Page 40 - MetalForming-Oct-2018-issue

Lubrication Challenges
ical operation,” he says, “you might use a fluid that’s specific to one type of material in a particular type of operation.”
A new lubricant must be approved for use before an OEM introduces it onto the fac- tory floor, where making changes involves a long process, McClure says. Changes in the factory tend to be incre- mental to prevent issues in the manufacturing process. For example, fluids must be com- patible not only with work- pieces (which can have various surface treatments, including the galvanized coatings on HSS), but also perform well with the various tool materials and die coatings with which they come into contact (see Fig. 4).
Environmental
Considerations
Environmental considerations affect fluid formulations as well. Carmody sees a trend toward “minimum quantity lubrication” and away from “flood lubrication.” This approach typically requires a change in manufacturing equipment as well as different fluid formulations, she says, so operations generally do not adopt this approach until they are ready to replace their equipment.
Dry machining has proven success- ful in numerous operations, but MWFs
Does one size fit all? ‘It’s always a balancing act.’
still are required for applications that require cooling and lubrication, includ- ing titanium milling for aerospace applications or working with compact- ed graphite iron for engine parts. Using an MWF reduces tool wear (thus reduc- ing tool replacement and disposal costs), and produces better parts by
Aluminum, magnesium and their alloys are prone to staining.
reducing residual stresses and dimen- sional errors, and improving surface finish. Fluids also allow processes to run at faster speeds without building up excessive heat. These factors can more than balance out the environ- mental impact of using fluids in the process.
Environmental considerations also affect what additives are used. For example, McClure says, conventional EP additives, including sulfurized, chlo- rinated and phosphorus-bearing addi- tives, can react with steel but not nec- essarily with nonferrous metals, zinc-coated steels and tool coatings. OEM plants have gotten away from chlorine, he adds, but it is difficult to replace chlorinated fluids in some severe operations, including fineblank- ing. Also difficult, he says, is replacing chlorine for severe operations on some stainless steels as well.
Regulatory requirements differ from one region to another, says Slinkman. Older fluids, including those that contain chlorinated paraf- fin, may be acceptable in one region, but fluid suppliers in other regions may have to make significant changes to their products. Products for sale in Europe must comply with the Reg- istration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulations.
“We have to conduct a complete review of our product lines to make sure that we are compliant,” Slinkman says. “We expect this to have a huge impact on the industry in terms of what products are available for these new uses.”
Often an old fluid that works well in one region of the world is heavily reformulated for sale in another region, Slinkman continues. “That’s a big change from what we’ve seen.” To keep
Fig. 4—Houghton chemist Scott Lay inspects an AHSS cup made with the state-of-the-art Valley Forge Labs 40-ton stamping press that the company uses to eval- uate new technologies. (Figure courtesy of Houghton International)
MWF is mainly a coolant, especially to keep the chips from igniting (see Mag- nesium 101).
Some aluminum-forming opera- tions use semi-solid, half-hard lubri- cants, McClure says. Semi-solid or solid lubricants overcome some problems because they stay put rather than migrate within a coil, preserving an even coating, and they can provide excellent lubricity.
However, these coatings can be cost- lier to apply and, like traditional fluids, must be compatible with assembly, cleaning and painting.
Adaptability Issues
Some fluid formulations advertised as multipurpose and suitable for a wide range of metals and applications may not live up to the one-size-fits- all claim. “It’s always a balancing act,” McClure says. You can optimize your formulation for one type of metal or one operation, but “users are reluctant to inventory too many different fluids in the plant.” Thus, it’s a trade-off between simplifying inventory and optimizing performance. “If it’s a crit-
38 MetalForming/October 2018
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