TLT: How did you become involved in the metalworking industry, and what lessons have you learned?
McClure: My involvement in the metalworking industry was not planned, but it happened through a series of connections, which helped shape my career as much as anything done intentionally. I was trained as a synthetic organic chemist, plant physiologist and ecologist. While in school, I did not know what a metalworking fluid was or the meaning of tribology. I needed employment while finishing my research, taking a position at DuBois Chemical, in their industrial metal-finishing product development area, where I also first connected with a Sea-Land Chemical representative.

After about a year, the manager of the lubricant laboratory, who became my early career mentor, requested I be transferred to his department where I worked on transportation, industrial and metalworking lubricants and was introduced to STLE. My mentor then took a technical director position in the Cleveland, Ohio, area, where I had grown up. A product development chemist job subsequently became available there, which was offered to me. This was an exciting possibility to reconnect with and learn from someone I had a great deal of respect for, and to move closer to my family. 

Historically, chlorinated paraffins were critical ingredients in metalworking fluids (MWFs) for severe applications and were constantly being scrutinized by regulators, as is still the case. As a result, R&D labs were focused on chlorinated paraffin replacements and replacement strategies. In the 1980s, supporting a large customer’s quality program, my entire product development staff was trained in statistical design of experiments (DOE), a practice I have used since then, and is currently gaining popularity in MWF development programs.

In the early 1990s, professor John A. Schey, at the University of Waterloo, organized a two-year group project, including North American steel, auto and lubricant companies, to investigate the tribology of forming galvanized steels gaining popularity in North America to improve automobile corrosion protection. Schey was widely recognized as a preeminent metalworking tribologist since the publication of his landmark book, Tribology in Metalworking: Friction, Lubrication, and Wear, in 1983. Serving on the steering committee of the group project, I connected with Schey regarding chlorinated paraffin replacement testing strategies, and one of his graduate students working on the project, Gregory Dalton, who years later became my business partner in the consulting business.

Schey recommended two tests be used to evaluate lubricants to replace chlorinated materials: the draw bead simulator, designed by Dr. Harmon Nine at General Motors, and the standard friction test for metalforming lubricants in the auto industry, and the twist compression test (TCT). The draw bead simulator operates in the hydrodynamic and mixed-film lubricating regimes. It is a simulation test that correlates well with production experience in automotive stamping where draw beads are used to control metal flow. The TCT, a bench test, evaluates boundary-EP performance, critical in chlorinated paraffin replacement, with test results corresponding closely with field experience, ranking EP lubricants in preventing adhesion or galling. Schey told me this parallel between lab and field was due to the TCT creating a lubricant starvation condition: the same condition existing in severe metalworking operations in locations where adhesive failure is most likely to occur. Using these two instruments, one can quickly characterize and compare the performance of metalforming lubricants across a range of conditions.



I feel strongly that one should not only know one’s business well but also go outside this relative comfort zone and get to know your customer’s business. Lubricant development chemists who visit end-user plants, viewing production and speaking with operators and engineers, are more likely to develop effective products. In my career, I worked closely with engineers and materials scientists at OEMs on lubricant approvals. In addition to STLE, I also attended NADDRG meetings with many of the same automotive and steel scientists. This was important when Dalton, Schey’s former graduate student, and I consulted for the AutoSteel Partnership for eight years: part of the team studying the tribology of forming advanced high-strength steels, an enabling technology for automotive lightweighting.

Throughout my career, I worked with many technically knowledgeable and helpful additive and base stock suppliers, including Sea-Land Chemical. After consulting, I connected with Sea-Land Chemical, where I am currently employed.

Over the years one makes many connections. These are in constant flux. Coworkers become competitors, who become suppliers, who might become customers or collaborators.

TLT: Can you describe the evolution of metals you have seen used in metalworking applications over the past 30 years?
McClure: Much of the metal worked goes into automobiles. Before the 1990s, there were significant issues with automobile longevity due to the body structure corrosion. Some imports used zinc-coated steels, and in the early 1990s, U.S. auto companies began incorporating galvanized steels into automobiles in order to improve corrosion resistance. Three main types of galvanized sheet steels are commonly used in automobiles: hot dipped and electrogalvanized, and galvannealed steels. The hot dipped and electrogalvanized materials have a 100% soft-zinc surface, while the galvanneal is coated with zinc and then annealed, producing a hard-zinc alloy coating containing about 9%-12% iron. The zinciron alloy is easier to weld, resists scratching and accepts paint better than the purezinc coated surfaces.

OEMs, and later the AutoSteel Partnership, developed testing protocols including corrosion, stain, cleanability, paint compatibility and coefficient of friction for lubricants to be used with these and the other body structure materials. Stamping lubricants and mill oils evolved to meet the requirements of these tests. Compared with bare steels, early electrogalvanized steels varied widely in frictional performance, not ideal for a robust manufacturing process. This variability was found to be due to the orientation of zinc crystals on the surface, and subsequently resolved. Hot dipped galvanized generally gives consistent frictional performance, but wetting is more difficult for water-based lubricants than with electrogalvanized or galvanneal. The brittle galvanneal coatings are more prone to powdering during fabrication than pure zinc and can build up on tools. Metalforming lubricants were adapted to perform well with each of these zinc-coated steels.

More recently, the drivers in automobile material evolution have been environmental and productivity demands. Lightweighting, to meet corporate average fuel economy requirements, is ongoing. This has led to dramatic changes in what automobiles are made from and how they are made. Automakers have moved to thinner gauges of high strength steels (HSS) and then advanced high strength steels (AHSS) to improve fuel economy while maintaining crashworthiness. According to Ducker Worldwide, the average mild steel content of auto body structures in 2007 was over 50%, moving to less than 30% by 2015. Mild steel grades used in auto bodies commonly have tensile strengths of 250-300 MPa, and now there are steels used approaching 2,000 MPa. Generally, as steel strength increases the ductility decreases, making the forming of complex parts challenging. The Gen 3 steels currently being developed address this limitation with targets around 1,200 MPa tensile strength with elongation over 20%.

Manufacturing techniques have evolved along with the materials to optimize weight reduction, including the use of hydroformed tubular frame structures, tailor welded blanks and tubes and warm and hot forming. High strength steels challenge the durability of presses and tooling. New, improved tooling materials and coatings have been developed, and highly controlled servo presses are becoming more common. The changes in the processes, tooling and workpiece materials are dictating changes in lubricants. Stamping die temperatures can reach 100-200 C, making lubricant low volatility and oxidative stability more important. Also, the lubricant must perform well at these temperatures and at much higher contact pressures. The highest strength steels currently are the press hardened steels. These are austenized at over 850 C, formed, then cooled at a rate of >50 C per second to harden.

Other lightweight materials also are used in auto body structures including magnesium and aluminum. Aluminum has been used for years in large body parts with low ductility requirements like hoods. The use of aluminum has increased steadily but remains low compared with steels. Ducker Worldwide estimated aluminum content per light vehicle increased by a factor of 2.4 between 1990 and 2015. Although the density of aluminum is less than half that of steels, some factors holding aluminum use back have been springback, limited ductility, joining difficulties and cost. It is interesting that many AHSS have shown some of these same limitations. Use of higher strength aluminum alloys is increasing, including 6000 and 7000 series materials, historically used in aerospace applications. Lubricants are being designed to facilitate forming of aluminum alloys, including solid and semisolid coatings. Warm forming of high strength aluminum alloys, often over 300 C, is used to improve formability significantly. This requires the use of specialized forming lubricants, many containing solid lubricants, which can withstand these temperatures.

Aluminum machining also is increasing. Many cast aluminum alloys contain some magnesium, which can put a lot of pressure on coolant cation stability and shorten sump life significantly. Low foaming, long-life fluids designed for aluminum and multi-metal machining are being developed as a result. Lightweighting also is taking place in aerospace. Composite use is increasing, mostly replacing aluminum, while the titanium content of airframes is increasing because of its high strength-to-weight ratio compared with alternative materials. Titanium is a very poor conductor of heat and has a strong tendency to adhere to tools, which presents challenges to the MWF formulator.

TLT: What projects are you currently working on?
McClure: Most of my work presently involves friction testing using twist compression tests. With rapid changes in materials and processes in industry, TCT is very useful. One can easily test many workpiece and tool materials and lubricant combinations under various pressures. This has been the focus of my work in recent years.

When regulators suggested they would ban the manufacture and import of all medium- and long-chain chlorinated paraffins beginning in May 2016, industry was tasked with identifying critical uses where it would not be practical to replace these materials. I did some work on several alloys following this and identified that chlorine replacement in lubricants for severe applications, particularly forming, with austenitic stainless steels, including the most common, SAE 304, would be very difficult with conventional chlorine replacement packages currently in use. Projects were done using one factor at a time, binary and ternary DOE additive experiments to identify effective combinations. This work is ongoing today as new lubricating additives become available.

A similar approach is being taken regarding lubricants for aluminum alloys, considering the increased usage of new and existing alloys in the automotive industry. Several polar lubricating additives were screened using TCT tests on soft and hard aluminum alloys. Also included are EP additives known to perform well on steel to address the increasing need for lubricants used to machine multi-metal components. Test results with aluminum do not correlate well with results on steels, so combinations are being investigated for these applications.

TLT: What trends and challenges do you see for the future of MWF additives?
McClure: Considering regulatory activities, trends in manufacturing and the likely responses by the MWF manufacturers provide some ideas regarding the possible future direction of additive development. These factors, along with global competition, consolidation at all levels of supply chains and evolving technologies also should be considered.

Typically, when information regarding adverse safety or environmental impact of a particular additive chemistry became available, MWF users and manufacturers have responded much more quickly than the regulations changed. Recently, considering GHS, REACH, TSCA reform and registrations worldwide, MWF formulators and additive manufacturers are having to react to the regulations. GHS and global inventories have become more significant considerations for MWF formulators and additive manufacturers. As these companies as well as MWF end-users continue to be consolidated, the need for producing and using globally registered additives increases. This reduces the pool of additives available to formulators.

Specifically, the number of biocides available has decreased, and this will likely continue due to the high cost of maintaining registrations. This makes it more challenging to meet the needs of our dynamic manufacturing environment. Global competition in manufacturing dictates the need for increased productivity. Long-life fluids, particularly those used for machining magnesium containing aluminum alloys, are required to help minimize downtime. As a result, cation tolerant additives for fluids are becoming more important. High production rates require high speed and fluid pressures, increasing the need for low-foam additives. Multifunctional additives also might enable formulation of more cost-efficient MWFs.

The use of environmentally friendly chemistries in MWFs is increasing but not at the rate that some expected, possibly due to the perceived cost increase and global competitive environment. Increased social awareness of the benefits of sustainability and the cost of climate change should drive changes in MWFs and MWF management practices in the future. Automobile manufacturer associations will likely encourage this.

The German automobile industry association, VDA, has published recommendations for guiding principles in the automotive industry for improving sustainability in the supply chain and have developed a sustainability questionnaire that is being introduced at suppliers and sub-suppliers. SAE now publishes the SAE International Journal of Sustainable Transportation, Energy, Environment, & Policy. Based on this trend, I expect the use of sustainable raw materials to increase in MWFs into the future. Life cycle analysis is a central tool for assessing sustainability. If cradle-to-cradle models are used more, this will encourage MWF users to develop closed-loop recycling programs that fluids will have to be compatible with. If electrified autonomous vehicle networks become common, fewer, more reliable automobiles will be required, reducing the need for MWFs, particularly metal-removal fluids. This potentially could remove some of the pressures on productivity and MWF cost.

You can reach Ted McClure at ted.mcclure@sealandchem.com.