MANUFACTURING HEAT TREAT

Heat Treat Today publisher Doug Glenn and Marc Glasser of Rolled Alloys on why choosing the cheapest material is not always the best way to go. Listen to some of the practical tips Mr. Glasser gives for choosing the right alloy for your application.

Below, you can either listen to the podcast by clicking on the audio play button, or you can read an edited transcript.

 

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The following transcript has been edited for your reading enjoyment.

Doug Glenn (DG):  We're going to talk today about something that Marc and I had talked about that kind of caught my attention that I thought might be of interest to our listeners, and that's this whole idea that sometimes buying the cheapest material isn't always the best option.  So, that's the topic, but, before we do that, Marc, I want you to tell our listeners and/or viewers a little bit about yourself, your background, and what you're currently doing.

Marc Glasser (MG):  I have been a metallurgist or material scientist for forty years.  Next month will be exactly forty years since I graduated from Rensselaer Polytechnic Institute with a bachelor's degree in materials engineering.  After ten years of working, I went, simultaneously, to a job and to night school for five years and I obtained my Master of Science in material science from, then, Polytechnic University which is now known as the NYU School of Engineering.  I've been working in all areas of metallurgy and material science.  I've worked in rolling, I've worked in forging, I've worked in powder metallurgy, and I've worked in heat treating laboratories.  I'm currently working in metallurgy of heat resistant materials and applications of these alloys in industry.

DG:  Let's jump in then, Marc.  I want to talk to you a little bit about this contention that you and I talked about that sometimes, but not all the time, expensive is better and buying the cheapest isn't always the best.  In a nutshell, what are you trying to say on that?

MG:  I'll take it even one step further:  Expensive is cheaper.   Let me expand on that.  You have a part and it's a certain price and you know you have a life of two years. . . so that's cost X.  You have alloy #2 that's going to cost 60% more.  It's going to have a life of eight years.  Again, you're going to pay 60% more for this part than you would for the first part of the less expensive alloy.  But, over the operating life of that less expensive alloy, you're going to have to replace it three times.  You're going to use four separate components.  So, 60% of the cost times four, you're spending 240% more than you would spend on one component that's a little more.

It's cheaper up front, but over the entire life cycle of the part, buying four more parts of the cheaper one is a lot more expensive.

DG:  Let's talk about some of those hidden factors that come into play when you're analyzing the true cost of selecting those materials.  Do you have a couple of examples?

MG:  Absolutely.  The most stark example, that we made our first case history on, is radiant tubes.  For years, the alloy of choice on radiant tubes was a wrought 601 thin wall and you get about two years on it in a typical furnace.  Then the casting industry came in and, because of limitations of the machinery, they had to go with a heavier wall that was three times as thick and that cost 30% more, but it got four years of life.  Now, there's newer technology and they can cast it a lot thinner, but thinner doesn't last as long.  So, for the wrought tube, you're talking about 1/8 of an inch wall thickness.  With cast, for the four-year version, is about 3/8 of an inch and if you go down to 1/4 inch or less, you get maybe two or two-and-a-half years and if you go to the more expense wrought alloy, (again, you're talking about 1/8 inch wall), it's 60% more than the original one, 30% more than the cast, and you get eight years out of it.

Now, again, these numbers are based just on the cost of the material.  But, you've got to dig a little deeper because you're not capturing the true savings of using the more expensive material because, think of this:  If you've been in a heat treating shop and you know your carburizing furnaces, you have to turn it off, cool it down, let it air out because you've got a carbonaceous gas in there and any residual carbon monoxide, if you go in there, you're going to asphyxiate.

The bottom line is, the turnaround can take up to a week.  Each time you have to go down for a week, what everybody doesn't even think about is how much revenue in sales and/or in profits are you losing from that week down?  And, if you're going from cast to the better wrought alloy, you're talking about one week.  If you're still going with the original less alloyed, thinner wrought tube, that's three times.  Those savings can be much larger, depending on the facility, than just the material cost; it's just a few thousand dollars.  I don't know how to evaluate how many tens of thousands or hundreds of thousands of dollars of lost production would be, but each shop has to consider that.  They know the numbers; those are proprietary numbers that need to be considered.

With muffles, it's the same kind of analysis because you have the same alloys except muffles are not typically cast.  But, let me give you an example.  A lot of muffles operate at 2125 and, again, you use a 601 muffle.  They're going to stay perfectly straight and flat at that temp for about six months.  At that point, the typical shop will start seeing a little bit of roof sag and it will sag more and more and more.  But there's plenty of room, so you can get a lot of sag before it starts interfering with the parts being conveyed.  So, my general rule from the shops that I've seen, is that it can sag for about three times as long as it stays straight before the sagging is too great and has to be removed.  Typically, it's about two years.  With the better alloy, again, the case that I've seen was two years without any sagging and that was a higher temperature.

What we've done is we've actually gone to good customers who understand the concept and we work with them on developing case history.  They log in when they put it in and the log in when they take it out.  They have good records, number one.

Now, I'm talking predicted metal temperature based off the process temperature which could be more or less because it's estimated.  But I know that the one that we looked at was at least 2200 on the metal temperature.  And this was one of the really crazy ones because it was replacing a cast material of much higher quality cast material and the cast material was dead straight for a year-and-a-half, it would start to just creep a little, but if you're familiar with casting, there's not a lot of ductility in casting when it starts creeping maybe 3 or 4%, you don't have to worry about more creep; it ruptures!  Then, the gas starts escaping and that's no good so they take it down.  In this case, when you switch from the cast, the best wrought material was actually cheaper and it lasted longer and the particular customer would just change them every two years because they were still in cost savings mode.  Based on my experience, I've predicted that they should be able to get at least six years on it.  But, they're not willing to take that chance.

DG:  The examples that you gave were the radiant tube and the muffles.  I assume the same thing would be true, though, in retorts, for baskets or even fixturing systems, and things like that.

MG:  Absolutely.  I bring those two up because I have more good case histories.

DG:  I assume the same would be somewhat true for fans, and things of that sort, if necessary, although you wouldn't be worrying so, so much about sagging and stuff like that.  But anything, basically, I assume, metal.

MG:  That's correct.

DG:  How about measuring the life cycle of materials components?  Any tips or tricks you've got for people on how exactly to do that and to get an accurate estimate?

MG:  What we've done is we've actually gone to good customers who understand the concept and we work with them on developing case history.  They log in when they put it in and the log in when they take it out.  They have good records, number one.  We've worked with others who've wanted it to work but they didn't do so good of a job tracking it.  In one case, it was a much larger furnace where they had many radiant tubes and they were just working with a few of them.  Personnel changed – one person didn't let the next person know about the trial and the identity got lost.  So, we spent a lot of time for nothing.  But, what we learned on that one is something real simple:  You take a welder and you weld the alloy name somewhere on the tube and that's not going to wear away.  Assuming you choose the right consumable, that weld is not going to go away.

DG:  You already gave a couple of examples, but let me ask you this:  How about a few concrete examples of where a more expensive material produced an overall more cost effective part?  You already kind of gave us those back with the radiant tube, but are there any others that you've got along that line?

MG:  The radiant tube is a great example.  Muffles and retorts.  We've been trying to work with some people on larger heat treating trays, but, again, there the task people have done a pretty good job, so we're trying to find a few people willing to go out on a limb and try something better.

Here, the concept is the idea of something lighter so that we don't look as much about the cost of the component.  If you go with a lighter fixture, your furnace has a weight capacity and if you cut your weight 20-30%, you can put more parts on it and have more of your furnace BTUs going to heat treat parts instead of fixturing.  When you're putting BTUs into parts, you're talking more profit per part.

DG:  Right.  You're not spending as much time, basically, using a basket as a heat sink, or something like that.

MG:  Exactly.  And, that's a concept that I introduced at one of the conferences about a year and a half ago.  These things take time to percolate before they're accepted by people.

DG:  Speaking of acceptance, let me ask you this question:  Are these concepts that we've been talking about, the idea that sometimes less expensive is not better, is it widely accepted, do you think?  I mean, do you think people understand it, generally speaking?

MG:  Some people do.  Not as much as I'd like to see!  The other obstacle you're looking at is when you're looking at four years versus eight years and you look at some of the larger companies, you may have personnel turnover and one person doesn't want his 'replacement' to get all the credit.  These are things that were learned the hard way.  You have to get the right people to try it.  A family-owned business is a perfect place.

I can give you another real good example on heat treating baskets where it made a difference.  I'm going to give the name because I have done papers with him at a conference on this subject so I don't think it's taboo.  I work with Solar Atmospheres on a basket for an extremely high temperature heat treating process that was slightly under 2300 degrees Fahrenheit.  (We can say that because it's in the case history.)  The first baskets that he used were your traditional Inconel 600 601 and they were supporting heavy parts.  After five cycles, they had to cut all the sides off, hand straighten them (each of the sides) and  weld it back together.  That's timely.  So, he went to another alloy, a better alloy, a competitor's alloy (HR120), and got ten cycles on it.  He was very happy.  Then, one of the people at their headquarters heard me give a talk on this new alloy that we had, our 602CA, which we trademark as RA602CA, and he got excited.  He started asking me questions after the presentation and we eventually got kicked out of the room because it went well beyond the break; so we continued out in the hall as we walked to our company's booth and we talked.  It took about ten to twelve months before they were ready to try it.  We worked with their fabricator to get the material.  They were up to forty-five cycles before they straightened it and there's a catch, though, to that.  At forty-five cycles, they probably could've continued, but during the pandemic in 2020, when things were slow, they made a smart business decision that this would be a great time to do the straightening.  I can't fault them, but it would have been nice to know just how many more.  But, at forty-five versus ten, it is probably a similar cost at the time of manufacture.  That's a no-brainer.

DG:  So, we've covered some of the basics.  We understand that it's not necessarily widely accepted so people should pay attention to some of these things that you've said.  Are there any other economic factors that you think people aren't necessarily taking into consideration when they're doing material selection, besides the things we've talked about.  Initial cost, life cycle, cost of replacement, and those types of things.  Is there anything else that they ought to be thinking about?

As I mentioned in one of the cases, when there is significant down time to replace a part, you've got to consider how much money you're not bringing in because you're down for a week, or however long it is.  This is often overlooked, as well.

MG:  As I mentioned in one of the cases, when there is significant down time to replace a part, you've got to consider how much money you're not bringing in because you're down for a week, or however long it is.  This is often overlooked, as well.

DG:  To me, that's cost of replacement, because that's not just a hard replacement cost, but the downtime replacement, right?

MG:  It's a little less obvious, though.

DG:  Those are all good thoughts, Marc.  When people go to do material selection, keep some of these things in mind.  It's not just a matter of what the buyer, the purchaser guy, sees coming across his desk and comparing those two costs, let's talk about the material properties and longevity of the product and things of that sort.

I know that you, being with Rolled Alloys, you guys help customers, I imagine, pretty much continually on things like this.  If people want to get in touch with you or Rolled Alloys, how is it best to do that?

MG:  There are a couple of ways. The first way is my email: mglasser@rolledalloys.com.  You can always ask me a question.  On our website, there is a link to ask a metallurgist a question.  I believe, you can also go www.metallurgical-help@rolledalloys.com and that will bring you to one of the metallurgists in my department and somebody will get an answer to you .

DG:  Thank you very much, Marc.  I appreciate your expertise.  We'll hope it's helpful to the heat treat world.

MG:  Doug, I thank you for having me as your guest and I look forward to more conversations with you.

 

 

 

 

 

 

 

 

 

 

 

 

 

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