This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Tribological Factors Affecting the LDH Test
Annotation ability available
Sector:
Language:
English
Abstract
The present work is aimed at investigating the tribological factors influencing the LDH test. The material used was AKDQ cold-rolled bare steel, 0.82mm thick. The investigated factors included: test speed (0.833, 4.167, 6.667, and 8.333 mm/s), lubricant viscosity (4.5, 7.0, and 12.5 mm2/s), punch roughness (0.033 and 0.144 μm Ra), and test temperature (25 and 50 °C). Test speed and lubricant viscosity form a variation of the numerator of the Stribeck curve's x-axis (ηV). With ηV increasing from 4 to 120 mm3/s2 friction decreased, resulting in a 0.5 mm higher LDH. Increasing the punch roughness decreased friction producing an increase of 0.25 mm in the LDH. There appears to be an optimum roughness -- at which the roughness features act as lubricant reservoirs but the asperities do not break through the lubricant film -- resulting in minimum friction, therefore, maximum LDH. Beyond the effect test temperature has on the lubricant (which was accounted for in the lubricant viscosity), test temperature affected the material's formability: increasing the test temperature reduced the LDH by approximately 1.00 mm. The reasons for this effect are not known at present time.
Citation
Fischer, R. and Schey, J., "Tribological Factors Affecting the LDH Test," SAE Technical Paper 920434, 1992, https://doi.org/10.4271/920434.Also In
References
- NADDRG “Recommended Referee Practice for the LDH Test” Oct 1987
- Schey J.A. “Tribology in Metal Working: Friction, Lubrication and Wear” ASM 1983 60 79 520 524
- Lindsay J.H. Nine H.D. Mickalich M.K. “The Effect of Surface Finish on the Drawing Characteristics of Chromium Plated Sheet Metal Forming Tools” SAE Paper 910510 Autobody Stamping Technology Progress SAE SP-865 15 27
- Izworski N. Graf A. “Obtaining LDH Stability” SAE Paper 910512 Autobody Stamping Technology Progress SAE SP-865 41 45
- Mulitze W. Project Report Aug 1989