Page 36 - MetalForming-Oct-2018-issue
P. 36
Lubrication Challenges
Booth A1419
Fig. 3—Aluminum alloys that formerly were used only in aerospace applications are finding their way into automobile manufacturing. ©Can Stock Photo/Leaf
technologies build in better detergency (prevention of particle agglomeration and coating formation on surfaces), dispersion and wetting, all needed for the lighter metals.”
Some operations still require straight oil metalworking fluids (MWFs), says Mark Soder, Houghton’s director of technical service, research and tech- nology. Smaller parts and those requir- ing tight tolerances or a smooth surface finish are examples of this. Magnesium work often uses neat oil because it requires a lubricant that will not stain or release hydrogen gas. However, even
here the trend is toward water-soluble fluids, for insurance reasons. Emul- sion-based fluids are less flammable than neat oils and you do not have to evacuate the mist like you do with oils, he says.
High Temperatures, High Pressures
High-speed machining fluids for working with softer metals must have good cooling and lubricating properties to prevent excessive heat formation due to friction. Softer metals can expand and lose strength if the tem- perature rises too high. However, many of the new high-strength alloys must be heated to make them ductile enough to work with.
Aluminum alloys that were previ- ously only used in the aerospace indus- try are beginning to be used in the auto- motive industry, McClure says (Fig. 3). The 6000- and 7000-series alloys, formed at elevated temperatures—500 to 750 F)—don’t always require a lubri- cant. When they do, the lubricant may include more solids, inorganics and phosphates. (More on no-lubricant scenarios later.)
Lubricants for the automotive industry have to perform at higher temperatures and pressures, McClure says, while maintaining compatibility with adhesives, cleaners, primers and welding. Straight oils don’t encounter the biological or hard-water problems that water-based fluids do, he adds, but they often become volatile at higher temperatures, producing fumes and smoke, and they may be prone to oxidation.
Oxidized lubricants are harder to clean off of parts, McClure adds. Lubri- cants and other fluids must not inter- fere with adhesives, including struc- tural adhesives, which are seeing increasing use as a replacement for welding. This is an important research area, McClure says (see Adhesives).
Dave Slinkman, senior vice presi- dent, global research and technology for Houghton, notes that rolling HSS or aluminum sheet requires greater force, but at the same time body panels
Adhesives
HSS and aluminum parts are more difficult to weld than mild steel. Epoxy structural adhesives are sometimes used in addition to or instead of weld- ing in situations where welding is dif- ficult.
Epoxies are good sound deadeners and sealers, and they increase struc- tural rigidity.
2015 automobiles typically had about 55 linear ft. of structural adhe- sives. 2017 models have about 68 lin- ear ft., and this is predicted to increase to 87 linear ft. by 2020.
Some high-end, aluminum-inten- sive vehicles contain as much as 600 linear ft. of structural adhesives.
Source: Ted McClure, Sea-Land Chemical Co.
34 MetalForming/October 2018
www.metalformingmagazine.com
