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In the last blog of our series that focuses on key steps and challenges in laser process development, I explained three common mistakes in selecting laser. Now I want to talk about how we approach this early phase, which we call Phase One in our methodology when we work out what's the right type of laser. There are the 10 steps I typically follow on an application to application basis. Step 1: Articulate the application One way I like to do this is to listen to our customers’ big picture, product vision, and the process needs. And then I like to re-articulate what I learned in the form of a document that describes this problem-and-needs statement. And if our customers think that we've grasped this problem correctly, we move on from there. If not, then we discuss it more, identify the misalignment and redo the document until there is good alignment in our understanding of what their needs are. Step 2: Review the materials Carefully review the materials that need to be processed. Now, sometimes it's just a single material. It could be a wafer of glass or semiconductor. Sometimes it's a complex medical device where there may be five or six different materials that laser might come in contact with, or a display panel where you have multiple stacks of materials and you might want to process just the top material and the bottom materials or vice versa. To understand the materials better, find out: how many materials the laser is going to process? what is the proximity of the laser to other materials and the devices what are the wavelengths that these materials are going to absorb or transmit what are the thermal properties of these materials what are the mechanical and chemical properties of these materials Step 3: Know the deal breakers By identifying what type of byproducts or features defects are deal breakers, applications engineers can now have boundaries to this very large process space. For example, if you find out any type of slag, burr, micro crack or anything like that is an absolute deal breaker, then it kind of pushes us towards a regime where we need to work with short pulse lasers as a potential solution, or maybe working with ultraviolet laser, or maybe we can get away with another laser as well, but we would need to make sure it does not yield any of the deal-breaking defects. Having these boundaries can help save money. Typically, an absolutely perfect result requires a very expensive and slow solution. A lot of the times, we will have to go down that route when asked, then find out that really at the end of the day, the end application can tolerate having some microscopic defects in there if another process can be two, three, four, sometimes even 10 times cheaper as a return on investment. So clear articulation of the deal breakers is important. Step 4: Understanding throughput needs Work out the throughput requirements and find out why the throughput requirements are set up that way. I like to challenge these numbers all the time and work out what's driving throughput requirements because misleading statements in this place can mistakenly eliminate potential solutions that might be a great fit for your application. And there're many ways to scale throughput with lasers systems -- from multiple heads, multiple lasers, splitting the beam into multiple focal spots or just running at a higher power with faster beam delivery systems. Being mindful that this phase isn't trying to work out how to make everything fast and perfect is important so to not be discouraged or distracted. It’s worthy to note at this early Phase One, the process can be super slow. Being mindful that this phase isn't trying to work out how to make everything fast and perfect is important so to not be discouraged or distracted. Remember this phase is about working out what the right type of laser is and then using that as a platform to get to where you need to be. The important focus at this stage is to evaluate quality and identify pathways to speeding things up. Having said that, there are some applications where speed is everything, and if you know that it is not financially feasible at a certain speed, for example one part per minute, then it's good to communicate that early on and have that as one of the deal breakers (Step 3). Step 5: What are the part or material tolerances? Now, I'm not talking about tolerances to the processes as those are identified early on in Step 1.What I mean here is the material that you would put into the machine or the product that you've developed that you put into machine--what are the tolerances on this? Something to note is that in general, most industrial lasers have extremely low variability, which means that the power, the size of the laser beam and all the key parameters that determine the process are very, very robust. Where we see most of the variations that happen in processing are caused by the materials or parts themselves--for example, the flatness of the materials or how well aligned the materials are to certain features. A lot of processes can show variation(s). For instance, in laser drilling, you may drill a bunch of holes in your material, and find the exact size of the hole varies quite a lot. You’d find often that this is caused by the material which can be its density, flatness, thickness, surface smoothness, or even how debris is being handled etc. If we look at laser welding, variations can happen based on how well the material is assembled ahead of time, how well the two parts to be welded together are placed in contact with each other, or the cleanliness of the material and the presence of defects. So understand what the tolerances are going to be on the material and it's important to know what these tolerances would be like in a production environment. Sometimes the parts that we get in at an early stage have been handled many times before they come into our facility, and they've not been done in a nice production environment. And so we're working with parts that are a lot dirtier than you would have in production. So this could present challenges. Sometimes it's the opposite. Sometimes production environment is actually really dirty and the parts that we're getting in have all been handled in a clean room. And now the parts are too clean in that regard. So it's good to have an understanding what the production environment is going to be like. Step 6: Research laser prior arts Step 1 to Step 5 are guidelines on how to hold theoretical discussions with our customers so that we can have a deeper understanding of the requirements. Once that is established, it is now a good time to look at what's been done in the past. At this point, we look to our knowledge base through the following: we look into applications we've run before we consult with our applications engineers and lean on their expertise. we talk to our laser suppliers and learn from what they've learnt from in the past. we research through published literature. One virtue of the laser industry is the strong community of both industrial and academic publications out. There’s much we can lean on to learn from the fundamental basics that are published. Also it's really important to avoid draw conclusions too quickly. This step is as an exercise to mine possibilities and ideas as a start. For instance, you may find applications that had drilled 50 micron holes in borosilicate glass, but it’s important to know that you are not necessarily limited to the same features or results. Another example: you may find applications that drill one hole per minute, but there may be other beam delivery or laser systems that can speed things up. To sum up this step, stay open minded as you learn and focus on understanding the fundamental laser material interaction and compatibility. Step 7: Identify laser candidates Form a general idea on what types of lasers could be potential candidates. Start reviewing the process requirements (Step 1 to 5), thinking about beam delivery, or talking to your applications engineer about beam delivery. The choice of the beam delivery and how you use the laser can be the difference between getting an amazing result and having a complete failure. And often the difference between those two can be a choice of lens, the gas pressure that's used in a gas head, or maybe other subtle process nuance related to part fixtures. Step 8: Design of experiments (DOEs) We've finally got to a point now where we're running experiments in the lab, testing out different laser types and laser setups. One of the most important things to apply here is running experiments that vary the key parameters and look for trends. Now, this is basic scientific methodology, adjusting one variable at a time, and looking at trends when that variables is adjusted. Most laser labs have PhD-level applications engineers and scientists running these applications. But it’s also very common that good scientific methodology isn't used, either due to lack of staff or time constraints. Most laser labs have PhD-level applications engineers and scientists running these applications. But it’s also very common that good scientific methodology isn't used, either due to lack of staff or time constraints. Even though this stage is basically a simple test, it's pertinent that DOEs are set up and processes are adjusted in a way such that when you're comparing these process regimes, you understand the trends and how they came to be. Whether you're just trying to look at the dependency of laser power, wavelength, beam delivery, or even comparing two completely different types of lasers, you need to analyze the results in a way such that: 1. it makes sense 2. you're able to learn about these trends 3. you understand how specific parameters are affecting the process. The emphasis in this step is to look for trends using good scientific methodology. Step 9: Configure optical beam delivery Make sure that the beam delivery and optics are set up to be in the right regime. It's really important that you have the correct focus conditions to get the result that's required and defined by the process needs. It’s good in this step to do some calculations. Maybe look into some of the background work that has been done that will help identify the sort of optics conditions you need to work in. I have learned that some applications are a lot more sensitive to this than others. Good examples are glass cutting, glass welding, or applications where focusing conditions are absolutely critical, and they can make a difference between a working process and a complete failure. There are some applications such as hole drilling, where the size of the focus is going to be super critical as well. Besides working on achieving the process, it’s also helpful to be mindful of practicalities like material handling and flatness from part to part. While you might not be trying to solve these problems in Phase One, you might be running into some issues if you come up with a solution in Phase One that absolutely relies on a specific optical setup which proves to be impractical in volume production and integration with automation. So just having some sort of awareness about those limitations is important here. Step 10: Review. Refine. Report. Now it’s time to take all these results and review them together with both the laser supplier and the customer to identify areas where the process can be improved, where it looks to be satisfactory, and to determine if you found a regime that has the potential to pass all of the deal breakers and meet the specifications. It's at this last step where I compiled all the lessons learned into a report which we discuss together and create appropriate action plan for Phase Two – a phase where we attempt to make the parts to specifications. To conclude, determining the right laser, which we call Phase One, is a great opportunity to create a space of solving your application requirements. By avoiding the three common mistakes I mentioned in the previous blog, and by approaching Phase One from a methodical scientific approach (the steps in this article) with experts in this space can lead to significantly better results, faster and more cost effective way of achieving overall success. I hope this blog post is being useful for those who are interested in laser manufacturing, laser process developments, or just want to learn about how to get into the space. If you have any questions regarding phase one, or how to approach it, please reach out to us. Next blog post will be on phase two, which is making the part to spec, so stay tuned. About Mark Turner Mark Turner holds a PhD in laser machining and is the founder of Turner Laser Systems LLC with over a decade of experience working with lasers. Laser physicist by day and an avid coffee maker by night, he's known to be brewing the perfect cup of espresso for his friends at his home in Fremont, CA when away from work.

In the previous article, I talked about how to choose the right partner to support your process and integration needs at the very early stage of discovering laser as a potential solution to your product development or manufacturing needs. In this article, let's talk about one of the most common and important questions that we get asked all the time, which is “what's the right type of laser for my application?” And this question is asked in many different ways: what type of laser is best to be used? What type of laser is best to be used?ser? Should we be using CO2 or UV or infrared laser? Should we be using a fiber laser or a solid state laser? Can it be done with the laser? One of the biggest challenges I see when people are trying to address this question is knowing the best approach to this question. In our methodology at TLS, we refer to this early laser feasibility stage as Phase One. There are steps on how to approach this methodically, but in this article, I will first focus on the three common mistakes that people make time and time and again. In my observation, these missteps, though unintentional, can cost companies a lot of money and waste a lot of resources, which ultimately lead to major delays as well into product development and/or manufacturing -- sometimes by years if this isn't approached in the right way. Mistake #1 Not Being Transparent While it’s important to protect your IP, it’s important for the laser expert to have a full understanding of your application, even at a high level. Laser experts or engineers can best solve your production problem, your manufacturing problem, or your product development problem when they understand clearly how the problem fits into your product, the reason for the process, the purpose of the feature and how everything affects your product – the big picture. A good laser applications engineer should then be able to translate these high-level requirements and information you provide into a process specification, and that in turn will translate to developing the actual process that serves your needs. At this early stage, it's important to be open minded and creative in your thinking of a solution. It is also critical for both parties — the laser applications engineer and the customer/end-user -- to take the time to educate each other. Doing this can save a lot of time from boxing yourself into an inefficient solution right from the start or coming to the wrong conclusion based on incorrect assumptions. When we receive very specific process specifications from customers – let’s say a specific feature with “this much” tolerance or it has to be “this exact” throughput etc.-- often what we do is challenge this and ask for the big picture because we need to make sure there's an alignment between the process specification and the intention of the process. An example would be a frequent request for chamfers to remove edge defects for the purpose of improving the mechanical strength of a CNC machined part. However, in laser processing, sometimes (not always) a chamfer can be skipped because laser cutting can have a quality that’s good enough to not require post-processing. In this example, the education between the two parties can help determine if a chamfer is necessary. There are many other examples of technical specifications, such as tapering of certain features. Typically, laser cutting, ablation, and drilling methods have a sort of taper angle to them. With some education to the customer early on, a laser application engineer can help them understand different types of limitations to the various manufacturing processes. The customer can in turn educate the laser expert on the true needs for the application. This production exchange can then help determine the degree of tapering appropriate for the application. Mistake #2 Shooting in the Dark Another common mistake we see is trying out different lasers randomly without any deep thought or understanding about what laser was chosen, how it was used and what you learned from initial testing. Good example here is you go to Shop A, B and C testing three different types of lasers. You may not know exactly what type of laser it is or how the lasers are set up. And you get: bad result from Shop A bad result from Shop B OK result from Shop C At that point, you have not gained a clear understanding on what works and what doesn’t, and why bad results vs OK results, or even how to get better results. All you know is that in Shop C, they got an OK result, but you don’t know how it’s going to translate. I've developed some really powerful laser process solutions for companies over my career and the more applications I've worked on, the more I realize that process development takes time. The main thing to remember here is that just because one test, one supplier, or one laser may be a complete failure – or even sets your part on fire, it doesn’t mean there is no hope for a different laser out there to be the perfect tool for your application. Mistake #3 Not Doing Enough Homework A frequent mistake that is not often talked about is the urge to draw a conclusion before enough work is done. Customers often want simple answers asking, “is this the right laser for the job?” and an expert will reply, “it depends.” Laser process development is complex and it’s important to refrain from jumping to conclusion on whether a laser is the right laser without understanding the difference between the fundamental laser-material interaction, which is typically related to the laser type and the laser process, which is related to how that laser is being utilized. Often a right laser doesn’t seem to be doing the right job until the correct parameters are dialed in, and determining the right parameters requires an expert. For example, you can have a super expensive $1M state-of-the-art ultrafast laser machine and your material could still catch on fire, even though you've invested in this very fancy and advanced laser tool. You may then want to determine that this is the wrong laser for the job, but it’s important to refrain from judgement, as the devil is in the details. Laser systems, especially micromachining laser systems with pulsed lasers, have a lot of adjustment capabilities. There are so many knobs, dials and parameters that you can adjust that the process space is actually extremely vast. To help illustrate this better, I've spent 100 hours on an application where I've been dialing these knobs, trying out different configurations, and every single part came out looking absolutely horrendous. And it wasn't until hour number 101 where I started to get a result that looked like the solution was viable. Sometimes we can get contrastingly different results just by adjusting these parameters in finding the right process regime. It’s not always that long and tedious of course. Sometimes we run applications where after 30 minutes we've hit bull's eye. So it really depends on the application and the complexities of the process and the materials. In summary, to avoid these common mistakes, remember that good process development requires expertise in the field, deliberation, and persistence to be successful: tests should be well-designed and purposeful to fit the big picture, so that findings can be meaningful as learnings, and a process to be developed methodically with persistence for the right result. Of course, avoiding mistakes is just the start. In my next article, I will list steps that I use in working out the right type of laser. Please follow us on LinkedIn for our next blog update or subscribe to this blog. For immediate answers about laser processing and applications, email us at info@turnerlasersystems.com. To see Turner Laser Systems or laser processes videos, visit our YouTube channel. About Mark Turner Mark Turner holds a PhD in laser machining and is the founder of Turner Laser Systems LLC with over a decade of experience working with lasers. Laser physicist by day and an avid coffee maker by night, he's known to be brewing the perfect cup of espresso for his friends at his home in Fremont, CA when away from work.