Transcript
Speaker: you
Speaker: Okay, and welcome back to the third installment of the HFW Industries Technical Talk podcast. On the last episode, we had talked about HVOF coatings, and this episode, we will be talking about another type of thermal spray application, which is plasma spraying. Today, I'm joined by, again, our vice president, Matt Watson. And so, Matt, can you first dive into
Speaker: I guess on the different spectrum of thermal spray coatings, what will first what plasma spraying is and where it falls in that spectrum? Okay. Plasma spraying is when we are using ionized gas to form a plasma and that plasma is the heat source that melts the material and propels it against the substrate.
Speaker: So it's not a combustion process like HVOF. Plasma spraying in terms of the spectrum of coating technologies, it's a very high quality coating process. It's probably the most, I'm gonna say it's the most flexible process in that you can spray a number of coating materials, metals, ceramics,
Speaker: carbides, abradables, cermets. And in terms of overall coating quality, it ranks a little bit below HVOF in terms of bond strengths are typically lower than HVOF, porosity is a little bit higher, and hardness is typically a little lower, but still very high quality coatings.
Speaker: And so, uh, HVOF is, is a newer process, right? Plasma spraying has been around a little bit longer. Yeah. Yeah. And then, but, but that being so HVOF, I would say is kind of like the higher end application, but there are still applications where plasma spraying is best. Can you talk a little bit about the ideal applications?
Speaker: Well, for us, I mean, we use the plasma spray process spraying a bunch of different materials. Really, for us at HFW, the big difference is in terms of some of the wear resistance coatings, we spray a lot of ceramic.
Speaker: chrome oxide, aluminum titanium, aluminum oxide, and a lot of times those are wear and corrosive environments and you can't spray ceramics with HVOF. So right there,
Speaker: Right there, we depend on the plasma spray process to spray high quality ceramic coatings. You can do it with some of the older powder flame technology, but that's older technology. And those ceramic coatings aren't as hard or the bond strength's not close to what a plasma spray coating is. So for us,
Speaker: That's one big advantage of having the plasma spray process for us is the ability to spray ceramics. But we also spray a lot of metallic coatings. And we pick plasma spray. Generally, you can go a little bit thicker with plasma spray and the economics are a little bit better. So if we're spraying a large roll with stainless steel,
Speaker: And, you know, the customer wants a really good coating, but they want to spray it, you know, 40, 50 thousands thick. You know, that's where we may choose, you know, that's where we choose plasma over HPOF.
Speaker: Yeah, because HVOF has a lot of advantageous characteristics, including that you don't need to put a lot on for a strong coating. But I guess the negative side of that is if you want to go thick, you really, you can't really do that with HVOF or you have to, you should really do plasma. Well, for us, our experience is that you can generally, you generally can go thicker with plasma than HVOF. You know, HVOF, they're also two different
Speaker: you know, splitting hairs. But HVOF, you have kind of a first generation technology and you have a later technology, the kerosene based systems, where you can spray thicker than the first generation HVOF equipment. However, it's still more cost advantageous to spray a thicker coating with plasma spraying. That's been our experience.
Speaker: And then in terms of finishing, is there any difference between finishing a coating with plasma spray versus HUF or one of the lesser coating processes?
Speaker: Well, all the same rules apply. In certain instances, the coatings may not be as hard as HVOF, but all the same grinding techniques that you have to use finishing an HVOF coating apply to finishing a plasma sprayed coating.
Speaker: you know, whether you machine it, you know, some coatings we machine and some we grind and the rules of plot, you know, generally. You have to use the same, same or very similar techniques, finishing both classes of coding.
Speaker: And I guess this is more a comment for all coatings, but one of the benefits of working at HFW or working with HFW is our ability to one source all of this work in -house, which leads to typically a better quality assurance, right? When you're finishing or whether that's fish machining or grinding a thermal spray coating, doing that all in -house ensures
Speaker: number one we have the expertise but number two you're also getting that quality assurance of people that know how to deal with these coatings and have been dealing with these coatings for decades right. Yeah no that's an important point I mean that's that's really kind of been our one of our competitive advantages and there are I know of some shops who are strictly coating shops and that's prime
Speaker: Primarily, all that they do is coat, and any finishing of the coating would have to be done by another company. I know some grinding companies, their business is set up where they market that they grind a lot of thermal spray coatings.
Speaker: but they don't apply the coatings. For certain instances that may be fine, but here we're able to do the machining, to prep for coating, the coating, and the finishing of the coating. All of these processes really are tied together to give our customer that single source quality product.
Speaker: And especially in today's environment, it's also cutting down on lead time and cost as well. Well, yeah, it cuts down, it cuts down on lead time. And, um, you know, when the, when the part leaves HFW, after it's gone through the finishing process, you know, a lot of times, you know, people will ask about, um, you know, how do we know the, the
Speaker: our coatings are going to hold up and are they, you know, are they, how do we know they're bonded sufficiently? And we do do a lot of laboratory testing in -house, you know, we're doing photo, you know, we're looking at photo micrographs, checking, using image analysis, but really, you know,
Speaker: Finishing a thermal spray coating in essence is a good quality check you know cuz you're using either you know in in some applications or you're using a tool bit to turn the coating and others you're using a grinding wheel and you're you know you're applying some force and stress in that coating and if it and we've always told people if it comes through the
Speaker: If it comes through the finishing process, at the very least, you know that you've got a good bond right there if it's come through the coating, the grinding process.
Speaker: Yeah, I think with our facility, I'd say in most cases too, our quality control and our quality processes, we also probably err on the side of doing too much inspection and too much quality control, which leads to a really sound product as when it ships out to our customers. Correct, correct. So, I mean, is there anything else you'd like to add in our discussion of plasma spraying today?
Speaker: Well, really, just that it's a very, I look at it as advantageous to have this process in -house. It's the most versatile process. It gives us a lot, as I said, we're spraying on a weekly basis. We're spraying metals and ceramics with the plasma spray process. Some carbides, and then we get into abradables from time to time as well. So it's a very versatile process.
Speaker: And it does provide a very high quality coding. OK. Well, I think that pretty much wraps up our conversation on plasma spraying coatings. Matt, for anyone that's looking for more information, where can someone go if they're looking to hear more about whether it's plasma spraying or comparing HVOF and plasma spray? Where can someone go for more information?
Speaker: Well, they can certainly contact us if they have an application that they're wanting to discuss and whether it would fit plasma spray process or HVOF process. And there's also a lot of good information out on the web. I know a lot of, there are a lot of sites out there that do a nice job of presenting some of this data as well.
Speaker: Yeah, including our website, which will be updated very shortly too. So I had to get that plug in there. All right. Well, that concludes our discussion on this third episode of our technical talk series, this one on plasma spray coatings. We will see you on the next one. Thank you.
