New, lightweight materials are at the center of the global drive for improved vehicle fuel economy. These new materials require new manufacturing techniques, creating a challenge and an opportunity for lubricant manufacturers.
During Afton Chemical’s Key Driver Seminar in May 2015, Dr. Taylan Altan, Director of the Center for Precision Forming at The Ohio State University, presented the following information on current industry initiatives and new test methods for selecting lubricants in the future.
The automotive industry is increasingly emphasizing the use of lightweight materials in stamping, such as Advanced High Strength Steels (AHSS), Aluminum alloys, and carbon fiber composites. This trend presents new challenges and oppor- tunities for suppliers of stamping lubricants and additives. The use of these materials requires not only detailed infor- mation about material properties but also new lubricant systems that are appropriate for forming them.
In selecting lightweight materials, the automotive de- signers, must consider several important factors including regulations, fuel consumption, pollution, customer satisfac- tion, crush resistance, and materials and processing costs.
New high-strength and lightweight materials, used exten- sively today in forming and stamping, include Advanced High Strength Steels (AHSS) and various Aluminum alloys. These materials are formed “cold,” i.e. initially at room tem- perature or at elevated temperatures; for example, special steels are formed at 900 degrees Celsius and high-strength aluminum (Al) alloys (2000 and 7000 series) are formed at about 400 degrees Celsius. During stamping, depending upon the material and forming conditions, relatively large pressures and temperatures are developed at the sheet material interface.
During forming, the mechanical energy used for deforma- tion is transformed into heat and temperature increase at the sheet/die interface. As a result the lubrication condi- tions are affected. For example, in deep drawing of a round cup, a relatively simple operation, temperatures of about 80 degrees Celsius are generated, due to plastic deformation and friction, when forming an AHSS, DP590 at moderate forming speeds. In practical production operations, the temperature of the tools increases to reach 200 to 300 degrees Celsius, depending on material and strok- ing rate (strokes per minute) used in the process. Therefore, requirements on stamping lubricants, and needed additives, increase with increasing use of high-strength, low-weight materials.