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Industrial Implementation of Practices for LDH Stability
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English
Abstract
The LDH (Limiting Dome Height Test) is widely used at Ford Motor Co. stamping plants laboratories to monitor the formability of incoming sheet materials. Although the LDH test is very easy to implement and interpret, variability of the results and poor reproducibility between laboratories limit its acceptance. In this investigation, some of the causes of variability and differences between plant laboratories are discussed. Much of the experimental work was done at plant laboratories and the results are directly applicable to quality control (QC) machines.
It was found that the binder force and the binder shape have a big influence on the results, and they should be carefully controlled. The binder cleaning procedure is also relevant to the test variability. Punch temperature has a much greater influence on QC machines than on research machines and a method for controlling the punch temperature in QC machines is presented. Finally, the influence of prior samples’ material on the LDH value of a reference material is discussed.
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Citation
Graf, A. and Izworski, N., "Industrial Implementation of Practices for LDH Stability," SAE Technical Paper 930816, 1993, https://doi.org/10.4271/930816.Also In
References
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- Fisher R. F. private communication July 1992
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- “The LDH Test to Evaluate Sheet Metal Formability. Final Report of the LDH Committee of the North American Deep Drawing Research Group” 1988
- Hann P. private communication, Nov 1992
- Emmens W. C. “The Influence of Surface Roughness on Friction” Controlling sheet metal forming processes , 15 th Biennial Congress of the IDDRG, May 1988, Dearborn, ML ASM International 1988 63 70
- Fischer R. F. Schey J. A. “Tribological Factors Affecting the LDH Test” SAE Paper No 920432