Lightweighting – New Challenges for Metal Forming Lubricants

Sustainability is a core value for FUCHS and for many of our customers. Operating more sustainably often means turning to new processes, materials, and technologies that can support these goals. New government regulations around fuel efficiency have led automakers to do just this. Strategies proposed to achieve fuel efficiency have included aerodynamic designs to reduce air drag, improved power train technologies, electric mobility, aluminum castings, and reductions in vehicle weight - known as “lightweighting.”

Lightweighting has led to significant changes in the metal that is used in structural, seating, and body components. To date, lighter weight advanced high-strength steel (AHSS) has led to the most significant changes in weight, but new aluminum alloys are also being introduced, especially for use in body panels and closures. Lighter and stronger metals can increase vehicle safety and improve fuel efficiency, but these metals have changed the dynamics of forming parts. The materials can create more friction and can be more difficult to form.

Lubricants play a critical role in the successful forming of metal in stamping presses. These lubricants also have far reaching effects to post processes, such as anti-corrosion protection, welding, cleaning, painting, and housekeeping. The new metals used in lightweighting vehicles have properties and undergo processes that can affect the performance of metal forming lubricants. Lubricants used in traditional cold forming may not provide the properties necessary to form the new metals. Companies that stamp AHSS or aluminum should become aware of these changes and their effect on lubricant performance. FUCHS has developed new lubricants that meet the demands of AHSS and aluminum forming and improve overall performance.

Advanced High Strength Steel

Most AHSS provide added strength to the material at a lighter weight than mild steel. Typically, these materials work-harden, that is, the strength of the material increases as the material is deformed. As these materials are used in structural components and in the passenger cradle of vehicles, the work-hardening feature helps to protect passengers in the event of a crash. However, the very act of stamping or forming parts from blanks requires substantial deformation of the material. In effect, work-hardening occurs during the act of stamping and increases the hardness of the steel.

Hardened steel reduces ductility and creates more friction in the dies. Metal forming lubricants that were effective in forming mild steel, may not perform as well when parts are made from AHSS. Historically, water-based synthetic lubricants have been the lubricant of choice for forming steel. Unfortunately, these lubricants lack film strength and generally cannot contain high levels of extreme pressure (EP) additives. Without these characteristics, lubricants can lose viscosity and general stability as the work hardening and the resulting friction occurs.

Fortunately, FUCHS has done substantial development work to make products that perform well when forming high-strength and advanced high-strength steels. By incorporating heat-resistant additives and devising new methods to increase EP additives in water-based lubricants, new technology synthetic lubricants can perform better on high-strength steel (HSS). Other types of lubricants have been found to perform even better on these steels. Oily emulsions with chlorinated paraffin have been available for many years. This technology performs very well in forming the hardest steels in the most complex stampings. But this technology can be difficult to clean from parts and chlorine has been prohibited in some areas. FUCHS offers sustainable, chlorine-free oily emulsions with comparable performance. These new chemistries may cost more per gallon than older technology lubricants; however, the wrong choice in lubricant when working with HSLA steel, HSS, and AHSS can create costly damage to dies and can lead to part quality issues.

Aluminum

HSLA Steel, HSS, and AHSS have become important materials that help automotive OEMs reduce vehicle weight and increase fuel efficiency and vehicle safety. These materials are primarily used to form structural components. Work is underway to replace steel altogether with aluminum, primarily in body in white (BIW) panels and closures. Aluminum can provide 60% weight savings compared even to the lightest high-strength steel. However, aluminum has poor stretch and elongation properties, and as a result can be very difficult to form. As OEMs look to make complex body parts from aluminum, lubrication becomes critical to successful forming.

Lubricants used to form automotive BIW parts and closures usually require strict adherence to OEM approval testing. Compatibility with aluminum may have been required, but the focus of these approvals and the lubricant suppliers’ formulas was primarily based on the predominant material – steel. Aluminum has characteristics different from steel that can affect a lubricant’s performance. As the use of aluminum in stampings increases it is important to review these differences and to consider that a lubricant designed for use on steel may not be the best choice for forming aluminum.

The requirements for lubricants used to form aluminum parts can be unique. These lubricants need polar additives to help the lubricant adhere to aluminum’s smoother surfaces. EP additives are not effective on aluminum, so boundary additives provide better lubricity. The lubricant should have a lighter viscosity to prevent blanks from sticking together. Also, it is critical that the lubricant residue on parts does not adversely affect adhesive bonding.

Your Expert in Metal Forming Lubricants

FUCHS is the leading supplier of lubricants for metal forming. We work with OEMs, Tier stampers, and industry consortiums to develop new technologies to optimize performance with new and higher strength metals and new processes. During our years of experience, FUCHS has developed a comprehensive line of products for all metal forming needs. Our team of field engineers, R&D staff, and technical service personnel can provide professional support for your metal forming needs in any of the following: