The STLE Compass Podcast, Episode Three:
Metalworking Fluid Management with Dr. Don Smolenski, Technical Fellow at General Motors, Research & Development

KARA: Hello, I’m Kara Lemar. Welcome to the STLE Compass, brought to you by the Society of Tribologists and Lubrication Engineers. The STLE Compass is your convenient and reliable resource for the latest industry developments.
This is Episode Three of The STLE Compass and today the focus is on metalworking fluid management. Metalworking fluid management starts with choosing the right fluid which will perform best in a given application. Preventing its failure is critical, but one must also understand its failure mechanisms because that information is beneficial to all those who use it since they play a role in its care. Prevention methods keep the fluid at its best thereby producing quality parts, lowering the risk of rancidity and disease, and contributing to overall lower fluid costs. Today, we will discuss selection, in-use management, recycling and disposal of metal removal fluids.
Our interviewee today has had extensive and wide-ranging experience within this field, including the development of industrial lubricant specifications, best fluid management practices, and recycling and disposal of oily water and used oil.
Don Smolenski, a PhD in Chemical Engineering, has been recognized for his work in the field. He is the co-inventor of the GM Engine Oil Life Sensor, now installed in nearly all GM vehicles. He is also experienced in engine test development. He has been the chair of GM’s LS2 Committee for 18 years, which has generated one of the most comprehensive industrial lubrication standards in the industry. Dr. Smolenski also drove the safe use of recycled oils in plant applications. As a result, GM now uses more than fifty percent recycled oils in its North American plants. He holds several patents and has numerous publications to his name. He has also been very active in professional societies including the STLE, the Engineering Society of Detroit, and the Society of Automotive Engineers. He is currently a Technical Fellow in General Motors’ Research and Development Center. Today, we will get an inside look into his work and examine the metalworking fluid management field.
KARA: Don, welcome to the STLE Compass.
DON: Thank you.
KARA: It’s really great to have you. So Don, can you talk a little bit about metalworking fluid management and what it focuses on?
DON: Sure. First off, when we talk about metalworking, that comprises both metal forming operations such as stamping and drawing and those kinds of things as well as metal removal fluids you know, drilling, tapping, broaching, grinding and all those kind of chip-making processes. Both have similar challenges, but I’ll probably restrict my remarks primarily on the metal removal fluids. For other industrial fluids like hydraulic fluids, we, I think, are confident we can define them reasonably completely with specs, you know bench and rig tests, physical and chemical properties and they’re all fairly readily managed in-use by just keeping them clean, cool and dry. Now metal removing fluids on the other hand, pose a little more of a challenge, for several reasons. One, due to the great variety of different materials working in the machine: aluminum, cast iron, stainless steel, maybe even bronze and things like that. We’ve got a lot of different processes with slightly different appetites: milling, drilling, tapping, reaming, grinding, broaching, gear hobbing, the whole deal.
KARA: Wow.
DON: And also various process parameters, you know, we’re going to adjust feed speeds, depth of cut and we’re going to have different required surface finish and dimension requirements and so on. So compared to hydraulic fluids, metal removing fluids, in particular aqueous fluids, can be a heck of a lot more difficult to manage in-use as well due to concentration and pH variation, the need to manage those very carefully and also, you’re going to always have contamination by other process fluids, cleaners and tramp oils, typically hydraulic fluids and weight lubes, your dirt and metal fines and of course, because they’re aqueous, you have bacteria and fungi, the possibility of those growing.
KARA: Okay. So given all of these different areas and different things that you can do within the field, what sort of applications would it have, or where would it apply?
DON: I think that virtually any industry that deals with metals somewhere along the line has some machining and forming operations. The ma and pa shops that make small parts, to large automotive plants, huge earthmoving equipment manufacturing, and even aerospace, somewhere along the line there are some metal forming and metal removal operations. Whether or not it’s at the end-user or somewhere in between, there’s some of it going on somewhere.
KARA: Given the large impact, that it impacts a large amount of industries, what are some issues in the field or some topics that those in the field are researching?
DON: I think my top three issues would be health and safety, environmental and cost. These all continue to be at the forefront. For health and safety, reduced worker exposure through reduced machining fluid mist levels, the use of lower misting fluids, and guarding and ventilation, that kind of thing will continue to be a challenge. We’re also interested in more “worker friendly” formulations, both in their new, pristine condition and certainly over the life of the fluid. High microbial counts in aqueous fluids have been associated in the past with Hypersensitivity Pneumonitis or HP which is an allergic lung reaction, and we believe that maintaining low bacterial and fungal counts is desirable, and a way to stay away from HP. At GM, we’ve got a document that defines, in great detail, how we manage the fluids and that’s been of huge interest to the UAW, for instance, and has actually been discussed regularly in union negotiations.
An example of the second item, the environmental issue is the phase out of chlorinated paraffins, which are really, very cost-effective, very effective extreme pressure additives for heavy duty machining operations. Now Canada is already pushing to have them phased out, and we’ve also been on notice that the U.S. EPA is looking hard at them as well. Now, alternatives are being evaluated, but they’ve got to be not only machined as well, but certainly as an end-user, we’re looking for them to be fairly cost neutral, or no unreasonable cost penalty. When you deal with the used oil side, like I have in the past, you well understand the environmental concern when the cost, if you dispose of, say a seven percent chlorinated broaching oil, for instance, is going to be several fold that of a non-chlorinated product. With low levels of chlorine, you can, you know the solution can be diluted, but in this case, it’s just not going to happen. And here there’s also an overlap between environmental and health and safety. In this case, some of the chlorinated paraffins have been classified as suspected human carcinogens, depending on chain length and degree of chlorination and all that sort of thing and I think this raises some concern about this general class of additives.
KARA: Sure.
DON: You start cutting pretty finely, it’s a lot grey around that and it doesn’t give you a warm and fuzzy.
KARA: Probably not.
DON: Now the third item, the cost of the fluid, is something we have to look at not just the purchase cost, purchasing looks at cost per gallon, but we really have to look at the life cycle cost and that’s going to continue to be of paramount importance to be competitive. A fighting grade soluble oil might be pretty cheap to purchase, but if you have to use a higher in-use concentration, you have to do continuous tankside additives, particularly of biocides, and you have to do a drain, clean, and recharge on a regular basis, that’s going to change your economics. A significantly more expensive biostable fluid might actually cost less on an annual basis, if you’ve properly taken all of these costs into account. And then the other part of this is the life of the machine tools, which can obviously, drastically be affected by the quality and condition of the fluid. Here again, a better fluid can bring you some big tool life savings. Sometimes this can be difficult for our plants to resolve, however, because the tool folks are a different cost center than the fluid folks, which is unfortunate.
One additional comment about tool life too, often it’s set at some fixed interval and what happens is we bring in a better fluid, and we don’t take advantage of it because no one ever changed the interval, they never went to the pilot and asked how much longer can we extend this? So that’s one of those things that doesn’t come for free if you don’t let that interval be extended.
KARA: You were just talking about this, the cost of the fluid, and considering that cost issue for different types of fluids, what would you recommend for those trying to choose one?
DON: We look at several things in our product selection at GM. We try to centralize a little bit so we get some control. The very first thing has to be a very thorough tox review of a full disclosure Material Safety Data Sheet (MSDS). And this is really a global call. If it’s going to pose an unreasonable risk to our workers anywhere in the world, that’s going to be a no. Second would be the review of the plant machining history. Basically, has this product been used somewhere else to machine a similar process and does it have good performance? Third is the submission of data against any plant or corporate physical, chemical and performance tests, or LS2 standards. Both to say that we have some bench test and we also know what the fingerprint of this fluid is. Fourth, if it’s an aqueous fluid, we want it to be biostable and some proof of that in terms of both a lab test and some sixteen week plant data. And also, the next thing would be fluid VOCs and their potential impact on the plant air permit and that’s going to be very much plant specific. So, you know, if it’s approved in one plant, it doesn’t necessarily allow it to come into another plant if their VOCs are bolstered to their allowable permit level. And finally, waste treatment. We can’t forget those guys. They have to be able to handle a system dump and we can look at some typical types of waste treatment parameters such as biological or chemical oxygen demand but at the end of the day those guys are going to say, “Give me a quart of that, let me take it down and see if I can break it.”
Also, the best time to change an aqueous fluid is something that is still not well understood. You don’t want to change it too early and waste the resource, but you don’t want to limp along with high maintenance costs either. It seems like we should be smart enough to construct an economic model to tell you where the cut point is.
KARA: Okay. So what would you say the overall impact to GM would be, just of this general field? Just as we’ve been talking, I just thought of this, but what do you think about that?
DON: Certainly, it is something, like I said, we’ve tried to manage it at a central level to say, if we’re machining valve transmissions, valve bodies in Saint Catherines, Ontario, and Toledo, Ohio, and Ramos Arizpe, Mexico, why aren’t we using the same fluid? It’ll make it easier for us to troubleshoot. If we’ve identified the best fluid, we should be using it everywhere, we can start to deal with volumes and we have less environmental issues and personnel issues to deal with, when you have a smaller number of fluids. We are trying to get to a point where we do a much better job looking at overall system cost and not just the cost of the fluid versus the cost of the machine tool or the cost to waste treat, all separate cost centers, nobody talking.
KARA: That makes sense. You want to have an overall idea of exactly how much this is going to cost versus another option. That definitely does make sense. So have there been any major developments or changes that you’ve heard about in the field?
DON: I think this field is being shaken up a little bit lately. You know, it’s kind of a stodgy, old field, but there’s a lot of stuff going on. As far as a few major developments, I can think of two that are really relevant to us. The first is the development of biostable fluids. By virtually eliminating the use of tankside biocides while still maintaining very low bacterial and fungal counts, these fluids have resulted in a cleaner, healthier environment for our workers. You know, we’re not seeing ten to the seventh, ten to the sixth bacteria. We’re not seeing myco, we’re not seeing fungus. And we’re well into implementation in many machining plants. That’s the rule, rather than the exception in GM. That’s the direction we’ve gone because we think it’s certainly healthier for our workers, and more cost effective.
The second big development, I think, is still more in its infancy, and that is minimum quantity lubrication or MQL machining. In this case, instead of having these large, high flow sumps, and we have at least a few sumps over 100,000 gallons, that’s a heck of a lot to maintain, and the high fluid delivery rate in terms of gallons per second; in MQL, which uses a carefully targeted minimal amount of fluid, you might be talking ounces per hour, so you’re going to get away with dealing with a whole heck of a lot of fluid. There has certainly been proof of concept of this and implementation in some plants but there are at least a couple major roadblocks. The first is a cultural change. You have to convince your machining people that this is going to work, and it’s going to give you the surface finish, the dimensional tolerances and also good tool life. The second is more of an infrastructure issue. It’s one of the key, but somewhat unspoken functions of coolants, is to move chips and with MQL, you’re going to have to install some other types of chip handling equipment. There are systems out there, but it might make the cost of a retrofit to any existing system just not cost competitive. The best opportunity for MQL would be in new installations. If you’re talking about dry machining, these same comments would apply as well.
A couple other things to consider: certainly the use of vegetable oils or esters, renewable coolants, and multifunctional fluids, where the fluid concentrate is used undiluted in the hydraulic systems, for instance.
KARA: Okay. So, in general, what would you say are the conclusions or concepts that listeners should take away from today’s discussion? What is the future of the field?
DON: Well, as far as the future as an end-user, we’re going to have to machine faster, smarter, cleaner and cheaper, and especially cheaper. That’s spoken like a true fluid end user. We always want a cost reduction. But faster allows more throughput and a better return on that capital cost of the machine tool. That’s an asset that we have to get the most money, the most productivity out of.
KARA: Definitely.
DON: Smarter means breaking down silos and doing what’s best for the overall system, sometimes forcing some compromising among fluid cost, maintenance cost, tool cost, waste treatment cost, all the while doing the best possible job to protect the health of our workers, machine most efficiently and cost effectively with the least impact on the environment. Now, cleaner means reducing airborne mist or coolant splash for continuously improved worker health and safety, reduced housekeeping too. Cheaper means less system life cycle cost. Again, I keep hammering on that, but I don’t see machining going away any time in the near future.
My closing advice is to engage all of the stakeholders when you set up a machining operation, including product quality, who is probably your ultimate customer, purchasing, machine tool, maintenance, waste treat, on-site chemical manager, and so on. And discuss and review all the costs, constraints and goals, and agree that you’re all going to support a common path forward, so you don’t have people you know, pointing in different directions. And also, be prepared for change because not continuously improving is not an option if you want to stay competitive in this industry.
KARA: Isn’t that always the case? I always take the lesson that you should learn something new every day. So, that’s kind of similar, but you should always improve.
DON: You’d be forced to.
KARA: Well, thank you Dr. Smolenski for joining us today and for your insight. I’m Kara Lemar. For more news and information on metalworking fluid management you can visit our website at www.stle.org. If you are interested in learning more, you can also take the Metalworking Fluid Management course in November that will be held at the Engineering Society of Detroit’s facility in Southfield, Michigan. Thank you for joining us today. This has been another episode of The STLE Compass, pointing you in the right direction.