabin, but with the advent of even higher power, multi-kilowatt fibre lasers, it is now also necessary to include active laser guarding as a means of laser radiation control. Inadvertent laser strikes on the walls of the enclosure, caused either by reflection from the workpiece, missed or damaged targets, or control errors can all be catered for and rendered safe in an integrated laser safety control system where active laser guarding is included. Here, wall or roof strikes are immediately detected by the laser interlock controller and the laser switched off within a few tens of milliseconds. As the safety function is completely automatic for passive or active laser guarding, the operator can concentrate on performing the laser work in hand and continue to get the most out of the system.